HomeMy WebLinkAbout20241362.tiffUSDA United States
Department of
Agriculture
N
ACS
Natural
Resources
Conservation
Service
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Weld County,
Colorado,
Southern Part
February 6, 2024
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nres.usda.gov/wps/portal/nres/detail/soils/contactus/?
cid=nrcs142p2_053951).
142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface 2
How Soil Surveys Are Made 5
Soil Map 8
Soil Map 9
Legend 10
Map Unit Legend 11
Map Unit Descriptions 11
Weld County, Colorado, Southern Part 13
1 Altvan loam, 0 to 1 percent slopes 13
Soil Information for All Uses 15
Suitabilities and Limitations for Use 15
Building Site Development 15
Dwellings With Basements 15
References 21
Glossary 23
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil -vegetation -landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
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Custom Soil Resource Report
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil -landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil -landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field -observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
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Custom Soil Resource Report
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
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Soil Map► may not becalid at this scale.
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Map Scale: 1:1,220 if printed on A portrait (8.5" x 11") sheet.
529000
Meters
0 15 30 60 90
Feet
0 50 100
200 300
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
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MAP LEGEND
Area of Interest (AO!)
Area of Interest (AO1)
Soils
C
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
r,
O
0
v
•m 4
4
404
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
a
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
iair°§1 Aerial Photography
MAP INFORMATION
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA -MRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Weld County, Colorado, Southern Part
Survey Area Data: Version 22, Aug 24, 2023
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jun 8, 2021 Jun 12,
2021
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
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Custom Soil Resource Report
Map Unit Legend
Map
Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
1
Altvan
slopes
loam, 0 to 1
percent
5.7
100.0%
Totals for Area of Interest
5.7
100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
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Custom Soil Resource Report
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha -Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
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Custom Soil Resource Report
Weld County, Colorado, Southern Part
1—Altvan loam, 0 to 1 percent slopes
Map Unit Setting
National map unit symbol: 361j
Elevation: 4,500 to 4,900 feet
Mean annual precipitation: 14 to 16 inches
Mean annual air temperature: 46 to 48 degrees F
Frost -free period: 130 to 150 days
Farmland classification: Not prime farmland
Map Unit Composition
Altvan and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Altvan
Setting
Landform: Terraces
Down -slope shape: Linear
Across -slope shape: Linear
Parent material: Old alluvium
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 25 inches: clay loam
H3 - 25 to 60 inches: gravelly sand
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high
(0.20 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum content: 5 percent
Available water supply, 0 to 60 inches: Low (about 5.7 inches)
Interpretive groups
Land capability classification (irrigated): 3s
Land capability classification (non irrigated): 4e
Hydrologic Soil Group: B
Ecological site: R067BY002CO - Loamy Plains
Hydric soil rating: No
Minor Components
Cascajo
Percent of map unit: 9 percent
Hydric soil rating: No
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Custom Soil Resource Report
Aquic haplustolls
Percent of map unit: 1 percent
Landform: Swales
Hydric soil rating: Yes
Soil Information for All Uses
Suitabilities and Limitations for Use
The Suitabilities and Limitations for Use section includes various soil interpretations
displayed as thematic maps with a summary table for the soil map units in the
selected area of interest. A single value or rating for each map unit is generated by
aggregating the interpretive ratings of individual map unit components. This
aggregation process is defined for each interpretation.
Building Site Development
Building site development interpretations are designed to be used as tools for
evaluating soil suitability and identifying soil limitations for various construction
purposes. As part of the interpretation process, the rating applies to each soil in its
described condition and does not consider present land use. Example
interpretations can include corrosion of concrete and steel, shallow excavations,
dwellings with and without basements, small commercial buildings, local roads and
streets, and lawns and landscaping.
Dwellings With Basements
ENG - Engineering
Dwellings are single-family houses of three stories or less. For dwellings with
basements, the foundation is assumed to consist of spread footings of reinforced
concrete built on undisturbed soil at a depth of about 7 feet.
The ratings for dwellings are based on the soil properties that affect the capacity of
the soil to support a load without movement and on the properties that affect
excavation and construction costs. The properties that affect the load -supporting
capacity include depth to a water table, ponding, flooding, subsidence, linear
extensibility (shrink -swell potential), and compressibility. Compressibility is inferred
from the Unified classification of the soil. The properties that affect the ease and
amount of excavation include depth to a water table, ponding, flooding, slope, depth
to bedrock or a cemented pan, hardness of bedrock or a cemented pan, and the
amount and size of rock fragments.
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Custom Soil Resource Report
The ratings are both verbal and numerical. Rating class terms indicate the extent to
which the soils are limited by all of the soil features that affect the specified use.
"Not limited" indicates that the soil has features that are very favorable for the
specified use. Good performance and very low maintenance can be expected.
"Somewhat limited" indicates that the soil has features that are moderately
favorable for the specified use. The limitations can be overcome or minimized by
special planning, design, or installation. Fair performance and moderate
maintenance can be expected. "Very limited" indicates that the soil has one or more
features that are unfavorable for the specified use. The limitations generally cannot
be overcome without major soil reclamation, special design, or expensive
installation procedures. Poor performance and high maintenance can be expected.
Numerical ratings indicate the severity of individual limitations. The ratings are
shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations
between the point at which a soil feature has the greatest negative impact on the
use (1.00) and the point at which the soil feature is not a limitation (0.00).
The map unit components listed for each map unit in the accompanying Summary
by Map Unit table in Web Soil Survey or the Aggregation Report in Soil Data Viewer
are determined by the aggregation method chosen. An aggregated rating class is
shown for each map unit. The components listed for each map unit are only those
that have the same rating class as listed for the map unit. The percent composition
of each component in a particular map unit is presented to help the user better
understand the percentage of each map unit that has the rating presented.
Other components with different ratings may be present in each map unit. The
ratings for all components, regardless of the map unit aggregated rating, can be
viewed by generating the equivalent report from the Soil Reports tab in Web Soil
Survey or from the Soil Data Mart site. Onsite investigation may be needed to
validate these interpretations and to confirm the identity of the soil on a given site.
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Map Dwellings With Basements
528970
Soil Map► may not bevalid at this scale.
528910
528940
528970
529000
529030
529060
529090
Map Scale: 1:1,220 if printed on A portrait (8.5" x 11") sheet.
529000
Meters
0 15 30 60 90
Feet
0 50 100
200 300
529030
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
17
529060
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MAP LEGEND MAP INFORMATION
Area of Interest (AO!)
Area of Interest (A01)
Soils
Soil Rating Polygons
Very limited
Somewhat limited
Not limited
Not rated or not available
Soil Rating Lines
;t Very limited
Somewhat limited
Not limited
Not rated or not available
Soil Rating Points
Very limited
Somewhat limited
Not limited
Not rated or not available
O
O
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background The soil surveys that comprise your AOI were mapped at
ifrahticAerial Photography
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Weld County, Colorado, Southern Part
Survey Area Data: Version 22, Aug 24, 2023
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jun 8, 2021 Jun 12,
2021
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
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Custom Soil Resource Report
Tables Dwellings With Basements
Map unit
symbol
Map
unit name
Rating
Component
name (percent)
Rating reasons
(numeric
values)
Acres in AOI
Percent of AOI
1
Altvan
1
slopes
percent
loam, 0 to
Not limited
Altvan (90%)
5.7
100.0%
Totals for Area of Interest
5.7
100.0%
Rating
Acres in AOI
Percent of AOI
Not limited
5.7
100.0%
Totals for Area of Interest
5.7
100.0%
Rating Options Dwellings With Basements
Aggregation Method: Dominant Condition
Aggregation is the process by which a set of component attribute values is reduced
to a single value that represents the map unit as a whole.
A map unit is typically composed of one or more "components". A component is
either some type of soil or some nonsoil entity, e.g., rock outcrop. For the attribute
being aggregated, the first step of the aggregation process is to derive one attribute
value for each of a map unit's components. From this set of component attributes,
the next step of the aggregation process derives a single value that represents the
map unit as a whole. Once a single value for each map unit is derived, a thematic
map for soil map units can be rendered. Aggregation must be done because, on
any soil map, map units are delineated but components are not.
For each of a map unit's components, a corresponding percent composition is
recorded. A percent composition of 60 indicates that the corresponding component
typically makes up approximately 60% of the map unit. Percent composition is a
critical factor in some, but not all, aggregation methods.
The aggregation method "Dominant Condition" first groups like attribute values for
the components in a map unit. For each group, percent composition is set to the
sum of the percent composition of all components participating in that group. These
groups now represent "conditions" rather than components. The attribute value
associated with the group with the highest cumulative percent composition is
returned. If more than one group shares the highest cumulative percent
composition, the corresponding "tie -break" rule determines which value should be
returned. The "tie -break" rule indicates whether the lower or higher group value
should be returned in the case of a percent composition tie. The result returned by
this aggregation method represents the dominant condition throughout the map unit
only when no tie has occurred.
Component Percent Cutof• None Specified
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Custom Soil Resource Report
Components whose percent composition is below the cutoff value will not be
considered. If no cutoff value is specified, all components in the database will be
considered. The data for some contrasting soils of minor extent may not be in the
database, and therefore are not considered.
Tie -break Rule: Higher
The tie -break rule indicates which value should be selected from a set of multiple
candidate values, or which value should be selected in the event of a percent
composition tie.
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References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
N ational Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U .S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/
nres/detai I/national/soils/?cid=nres 142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nres. usda.gov/wps/portal/nres/detail/national/soils/?cid=n res142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=n res142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
U nited States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
U nited States Department of Agriculture, Natural Resources Conservation Service.
N ational forestry manual. http://www.nres.usda.gov/wps/portal/nres/detail/soils/
home/?cid=nrcs142p2_053374
p2_053374
U nited States Department of Agriculture, Natural Resources Conservation Service.
N ational range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepastu re/?cid=stelprdb 1043084
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U nited States Department of Agriculture, Natural Resources Conservation Service.
N ational soil survey handbook, title 430 -VI. http://www.nrcs.usda.gov/wps/portal/
nres/detai I/soils/scientists/?cid=nres 142p2 054242
U nited States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nres.usda.gov/wps/portal/nres/detail/national/soils/?
cid=nrcs142p2_053624
U nited States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nres.usda.gov/Internet/FSE_DOCUMENTS/nres142p2_052290.pdf
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Glossary
Many of the terms relating to landforms, geology, and geomorphology are defined in
more detail in the following National Soil Survey Handbook link: "National Soil
Survey Handbook."
ABC soil
A soil having an A, a B, and a C horizon.
Ablation till
Loose, relatively permeable earthy material deposited during the downwasting
of nearly static glacial ice, either contained within or accumulated on the surface
of the glacier.
AC soil
A soil having only an A and a C horizon. Commonly, such soil formed in recent
alluvium or on steep, rocky slopes.
Aeration, soil
The exchange of air in soil with air from the atmosphere. The air in a well
aerated soil is similar to that in the atmosphere; the air in a poorly aerated soil is
considerably higher in carbon dioxide and lower in oxygen.
Aggregate, soil
Many fine particles held in a single mass or cluster. Natural soil aggregates,
such as granules, blocks, or prisms, are called peds. Clods are aggregates
produced by tillage or logging.
Alkali (sodic) soil
A soil having so high a degree of alkalinity (pH 8.5 or higher) or so high a
percentage of exchangeable sodium (15 percent or more of the total
exchangeable bases), or both, that plant growth is restricted.
Alluvial cone
A semiconical type of alluvial fan having very steep slopes. It is higher,
narrower, and steeper than a fan and is composed of coarser and thicker layers
of material deposited by a combination of alluvial episodes and (to a much
lesser degree) landslides (debris flow). The coarsest materials tend to be
concentrated at the apex of the cone.
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Alluvial fan
A low, outspread mass of loose materials and/or rock material, commonly with
gentle slopes. It is shaped like an open fan or a segment of a cone. The
material was deposited by a stream at the place where it issues from a narrow
mountain valley or upland valley or where a tributary stream is near or at its
junction with the main stream. The fan is steepest near its apex, which points
upstream, and slopes gently and convexly outward (downstream) with a gradual
decrease in gradient.
Alluvium
Unconsolidated material, such as gravel, sand, silt, clay, and various mixtures of
these, deposited on land by running water.
Alpha,alpha-dipyridyl
pha-di pyridyl
A compound that when dissolved in ammonium acetate is used to detect the
presence of reduced iron (Fe II) in the soil. A positive reaction implies reducing
conditions and the likely presence of redoximorphic features.
Animal unit month (AUM)
The amount of forage required by one mature cow of approximately 1,000
pounds weight, with or without a calf, for 1 month.
Aquic conditions
Current soil wetness characterized by saturation, reduction, and redoximorphic
features.
Argillic horizon
A subsoil horizon characterized by an accumulation of illuvial clay.
Arroyo
The flat -floored channel of an ephemeral stream, commonly with very steep to
vertical banks cut in unconsolidated material. It is usually dry but can be
transformed into a temporary watercourse or short-lived torrent after heavy rain
within the watershed.
Aspect
The direction toward which a slope faces. Also called slope aspect.
Association, soil
A group of soils or miscellaneous areas geographically associated in a
characteristic repeating pattern and defined and delineated as a single map
unit.
Available water capacity (available moisture capacity)
The capacity of soils to hold water available for use by most plants. It is
commonly defined as the difference between the amount of soil water at field
moisture capacity and the amount at wilting point. It is commonly expressed as
inches of water per inch of soil. The capacity, in inches, in a 60 -inch profile or to
a limiting layer is expressed as:
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Very low: 0 to 3
Low: 3 to 6
Moderate: 6 to 9
High: 9 to 12
Very high: More than 12
Backslope
The position that forms the steepest and generally linear, middle portion of a
hillslope. In profile, backslopes are commonly bounded by a convex shoulder
above and a concave footslope below.
Backswamp
A flood -plain landform. Extensive, marshy or swampy, depressed areas of flood
plains between natural levees and valley sides or terraces.
Badland
A landscape that is intricately dissected and characterized by a very fine
drainage network with high drainage densities and short, steep slopes and
narrow interfluves. Badlands develop on surfaces that have little or no
vegetative cover overlying unconsolidated or poorly cemented materials (clays,
silts, or sandstones) with, in some cases, soluble minerals, such as gypsum or
halite.
Bajada
A broad, gently inclined alluvial piedmont slope extending from the base of a
mountain range out into a basin and formed by the lateral coalescence of a
series of alluvial fans. Typically, it has a broadly undulating transverse profile,
parallel to the mountain front, resulting from the convexities of component fans.
The term is generally restricted to constructional slopes of intermontane basins.
Basal area
The area of a cross section of a tree, generally referring to the section at breast
height and measured outside the bark. It is a measure of stand density,
commonly expressed in square feet.
Base saturation
The degree to which material having cation -exchange properties is saturated
with exchangeable bases (sum of Ca, Mg, Na, and K), expressed as a
percentage of the total cation -exchange capacity.
Base slope (geomorphology)
A geomorphic component of hills consisting of the concave to linear
(perpendicular to the contour) slope that, regardless of the lateral shape, forms
an apron or wedge at the bottom of a hillside dominated by colluvium and
slope -wash sediments (for example, slope alluvium).
Bedding plane
A planar or nearly planar bedding surface that visibly separates each
successive layer of stratified sediment or rock (of the same or different lithology)
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from the preceding or following layer; a plane of deposition. It commonly marks
a change in the circumstances of deposition and may show a parting, a color
difference, a change in particle size, or various combinations of these. The term
is commonly applied to any bedding surface, even one that is conspicuously
bent or deformed by folding.
Bedding system
A drainage system made by plowing, grading, or otherwise shaping the surface
of a flat field. It consists of a series of low ridges separated by shallow, parallel
dead furrows.
Bedrock
The solid rock that underlies the soil and other unconsolidated material or that
is exposed at the surface.
Bedrock -controlled topography
A landscape where the configuration and relief of the landforms are determined
or strongly influenced by the underlying bedrock.
Bench terrace
A raised, level or nearly level strip of earth constructed on or nearly on a
contour, supported by a barrier of rocks or similar material, and designed to
make the soil suitable for tillage and to prevent accelerated erosion.
Bisequum
Two sequences of soil horizons, each of which consists of an illuvial horizon
and the overlying eluvial horizons.
Blowout (map symbol)
A saucer-, cup-, or trough -shaped depression formed by wind erosion on a
preexisting dune or other sand deposit, especially in an area of shifting sand or
loose soil or where protective vegetation is disturbed or destroyed. The
adjoining accumulation of sand derived from the depression, where
recognizable, is commonly included. Blowouts are commonly small.
Borrow pit (map symbol)
An open excavation from which soil and underlying material have been
removed, usually for construction purposes.
Bottom land
An informal term loosely applied to various portions of a flood plain.
Boulders
Rock fragments larger than 2 feet (60 centimeters) in diameter.
Breaks
A landscape or tract of steep, rough or broken land dissected by ravines and
gullies and marking a sudden change in topography.
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Breast height
An average height of 4.5 feet above the ground surface; the point on a tree
where diameter measurements are ordinarily taken.
Brush management
Use of mechanical, chemical, or biological methods to make conditions
favorable for reseeding or to reduce or eliminate competition from woody
vegetation and thus allow understory grasses and forbs to recover. Brush
management increases forage production and thus reduces the hazard of
erosion. It can improve the habitat for some species of wildlife.
Butte
An isolated, generally flat-topped hill or mountain with relatively steep slopes
and talus or precipitous cliffs and characterized by summit width that is less
than the height of bounding escarpments; commonly topped by a caprock of
resistant material and representing an erosion remnant carved from flat -lying
rocks.
Cable yarding
A method of moving felled trees to a nearby central area for transport to a
processing facility. Most cable yarding systems involve use of a drum, a pole,
and wire cables in an arrangement similar to that of a rod and reel used for
fishing. To reduce friction and soil disturbance, felled trees generally are reeled
in while one end is lifted or the entire log is suspended.
Calcareous soil
A soil containing enough calcium carbonate (commonly combined with
magnesium carbonate) to effervesce visibly when treated with cold, dilute
hydrochloric acid.
Caliche
A general term for a prominent zone of secondary carbonate accumulation in
surficial materials in warm, subhumid to arid areas. Caliche is formed by both
geologic and pedologic processes. Finely crystalline calcium carbonate forms a
nearly continuous surface -coating and void -filling medium in geologic (parent)
materials. Cementation ranges from weak in nonindurated forms to very strong
in indurated forms. Other minerals (e.g., carbonates, silicate, and sulfate) may
occur as accessory cements. Most petrocalcic horizons and some calcic
horizons are caliche.
California bearing ratio (CBR)
The load -supporting capacity of a soil as compared to that of standard crushed
limestone, expressed as a ratio. First standardized in California. A soil having a
CBR of 16 supports 16 percent of the load that would be supported by standard
crushed limestone, per unit area, with the same degree of distortion.
Canopy
The leafy crown of trees or shrubs. (See Crown.)
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Canyon
A long, deep, narrow valley with high, precipitous walls in an area of high local
relief.
Capillary water
Water held as a film around soil particles and in tiny spaces between particles.
Surface tension is the adhesive force that holds capillary water in the soil.
Catena
A sequence, or "chain," of soils on a landscape that formed in similar kinds of
parent material and under similar climatic conditions but that have different
characteristics as a result of differences in relief and drainage.
Cation
An ion carrying a positive charge of electricity. The common soil cations are
calcium, potassium, magnesium, sodium, and hydrogen.
Cation -exchange capacity
The total amount of exchangeable cations that can be held by the soil,
expressed in terms of milliequivalents per 100 grams of soil at neutrality (pH
7.0) or at some other stated pH value. The term, as applied to soils, is
synonymous with base -exchange capacity but is more precise in meaning.
Catsteps
See Terracettes.
Cement rock
Shaly limestone used in the manufacture of cement.
Channery soil material
Soil material that has, by volume, 15 to 35 percent thin, flat fragments of
sandstone, shale, slate, limestone, or schist as much as 6 inches (15
centimeters) along the longest axis. A single piece is called a channer.
Chemical treatment
Control of unwanted vegetation through the use of chemicals.
Chiseling
Tillage with an implement having one or more soil -penetrating points that
shatter or loosen hard, compacted layers to a depth below normal plow depth.
Cirque
A steep -walled, semicircular or crescent -shaped, half -bowl -like recess or
hollow, commonly situated at the head of a glaciated mountain valley or high on
the side of a mountain. It was produced by the erosive activity of a mountain
glacier. It commonly contains a small round lake (tarn).
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Clay
As a soil separate, the mineral soil particles less than 0.002 millimeter in
diameter. As a soil textural class, soil material that is 40 percent or more clay,
less than 45 percent sand, and less than 40 percent silt.
Clay depletions
See Redoximorphic features.
Clay film
A thin coating of oriented clay on the surface of a soil aggregate or lining pores
or root channels. Synonyms: clay coating, clay skin.
Clay spot (map symbol)
A spot where the surface texture is silty clay or clay in areas where the surface
layer of the soils in the surrounding map unit is sandy loam, loam, silt loam, or
coarser.
Claypan
A dense, compact subsoil layer that contains much more clay than the overlying
materials, from which it is separated by a sharply defined boundary. The layer
restricts the downward movement of water through the soil. A claypan is
commonly hard when dry and plastic and sticky when wet.
Climax plant community
The stabilized plant community on a particular site. The plant cover reproduces
itself and does not change so long as the environment remains the same.
Coarse textured soil
Sand or loamy sand.
Cobble (or cobblestone)
A rounded or partly rounded fragment of rock 3 to 10 inches (7.6 to 25
centimeters) in diameter.
Cobbly soil material
Material that has 15 to 35 percent, by volume, rounded or partially rounded rock
fragments 3 to 10 inches (7.6 to 25 centimeters) in diameter. Very cobbly soil
material has 35 to 60 percent of these rock fragments, and extremely cobbly
soil material has more than 60 percent.
COLE (coefficient of linear extensibility)
See Linear extensibility.
Colluvium
Unconsolidated, unsorted earth material being transported or deposited on side
slopes and/or at the base of slopes by mass movement (e.g., direct
gravitational action) and by local, unconcentrated runoff.
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Complex slope
Irregular or variable slope. Planning or establishing terraces, diversions, and
other water -control structures on a complex slope is difficult.
Complex, soil
A map unit of two or more kinds of soil or miscellaneous areas in such an
intricate pattern or so small in area that it is not practical to map them
separately at the selected scale of mapping. The pattern and proportion of the
soils or miscellaneous areas are somewhat similar in all areas.
Concretions
See Redoximorphic features.
Conglomerate
A coarse grained, clastic sedimentary rock composed of rounded or subangular
rock fragments more than 2 millimeters in diameter. It commonly has a matrix of
sand and finer textured material. Conglomerate is the consolidated equivalent
of gravel.
Conservation cropping system
Growing crops in combination with needed cultural and management practices.
In a good conservation cropping system, the soil -improving crops and practices
more than offset the effects of the soil -depleting crops and practices. Cropping
systems are needed on all tilled soils. Soil -improving practices in a conservation
cropping system include the use of rotations that contain grasses and legumes
and the return of crop residue to the soil. Other practices include the use of
green manure crops of grasses and legumes, proper tillage, adequate
fertilization, and weed and pest control.
Conservation tillage
A tillage system that does not invert the soil and that leaves a protective amount
of crop residue on the surface throughout the year.
Consistence, soil
Refers to the degree of cohesion and adhesion of soil material and its
resistance to deformation when ruptured. Consistence includes resistance of
soil material to rupture and to penetration; plasticity, toughness, and stickiness
of puddled soil material; and the manner in which the soil material behaves
when subject to compression. Terms describing consistence are defined in the
"Soil Survey Manual."
Contour striperopping
Growing crops in strips that follow the contour. Strips of grass or close -growing
crops are alternated with strips of clean -tilled crops or summer fallow.
Control section
The part of the soil on which classification is based. The thickness varies
among different kinds of soil, but for many it is that part of the soil profile
between depths of 10 inches and 40 or 80 inches.
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Coprogenous earth (sedimentary peat)
A type of limnic layer composed predominantly of fecal material derived from
aquatic animals.
Corrosion (geomorphology)
A process of erosion whereby rocks and soil are removed or worn away by
natural chemical processes, especially by the solvent action of running water,
but also by other reactions, such as hydrolysis, hydration, carbonation, and
oxidation.
Corrosion (soil survey interpretations)
Soil -induced electrochemical or chemical action that dissolves or weakens
concrete or uncoated steel.
Cover crop
A close -growing crop grown primarily to improve and protect the soil between
periods of regular crop production, or a crop grown between trees and vines in
orchards and vineyards.
Crop residue management
Returning crop residue to the soil, which helps to maintain soil structure,
organic matter content, and fertility and helps to control erosion.
Cropping system
Growing crops according to a planned system of rotation and management
practices.
Cross -slope farming
Deliberately conducting farming operations on sloping farmland in such a way
that tillage is across the general slope.
Crown
The upper part of a tree or shrub, including the living branches and their foliage.
Cryoturbate
A mass of soil or other unconsolidated earthy material moved or disturbed by
frost action. It is typically coarser than the underlying material.
Cuesta
An asymmetric ridge capped by resistant rock layers of slight or moderate dip
(commonly less than 15 percent slopes); a type of homocline produced by
differential erosion of interbedded resistant and weak rocks. A cuesta has a
long, gentle slope on one side (dip slope) that roughly parallels the inclined
beds; on the other side, it has a relatively short and steep or clifflike slope
(scarp) that cuts through the tilted rocks.
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Culmination of the mean annual increment (CMAI)
The average annual increase per acre in the volume of a stand. Computed by
dividing the total volume of the stand by its age. As the stand increases in age,
the mean annual increment continues to increase until mortality begins to
reduce the rate of increase. The point where the stand reaches its maximum
annual rate of growth is called the culmination of the mean annual increment.
Cutbanks cave
The walls of excavations tend to cave in or slough.
Decreasers
The most heavily grazed climax range plants. Because they are the most
palatable, they are the first to be destroyed by overgrazing.
Deferred grazing
Postponing grazing or resting grazing land for a prescribed period.
Delta
A body of alluvium having a surface that is fan shaped and nearly flat;
deposited at or near the mouth of a river or stream where it enters a body of
relatively quiet water, generally a sea or lake.
Dense layer
A very firm, massive layer that has a bulk density of more than 1.8 grams per
cubic centimeter. Such a layer affects the ease of digging and can affect filling
and compacting.
Depression, closed (map symbol)
A shallow, saucer -shaped area that is slightly lower on the landscape than the
surrounding area and that does not have a natural outlet for surface drainage.
Depth, soil
Generally, the thickness of the soil over bedrock. Very deep soils are more than
60 inches deep over bedrock; deep soils, 40 to 60 inches; moderately deep, 20
to 40 inches; shallow, 10 to 20 inches; and very shallow, less than 10 inches.
Desert pavement
A natural, residual concentration or layer of wind -polished, closely packed
gravel, boulders, and other rock fragments mantling a desert surface. It forms
where wind action and sheetwash have removed all smaller particles or where
rock fragments have migrated upward through sediments to the surface. It
typically protects the finer grained underlying material from further erosion.
Diatomaceous earth
A geologic deposit of fine, grayish siliceous material composed chiefly or
entirely of the remains of diatoms.
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Dip slope
A slope of the land surface, roughly determined by and approximately
conforming to the dip of the underlying bedrock.
Diversion (or diversion terrace)
A ridge of earth, generally a terrace, built to protect downslope areas by
diverting runoff from its natural course.
Divided -slope farming
A form of field striperopping in which crops are grown in a systematic
arrangement of two strips, or bands, across the slope to reduce the hazard of
water erosion. One strip is in a close -growing crop that provides protection from
erosion, and the other strip is in a crop that provides less protection from
erosion. This practice is used where slopes are not long enough to permit a full
striperopping pattern to be used.
Drainage class (natural)
Refers to the frequency and duration of wet periods under conditions similar to
those under which the soil formed. Alterations of the water regime by human
activities, either through drainage or irrigation, are not a consideration unless
they have significantly changed the morphology of the soil. Seven classes of
natural soil drainage are recognized excessively drained, somewhat
excessively drained, well drained, moderately well drained, somewhat poorly
drained, poorly drained, and very poorly drained. These classes are defined in
the "Soil Survey Manual."
Drainage, surface
Runoff, or surface flow of water, from an area.
Drainageway
A general term for a course or channel along which water moves in draining an
area. A term restricted to relatively small, linear depressions that at some time
move concentrated water and either do not have a defined channel or have only
a small defined channel.
Draw
A small stream valley that generally is shallower and more open than a ravine
or gulch and that has a broader bottom. The present stream channel may
appear inadequate to have cut the drainageway that it occupies.
Drift
A general term applied to all mineral material (clay, silt, sand, gravel, and
boulders) transported by a glacier and deposited directly by or from the ice or
transported by running water emanating from a glacier. Drift includes
unstratified material (till) that forms moraines and stratified deposits that form
outwash plains, eskers, kames, varves, and glaciofluvial sediments. The term is
generally applied to Pleistocene glacial deposits in areas that no longer contain
glaciers.
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Drumlin
A low, smooth, elongated oval hill, mound, or ridge of compact till that has a
core of bedrock or drift. It commonly has a blunt nose facing the direction from
which the ice approached and a gentler slope tapering in the other direction.
The longer axis is parallel to the general direction of glacier flow. Drumlins are
products of streamline (laminar) flow of glaciers, which molded the subglacial
floor through a combination of erosion and deposition.
Duff
A generally firm organic layer on the surface of mineral soils. It consists of fallen
plant material that is in the process of decomposition and includes everything
from the litter on the surface to underlying pure humus.
Dune
A low mound, ridge, bank, or hill of loose, windblown granular material
(generally sand), either barren and capable of movement from place to place or
covered and stabilized with vegetation but retaining its characteristic shape.
Earthy fill
See Mine spoil.
Ecological site
An area where climate, soil, and relief are sufficiently uniform to produce a
distinct natural plant community. An ecological site is the product of all the
environmental factors responsible for its development. It is typified by an
association of species that differ from those on other ecological sites in kind
and/or proportion of species or in total production.
Eluviation
The movement of material in true solution or colloidal suspension from one
place to another within the soil. Soil horizons that have lost material through
eluviation are eluvial; those that have received material are illuvial.
Endosaturation
A type of saturation of the soil in which all horizons between the upper
boundary of saturation and a depth of 2 meters are saturated.
Eolian deposit
Sand-, silt-, or clay -sized clastic material transported and deposited primarily by
wind, commonly in the form of a dune or a sheet of sand or loess.
Ephemeral stream
A stream, or reach of a stream, that flows only in direct response to
precipitation. It receives no long -continued supply from melting snow or other
source, and its channel is above the water table at all times.
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Episaturation
A type of saturation indicating a perched water table in a soil in which saturated
layers are underlain by one or more unsaturated layers within 2 meters of the
surface.
Erosion
The wearing away of the land surface by water, wind, ice, or other geologic
agents and by such processes as gravitational creep.
Erosion (accelerated)
Erosion much more rapid than geologic erosion, mainly as a result of human or
animal activities or of a catastrophe in nature, such as a fire, that exposes the
surface.
Erosion (geologic)
Erosion caused by geologic processes acting over long geologic periods and
resulting in the wearing away of mountains and the building up of such
landscape features as flood plains and coastal plains. Synonym: natural
erosion.
Erosion pavement
A surficial lag concentration or layer of gravel and other rock fragments that
remains on the soil surface after sheet or rill erosion or wind has removed the
finer soil particles and that tends to protect the underlying soil from further
erosion.
Erosion surface
A land surface shaped by the action of erosion, especially by running water.
Escarpment
A relatively continuous and steep slope or cliff breaking the general continuity of
more gently sloping land surfaces and resulting from erosion or faulting. Most
commonly applied to cliffs produced by differential erosion. Synonym: scarp.
Escarpment, bedrock (map symbol)
A relatively continuous and steep slope or cliff, produced by erosion or faulting,
that breaks the general continuity of more gently sloping land surfaces.
Exposed material is hard or soft bedrock.
Escarpment, nonbedrock (map symbol)
A relatively continuous and steep slope or cliff, generally produced by erosion
but in some places produced by faulting, that breaks the continuity of more
gently sloping land surfaces. Exposed earthy material is nonsoil or very shallow
soil.
Esker
A long, narrow, sinuous, steep -sided ridge of stratified sand and gravel
deposited as the bed of a stream flowing in an ice tunnel within or below the ice
(subglacial) or between ice walls on top of the ice of a wasting glacier and left
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behind as high ground when the ice melted. Eskers range in length from less
than a kilometer to more than 160 kilometers and in height from 3 to 30 meters.
Extrusive rock
Igneous rock derived from deep-seated molten matter (magma) deposited and
cooled on the earth's surface.
Fallow
Cropland left idle in order to restore productivity through accumulation of
moisture. Summer fallow is common in regions of limited rainfall where cereal
grain is grown. The soil is tilled for at least one growing season for weed control
and decomposition of plant residue.
Fan remnant
A general term for landforms that are the remaining parts of older fan
landforms, such as alluvial fans, that have been either dissected or partially
buried.
Fertility, soil
The quality that enables a soil to provide plant nutrients, in adequate amounts
and in proper balance, for the growth of specified plants when light, moisture,
temperature, tilth, and other growth factors are favorable.
Fibric soil material (peat)
The least decomposed of all organic soil material. Peat contains a large amount
of well preserved fiber that is readily identifiable according to botanical origin.
Peat has the lowest bulk density and the highest water content at saturation of
all organic soil material.
Field moisture capacity
The moisture content of a soil, expressed as a percentage of the ovendry
weight, after the gravitational, or free, water has drained away; the field
moisture content 2 or 3 days after a soaking rain; also called normal field
capacity, normal moisture capacity, or capillary capacity.
Fill slope
A sloping surface consisting of excavated soil material from a road cut. It
commonly is on the downhill side of the road.
Fine textured soil
Sandy clay, silty clay, or clay.
Firebreak
An area cleared of flammable material to stop or help control creeping or
running fires. It also serves as a line from which to work and to facilitate the
movement of firefighters and equipment. Designated roads also serve as
firebreaks.
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First bottom
An obsolete, informal term loosely applied to the lowest flood -plain steps that
are subject to regular flooding.
Flaggy soil material
Material that has, by volume, 15 to 35 percent flagstones. Very flaggy soil
material has 35 to 60 percent flagstones, and extremely flaggy soil material has
more than 60 percent flagstones.
Flagstone
A thin fragment of sandstone, limestone, slate, shale, or (rarely) schist 6 to 15
inches (15 to 38 centimeters) long.
Flood plain
The nearly level plain that borders a stream and is subject to flooding unless
protected artificially.
Flood -plain landforms
A variety of constructional and erosional features produced by stream channel
migration and flooding. Examples include backswamps, flood -plain splays,
meanders, meander belts, meander scrolls, oxbow lakes, and natural levees.
Flood -plain splay
A fan -shaped deposit or other outspread deposit formed where an overloaded
stream breaks through a levee (natural or artificial) and deposits its material
(commonly coarse grained) on the flood plain.
Flood -plain step
An essentially flat, terrace -like alluvial surface within a valley that is frequently
covered by floodwater from the present stream; any approximately horizontal
surface still actively modified by fluvial scour and/or deposition. May occur
individually or as a series of steps.
Fluvial
Of or pertaining to rivers or streams; produced by stream or river action.
Foothills
A region of steeply sloping hills that fringes a mountain range or high -plateau
escarpment. The hills have relief of as much as 1,000 feet (300 meters).
Footslope
The concave surface at the base of a hillslope. A footslope is a transition zone
between upslope sites of erosion and transport (shoulders and backslopes) and
downslope sites of deposition (toeslopes).
Forb
Any herbaceous plant not a grass or a sedge.
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Forest cover
All trees and other woody plants (underbrush) covering the ground in a forest.
Forest type
A stand of trees similar in composition and development because of given
physical and biological factors by which it may be differentiated from other
stands.
Fragipan
A loamy, brittle subsurface horizon low in porosity and content of organic matter
and low or moderate in clay but high in silt or very fine sand. A fragipan appears
cemented and restricts roots. When dry, it is hard or very hard and has a higher
bulk density than the horizon or horizons above. When moist, it tends to rupture
suddenly under pressure rather than to deform slowly.
Genesis, soil
The mode of origin of the soil. Refers especially to the processes or soil -forming
factors responsible for the formation of the solum, or true soil, from the
unconsolidated parent material.
Gilgai
Commonly, a succession of microbasins and microknolls in nearly level areas or
of microvalleys and microridges parallel with the slope. Typically, the microrelief
of clayey soils that shrink and swell considerably with changes in moisture
content.
Glaciofluvial deposits
Material moved by glaciers and subsequently sorted and deposited by streams
flowing from the melting ice. The deposits are stratified and occur in the form of
outwash plains, valley trains, deltas, kames, eskers, and kame terraces.
Glaciolacustrine deposits
Material ranging from fine clay to sand derived from glaciers and deposited in
glacial lakes mainly by glacial meltwater. Many deposits are bedded or
laminated.
Gleyed soil
Soil that formed under poor drainage, resulting in the reduction of iron and other
elements in the profile and in gray colors.
Graded striperopping
Growing crops in strips that grade toward a protected waterway.
Grassed waterway
A natural or constructed waterway, typically broad and shallow, seeded to grass
as protection against erosion. Conducts surface water away from cropland.
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Gravel
Rounded or angular fragments of rock as much as 3 inches (2 millimeters to 7.6
centimeters) in diameter. An individual piece is a pebble.
Gravel pit (map symbol)
An open excavation from which soil and underlying material have been
removed and used, without crushing, as a source of sand or gravel.
Gravelly soil material
Material that has 15 to 35 percent, by volume, rounded or angular rock
fragments, not prominently flattened, as much as 3 inches (7.6 centimeters) in
diameter.
Gravelly spot (map symbol)
A spot where the surface layer has more than 35 percent, by volume, rock
fragments that are mostly less than 3 inches in diameter in an area that has
less than 15 percent rock fragments.
Green manure crop (agronomy)
A soil -improving crop grown to be plowed under in an early stage of maturity or
soon after maturity.
Ground water
Water filling all the unblocked pores of the material below the water table.
Gully (map symbol)
A small, steep -sided channel caused by erosion and cut in unconsolidated
materials by concentrated but intermittent flow of water. The distinction between
a gully and a rill is one of depth. A gully generally is an obstacle to farm
machinery and is too deep to be obliterated by ordinary tillage whereas a rill is
of lesser depth and can be smoothed over by ordinary tillage.
Hard bedrock
Bedrock that cannot be excavated except by blasting or by the use of special
equipment that is not commonly used in construction.
Hard to reclaim
Reclamation is difficult after the removal of soil for construction and other uses.
Revegetation and erosion control are extremely difficult.
Hardpan
A hardened or cemented soil horizon, or layer. The soil material is sandy, loamy,
or clayey and is cemented by iron oxide, silica, calcium carbonate, or other
substance.
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Head slope (geomorphology)
A geomorphic component of hills consisting of a laterally concave area of a
hillside, especially at the head of a drainageway. The overland waterflow is
converging.
Hemic soil material (mucky peat)
Organic soil material intermediate in degree of decomposition between the less
decomposed fibric material and the more decomposed sapric material.
High -residue crops
Such crops as small grain and corn used for grain. If properly managed, residue
from these crops can be used to control erosion until the next crop in the
rotation is established. These crops return large amounts of organic matter to
the soil.
Hill
A generic term for an elevated area of the land surface, rising as much as 1,000
feet above surrounding lowlands, commonly of limited summit area and having
a well defined outline. Slopes are generally more than 15 percent. The
distinction between a hill and a mountain is arbitrary and may depend on local
usage.
Hillslope
A generic term for the steeper part of a hill between its summit and the drainage
line, valley flat, or depression floor at the base of a hill.
Horizon, soil
A layer of soil, approximately parallel to the surface, having distinct
characteristics produced by soil -forming processes. In the identification of soil
horizons, an uppercase letter represents the major horizons. Numbers or
lowercase letters that follow represent subdivisions of the major horizons. An
explanation of the subdivisions is given in the "Soil Survey Manual." The major
horizons of mineral soil are as follows:
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O horizon: An organic layer of fresh and decaying plant residue.
L horizon: A layer of organic and mineral limnic materials, including
coprogenous earth (sedimentary peat), diatomaceous earth, and marl.
A horizon: The mineral horizon at or near the surface in which an accumulation
of humified organic matter is mixed with the mineral material. Also, a plowed
surface horizon, most of which was originally part of a B horizon.
E horizon: The mineral horizon in which the main feature is loss of silicate clay,
iron, aluminum, or some combination of these.
B horizon: The mineral horizon below an A horizon. The B horizon is in part a
layer of transition from the overlying A to the underlying C horizon. The B
horizon also has distinctive characteristics, such as (1) accumulation of clay,
sesquioxides, humus, or a combination of these; (2) prismatic or blocky
structure; (3) redder or browner colors than those in the A horizon; or (4) a
combination of these.
C horizon: The mineral horizon or layer, excluding indurated bedrock, that is
little affected by soil -forming processes and does not have the properties typical
of the overlying soil material. The material of a C horizon may be either like or
unlike that in which the solum formed. If the material is known to differ from that
in the solum, an Arabic numeral, commonly a 2, precedes the letter C.
Cr horizon: Soft, consolidated bedrock beneath the soil.
R layer Consolidated bedrock beneath the soil. The bedrock commonly
underlies a C horizon, but it can be directly below an A or a B horizon.
M layer A root -limiting subsoil layer consisting of nearly continuous, horizontally
oriented, human -manufactured materials.
W layer: A layer of water within or beneath the soil.
Humus
The well decomposed, more or less stable part of the organic matter in mineral
soils.
Hydrologic soil groups
Refers to soils grouped according to their runoff potential. The soil properties
that influence this potential are those that affect the minimum rate of water
infiltration on a bare soil during periods after prolonged wetting when the soil is
not frozen. These properties include depth to a seasonal high water table, the
infiltration rate, and depth to a layer that significantly restricts the downward
movement of water. The slope and the kind of plant cover are not considered
but are separate factors in predicting runoff.
Igneous rock
Rock that was formed by cooling and solidification of magma and that has not
been changed appreciably by weathering since its formation. Major varieties
include plutonic and volcanic rock (e.g., andesite, basalt, and granite).
Illuviation
The movement of soil material from one horizon to another in the soil profile.
Generally, material is removed from an upper horizon and deposited in a lower
horizon.
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Impervious soil
A soil through which water, air, or roots penetrate slowly or not at all. No soil is
absolutely impervious to air and water all the time.
Increasers
Species in the climax vegetation that increase in amount as the more desirable
plants are reduced by close grazing. Increasers commonly are the shorter
plants and the less palatable to livestock.
Infiltration
The downward entry of water into the immediate surface of soil or other
material, as contrasted with percolation, which is movement of water through
soil layers or material.
Infiltration capacity
The maximum rate at which water can infiltrate into a soil under a given set of
conditions.
Infiltration rate
The rate at which water penetrates the surface of the soil at any given instant,
usually expressed in inches per hour. The rate can be limited by the infiltration
capacity of the soil or the rate at which water is applied at the surface.
Intake rate
The average rate of water entering the soil under irrigation. Most soils have a
fast initial rate; the rate decreases with application time. Therefore, intake rate
for design purposes is not a constant but is a variable depending on the net
irrigation application. The rate of water intake, in inches per hour, is expressed
as follows:
Very low: Less than 0.2
Low: 0.2 to 0.4
Moderately low: 0.4 to 0.75
Moderate: 0.75 to 1.25
Moderately high: 1.25 to 1.75
High: 1.75 to 2.5
Very high: More than 2.5
Interfluve
A landform composed of the relatively undissected upland or ridge between two
adjacent valleys containing streams flowing in the same general direction. An
elevated area between two drainageways that sheds water to those
drainageways.
Interfluve (geomorphology)
A geomorphic component of hills consisting of the uppermost, comparatively
level or gently sloping area of a hill; shoulders of backwearing hillslopes can
narrow the upland or can merge, resulting in a strongly convex shape.
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Intermittent stream
A stream, or reach of a stream, that does not flow year-round but that is
commonly dry for 3 or more months out of 12 and whose channel is generally
below the local water table. It flows only during wet periods or when it receives
ground -water discharge or long, continued contributions from melting snow or
other surface and shallow subsurface sources.
Invaders
On range, plants that encroach into an area and grow after the climax
vegetation has been reduced by grazing. Generally, plants invade following
disturbance of the surface.
Iron depletions
See Redoximorphic features.
Irrigation
Application of water to soils to assist in production of crops. Methods of
irrigation are:
Basin: Water is applied rapidly to nearly level plains surrounded by levees or
dikes
Border: Water is applied at the upper end of a strip in which the lateral flow of
water is controlled by small earth ridges called border dikes, or borders.
Controlled flooding: Water is released at intervals from closely spaced field
ditches and distributed uniformly over the field.
Corrugation: Water is applied to small, closely spaced furrows or ditches in
fields of close -growing crops or in orchards so that it flows in only one direction.
Drip (or trickle): Water is applied slowly and under low pressure to the surface
of the soil or into the soil through such applicators as emitters, porous tubing, or
perforated pipe.
Furrow: Water is applied in small ditches made by cultivation implements.
Furrows are used for tree and row crops.
Sprinkler: Water is sprayed over the soil surface through pipes or nozzles from
a pressure system.
Subirrigation: Water is applied in open ditches or tile lines until the water table is
raised enough to wet the soil.
Wild flooding: Water, released at high points, is allowed to flow onto an area
without controlled distribution.
Kame
A low mound, knob, hummock, or short irregular ridge composed of stratified
sand and gravel deposited by a subglacial stream as a fan or delta at the
margin of a melting glacier; by a supraglacial stream in a low place or hole on
the surface of the glacier; or as a ponded deposit on the surface or at the
margin of stagnant ice.
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Karst (topography)
A kind of topography that formed in limestone, gypsum, or other soluble rocks
by dissolution and that is characterized by closed depressions, sinkholes,
caves, and underground drainage.
Knoll
A small, low, rounded hill rising above adjacent landforms.
Ksat
See Saturated hydraulic conductivity.
Lacustrine deposit
Material deposited in lake water and exposed when the water level is lowered
or the elevation of the land is raised.
Lake plain
A nearly level surface marking the floor of an extinct lake filled by well sorted,
generally fine textured, stratified deposits, commonly containing varves.
Lake terrace
A narrow shelf, partly cut and partly built, produced along a lakeshore in front of
a scarp line of low cliffs and later exposed when the water level falls.
Landfill (map symbol)
An area of accumulated waste products of human habitation, either above or
below natural ground level.
Landslide
A general, encompassing term for most types of mass movement landforms
and processes involving the downslope transport and outward deposition of soil
and rock materials caused by gravitational forces; the movement may or may
not involve saturated materials. The speed and distance of movement, as well
as the amount of soil and rock material, vary greatly.
Large stones
Rock fragments 3 inches (7.6 centimeters) or more across. Large stones
adversely affect the specified use of the soil.
Lava flow (map symbol)
A solidified, commonly lobate body of rock formed through lateral, surface
outpouring of molten lava from a vent or fissure.
Leaching
The removal of soluble material from soil or other material by percolating water.
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Levee (map symbol)
An embankment that confines or controls water, especially one built along the
banks of a river to prevent overflow onto lowlands.
Linear extensibility
Refers to the change in length of an unconfined clod as moisture content is
decreased from a moist to a dry state. Linear extensibility is used to determine
the shrink -swell potential of soils. It is an expression of the volume change
between the water content of the clod at 1/3- or 1/10 -bar tension (33kPa or
10kPa tension) and oven dryness. Volume change is influenced by the amount
and type of clay minerals in the soil. The volume change is the percent change
for the whole soil. If it is expressed as a fraction, the resulting value is COLE,
coefficient of linear extensibility.
Liquid limit
The moisture content at which the soil passes from a plastic to a liquid state.
Loam
Soil material that is 7 to 27 percent clay particles, 28 to 50 percent silt particles,
and less than 52 percent sand particles.
Loess
Material transported and deposited by wind and consisting dominantly of silt -
sized particles.
Low strength
The soil is not strong enough to support loads.
Low -residue crops
Such crops as corn used for silage, peas, beans, and potatoes. Residue from
these crops is not adequate to control erosion until the next crop in the rotation
is established. These crops return little organic matter to the soil.
Marl
An earthy, unconsolidated deposit consisting chiefly of calcium carbonate mixed
with clay in approximately equal proportions; formed primarily under freshwater
lacustrine conditions but also formed in more saline environments.
Marsh or swamp (map symbol)
A water -saturated, very poorly drained area that is intermittently or permanently
covered by water. Sedges, cattails, and rushes are the dominant vegetation in
marshes, and trees or shrubs are the dominant vegetation in swamps. Not used
in map units where the named soils are poorly drained or very poorly drained.
Mass movement
A generic term for the dislodgment and downslope transport of soil and rock
material as a unit under direct gravitational stress.
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Masses
See Redoximorphic features.
Meander belt
The zone within which migration of a meandering channel occurs; the flood -
plain area included between two imaginary lines drawn tangential to the outer
bends of active channel loops.
Meander scar
A crescent -shaped, concave or linear mark on the face of a bluff or valley wall,
produced by the lateral erosion of a meandering stream that impinged upon and
undercut the bluff.
Meander scroll
One of a series of long, parallel, close -fitting, crescent -shaped ridges and
troughs formed along the inner bank of a stream meander as the channel
migrated laterally down -valley and toward the outer bank.
Mechanical treatment
Use of mechanical equipment for seeding, brush management, and other
management practices.
Medium textured soil
Very fine sandy loam, loam, silt loam, or silt.
Mesa
A broad, nearly flat topped and commonly isolated landmass bounded by steep
slopes or precipitous cliffs and capped by layers of resistant, nearly horizontal
rocky material. The summit width is characteristically greater than the height of
the bounding escarpments.
Metamorphic rock
Rock of any origin altered in mineralogical composition, chemical composition,
or structure by heat, pressure, and movement at depth in the earth's crust.
Nearly all such rocks are crystalline.
Mine or quarry (map symbol)
An open excavation from which soil and underlying material have been
removed and in which bedrock is exposed. Also denotes surface openings to
underground mines.
Mine spoil
An accumulation of displaced earthy material, rock, or other waste material
removed during mining or excavation. Also called earthy fill.
Mineral soil
Soil that is mainly mineral material and low in organic material. Its bulk density
is more than that of organic soil.
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Minimum tillage
Only the tillage essential to crop production and prevention of soil damage.
Miscellaneous area
A kind of map unit that has little or no natural soil and supports little or no
vegetation.
Miscellaneous water (map symbol)
Small, constructed bodies of water that are used for industrial, sanitary, or
mining applications and that contain water most of the year.
Moderately coarse textured soil
Coarse sandy loam, sandy loam, or fine sandy loam.
Moderately fine textured soil
Clay loam, sandy clay loam, or silty clay loam.
Mollic epipedon
A thick, dark, humus -rich surface horizon (or horizons) that has high base
saturation and pedogenic soil structure. It may include the upper part of the
subsoil.
Moraine
In terms of glacial geology, a mound, ridge, or other topographically distinct
accumulation of unsorted, unstratified drift, predominantly till, deposited
primarily by the direct action of glacial ice in a variety of landforms. Also, a
general term for a landform composed mainly of till (except for kame moraines,
which are composed mainly of stratified outwash) that has been deposited by a
glacier. Some types of moraines are disintegration, end, ground, kame, lateral,
recessional, and terminal.
Morphology, soil
The physical makeup of the soil, including the texture, structure, porosity,
consistence, color, and other physical, mineral, and biological properties of the
various horizons, and the thickness and arrangement of those horizons in the
soil profile.
Mottling, soil
Irregular spots of different colors that vary in number and size. Descriptive
terms are as follows: abundance few, common, and many; size fine,
medium, and coarse; and contrast faint, distinct, and prominent. The size
measurements are of the diameter along the greatest dimension. Fine indicates
less than 5 millimeters (about 0.2 inch); medium, from 5 to 15 millimeters (about
0.2 to 0.6 inch); and coarse, more than 15 millimeters (about 0.6 inch).
Mountain
A generic term for an elevated area of the land surface, rising more than 1,000
feet (300 meters) above surrounding lowlands, commonly of restricted summit
area (relative to a plateau) and generally having steep sides. A mountain can
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occur as a single, isolated mass or in a group forming a chain or range.
Mountains are formed primarily by tectonic activity and/or volcanic action but
can also be formed by differential erosion.
Muck
Dark, finely divided, well decomposed organic soil material. (See Sapric soil
material.)
Mucky peat
See Hemic soil material.
Mudstone
A blocky or massive, fine grained sedimentary rock in which the proportions of
clay and silt are approximately equal. Also, a general term for such material as
clay, silt, claystone, siltstone, shale, and argillite and that should be used only
when the amounts of clay and silt are not known or cannot be precisely
identified.
Munsell notation
A designation of color by degrees of three simple variables hue, value, and
chroma. For example, a notation of 10YR 6/4 is a color with hue of 10YR, value
of 6, and chroma of 4.
N atric horizon
A special kind of argillic horizon that contains enough exchangeable sodium to
have an adverse effect on the physical condition of the subsoil.
Neutral soil
A soil having a pH value of 6.6 to 7.3. (See Reaction, soil.)
N odules
See Redoximorphic features.
N ose slope (geomorphology)
A geomorphic component of hills consisting of the projecting end (laterally
convex area) of a hillside. The overland waterflow is predominantly divergent.
Nose slopes consist dominantly of colluvium and slope -wash sediments (for
example, slope alluvium).
N utrient, plant
Any element taken in by a plant essential to its growth. Plant nutrients are
mainly nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron,
manganese, copper, boron, and zinc obtained from the soil and carbon,
hydrogen, and oxygen obtained from the air and water.
Organic matter
Plant and animal residue in the soil in various stages of decomposition. The
content of organic matter in the surface layer is described as follows:
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Very low: Less than 0.5 percent
Low: 0.5 to 1.0 percent
Moderately low: 1.0 to 2.0 percent
Moderate: 2.0 to 4.0 percent
High: 4.0 to 8.0 percent
Very high: More than 8.0 percent
Outwash
Stratified and sorted sediments (chiefly sand and gravel) removed or "washed
out" from a glacier by meltwater streams and deposited in front of or beyond the
end moraine or the margin of a glacier. The coarser material is deposited nearer
to the ice.
Outwash plain
An extensive lowland area of coarse textured glaciofluvial material. An outwash
plain is commonly smooth; where pitted, it generally is low in relief.
Paleoterrace
An erosional remnant of a terrace that retains the surface form and alluvial
deposits of its origin but was not emplaced by, and commonly does not grade
to, a present-day stream or drainage network.
Pan
A compact, dense layer in a soil that impedes the movement of water and the
growth of roots. For example, hardpan, fragipan, claypan, plowpan, and traffic
pan.
Parent material
The unconsolidated organic and mineral material in which soil forms.
Peat
Unconsolidated material, largely undecomposed organic matter, that has
accumulated under excess moisture. (See Fibric soil material.)
Ped
An individual natural soil aggregate, such as a granule, a prism, or a block.
Pedisediment
A layer of sediment, eroded from the shoulder and backslope of an erosional
slope, that lies on and is being (or was) transported across a gently sloping
erosional surface at the foot of a receding hill or mountain slope.
Pedon
The smallest volume that can be called "a soil." A pedon is three dimensional
and large enough to permit study of all horizons. Its area ranges from about 10
to 100 square feet (1 square meter to 10 square meters), depending on the
variability of the soil.
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Percolation
The movement of water through the soil.
Perennial water (map symbol)
Small, natural or constructed lakes, ponds, or pits that contain water most of the
year.
Permafrost
Ground, soil, or rock that remains at or below 0 degrees C for at least 2 years. It
is defined on the basis of temperature and is not necessarily frozen.
pH value
A numerical designation of acidity and alkalinity in soil. (See Reaction, soil.)
P hase, soil
A subdivision of a soil series based on features that affect its use and
management, such as slope, stoniness, and flooding.
P iping
Formation of subsurface tunnels or pi pelf ke cavities by water moving through
the soil.
Pitting
Pits caused by melting around ice. They form on the soil after plant cover is
removed.
P lastic limit
The moisture content at which a soil changes from semisolid to plastic.
P lasticity index
The numerical difference between the liquid limit and the plastic limit; the range
of moisture content within which the soil remains plastic.
P lateau (geomorphology)
A comparatively flat area of great extent and elevation; specifically, an extensive
land region that is considerably elevated (more than 100 meters) above the
adjacent lower lying terrain, is commonly limited on at least one side by an
abrupt descent, and has a flat or nearly level surface. A comparatively large
part of a plateau surface is near summit level.
P laya
The generally dry and nearly level lake plain that occupies the lowest parts of
closed depressions, such as those on intermontane basin floors. Temporary
flooding occurs primarily in response to precipitation and runoff. Playa deposits
are fine grained and may or may not have a high water table and saline
conditions.
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Plinthite
The sesquioxide-rich, humus -poor, highly weathered mixture of clay with quartz
and other diluents. It commonly appears as red mottles, usually in platy,
polygonal, or reticulate patterns. Plinthite changes irreversibly to an ironstone
hardpan or to irregular aggregates on repeated wetting and drying, especially if
it is exposed also to heat from the sun. In a moist soil, plinthite can be cut with a
spade. It is a form of laterite.
P lowpan
A compacted layer formed in the soil directly below the plowed layer.
Ponding
Standing water on soils in closed depressions. Unless the soils are artificially
drained, the water can be removed only by percolation or evapotranspiration.
Poorly graded
Refers to a coarse grained soil or soil material consisting mainly of particles of
nearly the same size. Because there is little difference in size of the particles,
density can be increased only slightly by compaction.
Pore linings
See Redoximorphic features.
Potential native plant community
See Climax plant community.
Potential rooting depth (effective rooting depth)
Depth to which roots could penetrate if the content of moisture in the soil were
adequate. The soil has no properties restricting the penetration of roots to this
depth.
P rescribed burning
Deliberately burning an area for specific management purposes, under the
appropriate conditions of weather and soil moisture and at the proper time of
day.
P roductivity, soil
The capability of a soil for producing a specified plant or sequence of plants
under specific management.
P rofile, soil
A vertical section of the soil extending through all its horizons and into the
parent material.
P roper grazing use
Grazing at an intensity that maintains enough cover to protect the soil and
maintain or improve the quantity and quality of the desirable vegetation. This
practice increases the vigor and reproduction capacity of the key plants and
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promotes the accumulation of litter and mulch necessary to conserve soil and
water.
Rangeland
Land on which the potential natural vegetation is predominantly grasses,
grasslike plants, forbs, or shrubs suitable for grazing or browsing. It includes
natural grasslands, savannas, many wetlands, some deserts, tundras, and
areas that support certain forb and shrub communities.
Reaction, soil
A measure of acidity or alkalinity of a soil, expressed as pH values. A soil that
tests to pH 7.0 is described as precisely neutral in reaction because it is neither
acid nor alkaline. The degrees of acidity or alkalinity, expressed as pH values,
are:
Ultra acid: Less than 3.5
Extremely acid: 3.5 to 4.4
Very strongly acid: 4.5 to 5.0
Strongly acid: 5.1 to 5.5
Moderately acid: 5.6 to 6.0
Slightly acid: 6.1 to 6.5
Neutral: 6.6 to 7.3
Slightly alkaline: 7.4 to 7.8
Moderately alkaline: 7.9 to 8.4
Strongly alkaline: 8.5 to 9.0
Very strongly alkaline: 9.1 and higher
Red beds
Sedimentary strata that are mainly red and are made up largely of sandstone
and shale.
Redoximorphic concentrations
See Redoximorphic features.
Redoximorphic depletions
See Redoximorphic features.
Redoximorphic features
Redoximorphic features are associated with wetness and result from alternating
periods of reduction and oxidation of iron and manganese compounds in the
soil. Reduction occurs during saturation with water, and oxidation occurs when
the soil is not saturated. Characteristic color patterns are created by these
processes. The reduced iron and manganese ions may be removed from a soil
if vertical or lateral fluxes of water occur, in which case there is no iron or
manganese precipitation in that soil. Wherever the iron and manganese are
oxidized and precipitated, they form either soft masses or hard concretions or
nodules. Movement of iron and manganese as a result of redoximorphic
processes in a soil may result in redoximorphic features that are defined as
follows:
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1. Redoximorphic concentrations. These are zones of apparent
accumulation of iron -manganese oxides, including:
A. Nodules and concretions, which are cemented bodies that can be
removed from the soil intact. Concretions are distinguished from
nodules on the basis of internal organization. A concretion typically
has concentric layers that are visible to the naked eye. Nodules do not
have visible organized internal structure; and
B. Masses, which are noncemented concentrations of substances within
the soil matrix; and
C. Pore linings, i.e., zones of accumulation along pores that may be
either coatings on pore surfaces or impregnations from the matrix
adjacent to the pores.
2. Redoximorphic depletions. These are zones of low chroma (chromas less
than those in the matrix) where either iron -manganese oxides alone or both
iron -manganese oxides and clay have been stripped out, including:
A. Iron depletions, i.e., zones that contain low amounts of iron and
manganese oxides but have a clay content similar to that of the
adjacent matrix; and
B. Clay depletions, i.e., zones that contain low amounts of iron,
manganese, and clay (often referred to as silt coatings or skeletans).
3. Reduced matrix. This is a soil matrix that has low chroma in situ but
undergoes a change in hue or chroma within 30 minutes after the soil
material has been exposed to air.
Reduced matrix
See Redoximorphic features.
Regolith
All unconsolidated earth materials above the solid bedrock. It includes material
weathered in place from all kinds of bedrock and alluvial, glacial, eolian,
lacustrine, and pyroclastic deposits.
Relief
The relative difference in elevation between the upland summits and the
lowlands or valleys of a given region.
Residuum (residual soil material)
Unconsolidated, weathered or partly weathered mineral material that
accumulated as bedrock disintegrated in place.
Rill
A very small, steep -sided channel resulting from erosion and cut in
unconsolidated materials by concentrated but intermittent flow of water. A rill
generally is not an obstacle to wheeled vehicles and is shallow enough to be
smoothed over by ordinary tillage.
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Riser
The vertical or steep side slope (e.g., escarpment) of terraces, flood -plain steps,
or other stepped landforms; commonly a recurring part of a series of natural,
steplike landforms, such as successive stream terraces.
Road cut
A sloping surface produced by mechanical means during road construction. It is
commonly on the uphill side of the road.
Rock fragments
Rock or mineral fragments having a diameter of 2 millimeters or more; for
example, pebbles, cobbles, stones, and boulders.
Rock outcrop (map symbol)
An exposure of bedrock at the surface of the earth. Not used where the named
soils of the surrounding map unit are shallow over bedrock or where "Rock
outcrop" is a named component of the map unit.
Root zone
The part of the soil that can be penetrated by plant roots.
Runoff
The precipitation discharged into stream channels from an area. The water that
flows off the surface of the land without sinking into the soil is called surface
runoff. Water that enters the soil before reaching surface streams is called
ground -water runoff or seepage flow from ground water.
Saline soil
A soil containing soluble salts in an amount that impairs growth of plants. A
saline soil does not contain excess exchangeable sodium.
Saline spot (map symbol)
An area where the surface layer has an electrical conductivity of 8 mmhos/cm
more than the surface layer of the named soils in the surrounding map unit. The
surface layer of the surrounding soils has an electrical conductivity of 2
mmhos/cm or less.
Sand
As a soil separate, individual rock or mineral fragments from 0.05 millimeter to
2.0 millimeters in diameter. Most sand grains consist of quartz. As a soil textural
class, a soil that is 85 percent or more sand and not more than 10 percent clay.
Sandstone
Sedimentary rock containing dominantly sand -sized particles.
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Sandy spot (map symbol)
A spot where the surface layer is loamy fine sand or coarser in areas where the
surface layer of the named soils in the surrounding map unit is very fine sandy
loam or finer.
Sapric soil material (muck)
The most highly decomposed of all organic soil material. Muck has the least
amount of plant fiber, the highest bulk density, and the lowest water content at
saturation of all organic soil material.
Saturated hydraulic conductivity (Ksat)
The ease with which pores of a saturated soil transmit water. Formally, the
proportionality coefficient that expresses the relationship of the rate of water
movement to hydraulic gradient in Darcy's Law, a law that describes the rate of
water movement through porous media. Commonly abbreviated as "Ksat."
Terms describing saturated hydraulic conductivity are:
Very high: 100 or more micrometers per second (14.17 or more inches per
hour)
High: 10 to 100 micrometers per second (1.417 to 14.17 inches per hour)
Moderately high: 1 to 10 micrometers per second (0.1417 inch to 1.417 inches
per hour)
Moderately low: 0.1 to 1 micrometer per second (0.01417 to 0.1417 inch per
hour)
Low: 0.01 to 0.1 micrometer per second (0.001417 to 0.01417 inch per hour)
Very low: Less than 0.01 micrometer per second (less than 0.001417 inch per
hour).
To convert inches per hour to micrometers per second, multiply inches per hour
by 7.0572. To convert micrometers per second to inches per hour, multiply
micrometers per second by 0.1417.
Saturation
Wetness characterized by zero or positive pressure of the soil water. Under
conditions of saturation, the water will flow from the soil matrix into an unlined
auger hole.
Scarification
The act of abrading, scratching, loosening, crushing, or modifying the surface to
increase water absorption or to provide a more tillable soil.
Sedimentary rock
A consolidated deposit of clastic particles, chemical precipitates, or organic
remains accumulated at or near the surface of the earth under normal low
temperature and pressure conditions. Sedimentary rocks include consolidated
equivalents of alluvium, colluvium, drift, and eolian, lacustrine, and marine
deposits. Examples are sandstone, siltstone, mudstone, claystone, shale,
conglomerate, limestone, dolomite, and coal.
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Sequum
A sequence consisting of an illuvial horizon and the overlying eluvial horizon.
(See Eluviation.)
Series, soil
A group of soils that have profiles that are almost alike, except for differences in
texture of the surface layer. All the soils of a series have horizons that are
similar in composition, thickness, and arrangement.
Severely eroded spot (map symbol)
An area where, on the average, 75 percent or more of the original surface layer
has been lost because of accelerated erosion. Not used in map units in which
"severely eroded," "very severely eroded," or "gullied" is part of the map unit
name.
S hale
Sedimentary rock that formed by the hardening of a deposit of clay, silty clay, or
silty clay loam and that has a tendency to split into thin layers.
S heet erosion
The removal of a fairly uniform layer of soil material from the land surface by the
action of rainfall and surface runoff.
S hort, steep slope (map symbol)
A narrow area of soil having slopes that are at least two slope classes steeper
than the slope class of the surrounding map unit.
S houlder
The convex, erosional surface near the top of a hillslope. A shoulder is a
transition from summit to backslope.
S hrink -swell
The shrinking of soil when dry and the swelling when wet. Shrinking and
swelling can damage roads, dams, building foundations, and other structures. It
can also damage plant roots.
S hrub -coppice dune
A small, streamlined dune that forms around brush and clump vegetation.
S ide slope (geomorphology)
A geomorphic component of hills consisting of a laterally planar area of a
hillside. The overland waterflow is predominantly parallel. Side slopes are
dominantly colluvium and slope -wash sediments.
S ilica
A combination of silicon and oxygen. The mineral form is called quartz.
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S ilica-sesquioxide ratio
The ratio of the number of molecules of silica to the number of molecules of
alumina and iron oxide. The more highly weathered soils or their clay fractions
in warm -temperate, humid regions, and especially those in the tropics, generally
have a low ratio.
S ilt
As a soil separate, individual mineral particles that range in diameter from the
upper limit of clay (0.002 millimeter) to the lower limit of very fine sand (0.05
millimeter). As a soil textural class, soil that is 80 percent or more silt and less
than 12 percent clay.
S iltstone
An indurated silt having the texture and composition of shale but lacking its fine
lamination or fissility; a massive mudstone in which silt predominates over clay.
S imilar soils
Soils that share limits of diagnostic criteria, behave and perform in a similar
manner, and have similar conservation needs or management requirements for
the major land uses in the survey area.
S inkhole (map symbol)
A closed, circular or elliptical depression, commonly funnel shaped,
characterized by subsurface drainage and formed either by dissolution of the
surface of underlying bedrock (e.g., limestone, gypsum, or salt) or by collapse
of underlying caves within bedrock. Complexes of sinkholes in carbonate -rock
terrain are the main components of karst topography.
S ite index
A designation of the quality of a forest site based on the height of the dominant
stand at an arbitrarily chosen age. For example, if the average height attained
by dominant and codominant trees in a fully stocked stand at the age of 50
years is 75 feet, the site index is 75.
S lickensides (pedogenic)
Grooved, striated, and/or glossy (shiny) slip faces on structural peds, such as
wedges; produced by shrink -swell processes, most commonly in soils that have
a high content of expansive clays.
S lide or slip (map symbol)
A prominent landform scar or ridge caused by fairly recent mass movement or
descent of earthy material resulting from failure of earth or rock under shear
stress along one or several surfaces.
S lope
The inclination of the land surface from the horizontal. Percentage of slope is
the vertical distance divided by horizontal distance, then multiplied by 100.
Thus, a slope of 20 percent is a drop of 20 feet in 100 feet of horizontal
distance.
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S lope alluvium
Sediment gradually transported down the slopes of mountains or hills primarily
by nonchannel alluvial processes (i.e., slope -wash processes) and
characterized by particle sorting. Lateral particle sorting is evident on long
slopes. In a profile sequence, sediments may be distinguished by differences in
size and/or specific gravity of rock fragments and may be separated by stone
lines. Burnished peds and sorting of rounded or subrounded pebbles or cobbles
distinguish these materials from unsorted colluvial deposits.
S low refill
The slow filling of ponds, resulting from restricted water transmission in the soil.
S low water movement
Restricted downward movement of water through the soil. See Saturated
hydraulic conductivity.
Sodic (alkali) soil
A soil having so high a degree of alkalinity (pH 8.5 or higher) or so high a
percentage of exchangeable sodium (15 percent or more of the total
exchangeable bases), or both, that plant growth is restricted.
Sodic spot (map symbol)
An area where the surface layer has a sodium adsorption ratio that is at least
10 more than that of the surface layer of the named soils in the surrounding
map unit. The surface layer of the surrounding soils has a sodium adsorption
ratio of 5 or less.
Sodicity
The degree to which a soil is affected by exchangeable sodium. Sodicity is
expressed as a sodium adsorption ratio (SAR) of a saturation extract, or the
ratio of Na+ to Ca++ + Mg++. The degrees of sodicity and their respective ratios
are:
Slight: Less than 13:1
Moderate: 13-30:1
Strong: More than 30:1
Sodium adsorption ratio (SAR)
A measure of the amount of sodium (Na) relative to calcium (Ca) and
magnesium (Mg) in the water extract from saturated soil paste. It is the ratio of
the Na concentration divided by the square root of one-half of the Ca + Mg
concentration.
Soft bedrock
Bedrock that can be excavated with trenching machines, backhoes, small
rippers, and other equipment commonly used in construction.
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Soil
A natural, three-dimensional body at the earth's surface. It is capable of
supporting plants and has properties resulting from the integrated effect of
climate and living matter acting on earthy parent material, as conditioned by
relief and by the passage of time.
Soil separates
Mineral particles less than 2 millimeters in equivalent diameter and ranging
between specified size limits. The names and sizes, in millimeters, of separates
recognized in the United States are as follows:
Very coarse sand: 2.0 to 1.0
Coarse sand: 1.0 to 0.5
Medium sand: 0.5 to 0.25
Fine sand: 0.25 to 0.10
Very fine sand: 0.10 to 0.05
Silt: 0.05 to 0.002
Clay: Less than 0.002
Solum
The upper part of a soil profile, above the C horizon, in which the processes of
soil formation are active. The solum in soil consists of the A, E, and B horizons.
Generally, the characteristics of the material in these horizons are unlike those
of the material below the solum. The living roots and plant and animal activities
are largely confined to the solum.
Spoil area (map symbol)
A pile of earthy materials, either smoothed or uneven, resulting from human
activity.
Stone line
In a vertical cross section, a line formed by scattered fragments or a discrete
layer of angular and subangular rock fragments (commonly a gravel- or cobble -
sized lag concentration) that formerly was draped across a topographic surface
and was later buried by additional sediments. A stone line generally caps
material that was subject to weathering, soil formation, and erosion before
burial. Many stone lines seem to be buried erosion pavements, originally
formed by sheet and rill erosion across the land surface.
Stones
Rock fragments 10 to 24 inches (25 to 60 centimeters) in diameter if rounded or
15 to 24 inches (38 to 60 centimeters) in length if flat.
Stony
Refers to a soil containing stones in numbers that interfere with or prevent
tillage.
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Stony spot (map symbol)
A spot where 0.01 to 0.1 percent of the soil surface is covered by rock
fragments that are more than 10 inches in diameter in areas where the
surrounding soil has no surface stones.
Strath terrace
A type of stream terrace; formed as an erosional surface cut on bedrock and
thinly mantled with stream deposits (alluvium).
Stream terrace
One of a series of platforms in a stream valley, flanking and more or less
parallel to the stream channel, originally formed near the level of the stream;
represents the remnants of an abandoned flood plain, stream bed, or valley
floor produced during a former state of fluvial erosion or deposition.
Striperopping
Growing crops in a systematic arrangement of strips or bands that provide
vegetative barriers to wind erosion and water erosion.
Structure, soil
The arrangement of primary soil particles into compound particles or
aggregates. The principal forms of soil structure are:
Platy: Flat and laminated
Prismatic: Vertically elongated and having flat tops
Columnar Vertically elongated and having rounded tops
Angular blocky: Having faces that intersect at sharp angles (planes)
Subangular blocky: Having subrounded and planar faces (no sharp angles)
Granular: Small structural units with curved or very irregular faces
Structureless soil horizons are defined as follows:
Single grained: Entirely noncoherent (each grain by itself), as in loose sand
Massive: Occurring as a coherent mass
Stubble mulch
Stubble or other crop residue left on the soil or partly worked into the soil. It
protects the soil from wind erosion and water erosion after harvest, during
preparation of a seedbed for the next crop, and during the early growing period
of the new crop.
Subsoil
Technically, the B horizon; roughly, the part of the solum below plow depth.
Subsoiling
Tilling a soil below normal plow depth, ordinarily to shatter a hardpan or
claypan.
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S ubstratum
The part of the soil below the solum.
S ubsurface layer
Any surface soil horizon (A, E, AB, or EB) below the surface layer.
S ummer fallow
The tillage of uncropped land during the summer to control weeds and allow
storage of moisture in the soil for the growth of a later crop. A practice common
in semiarid regions, where annual precipitation is not enough to produce a crop
every year. Summer fallow is frequently practiced before planting winter grain.
S ummit
The topographically highest position of a hillslope. It has a nearly level (planar
or only slightly convex) surface.
S urface layer
The soil ordinarily moved in tillage, or its equivalent in uncultivated soil, ranging
in depth from 4 to 10 inches (10 to 25 centimeters). Frequently designated as
the "plow layer," or the "Ap horizon."
S urface soil
The A, E, AB, and EB horizons, considered collectively. It includes all
subdivisions of these horizons.
Talus
Rock fragments of any size or shape (commonly coarse and angular) derived
from and lying at the base of a cliff or very steep rock slope. The accumulated
mass of such loose broken rock formed chiefly by falling, rolling, or sliding.
Taxadjuncts
Soils that cannot be classified in a series recognized in the classification
system. Such soils are named for a series they strongly resemble and are
designated as taxadjuncts to that series because they differ in ways too small to
be of consequence in interpreting their use and behavior. Soils are recognized
as taxadjuncts only when one or more of their characteristics are slightly
outside the range defined for the family of the series for which the soils are
named.
Terminal moraine
An end moraine that marks the farthest advance of a glacier. It typically has the
form of a massive arcuate or concentric ridge, or complex of ridges, and is
underlain by till and other types of drift.
Terrace (conservation)
An embankment, or ridge, constructed across sloping soils on the contour or at
a slight angle to the contour. The terrace intercepts surface runoff so that water
soaks into the soil or flows slowly to a prepared outlet. A terrace in a field
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generally is built so that the field can be farmed. A terrace intended mainly for
drainage has a deep channel that is maintained in permanent sod.
Terrace (geomorphology)
A steplike surface, bordering a valley floor or shoreline, that represents the
former position of a flood plain, lake, or seashore. The term is usually applied
both to the relatively flat summit surface (tread) that was cut or built by stream
or wave action and to the steeper descending slope (scarp or riser) that has
graded to a lower base level of erosion.
Terracettes
Small, irregular steplike forms on steep hillslopes, especially in pasture, formed
by creep or erosion of surficial materials that may be induced or enhanced by
trampling of livestock, such as sheep or cattle.
Texture, soil
The relative proportions of sand, silt, and clay particles in a mass of soil. The
basic textural classes, in order of increasing proportion of fine particles, are
sand, loamy sand, sandy loam, loam, silt loam, silt, sandy clay loam, clay loam,
silty clay loam, sandy clay, silty clay, and clay. The sand, loamy sand, and
sandy loam classes may be further divided by specifying "coarse," "fine," or
"very fine."
Thin layer
Otherwise suitable soil material that is too thin for the specified use.
Till
Dominantly unsorted and nonstratified drift, generally unconsolidated and
deposited directly by a glacier without subsequent reworking by meltwater, and
consisting of a heterogeneous mixture of clay, silt, sand, gravel, stones, and
boulders; rock fragments of various lithologies are embedded within a finer
matrix that can range from clay to sandy loam.
Till plain
An extensive area of level to gently undulating soils underlain predominantly by
till and bounded at the distal end by subordinate recessional or end moraines.
Tilth, soil
The physical condition of the soil as related to tillage, seedbed preparation,
seedling emergence, and root penetration.
Toeslope
The gently inclined surface at the base of a hillslope. Toeslopes in profile are
commonly gentle and linear and are constructional surfaces forming the lower
part of a hillslope continuum that grades to valley or closed -depression floors.
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Topsoil
The upper part of the soil, which is the most favorable material for plant growth.
It is ordinarily rich in organic matter and is used to topdress roadbanks, lawns,
and land affected by mining.
Trace elements
Chemical elements, for example, zinc, cobalt, manganese, copper, and iron, in
soils in extremely small amounts. They are essential to plant growth.
Tread
The flat to gently sloping, topmost, laterally extensive slope of terraces, flood -
plain steps, or other stepped landforms; commonly a recurring part of a series
of natural steplike landforms, such as successive stream terraces.
Tuff
A generic term for any consolidated or cemented deposit that is 50 percent or
more volcanic ash.
Upland
An informal, general term for the higher ground of a region, in contrast with a
low-lying adjacent area, such as a valley or plain, or for land at a higher
elevation than the flood plain or low stream terrace; land above the footslope
zone of the hillslope continuum.
Valley fill
The unconsolidated sediment deposited by any agent (water, wind, ice, or mass
wasting) so as to fill or partly fill a valley.
Variegation
Refers to patterns of contrasting colors assumed to be inherited from the parent
material rather than to be the result of poor drainage.
Va rye
A sedimentary layer or a lamina or sequence of laminae deposited in a body of
still water within a year. Specifically, a thin pair of graded glaciolacustrine layers
seasonally deposited, usually by meltwater streams, in a glacial lake or other
body of still water in front of a glacier.
Very stony spot (map symbol)
A spot where 0.1 to 3.0 percent of the soil surface is covered by rock fragments
that are more than 10 inches in diameter in areas where the surface of the
surrounding soil is covered by less than 0.01 percent stones.
Water bars
Smooth, shallow ditches or depressional areas that are excavated at an angle
across a sloping road. They are used to reduce the downward velocity of water
and divert it off and away from the road surface. Water bars can easily be
driven over if constructed properly.
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Weathering
All physical disintegration, chemical decomposition, and biologically induced
changes in rocks or other deposits at or near the earth's surface by atmospheric
or biologic agents or by circulating surface waters but involving essentially no
transport of the altered material.
Well graded
Refers to soil material consisting of coarse grained particles that are well
distributed over a wide range in size or diameter. Such soil normally can be
easily increased in density and bearing properties by compaction. Contrasts
with poorly graded soil.
Wet spot (map symbol)
A somewhat poorly drained to very poorly drained area that is at least two
drainage classes wetter than the named soils in the surrounding map unit.
Wilting point (or permanent wilting point)
The moisture content of soil, on an ovendry basis, at which a plant (specifically
a sunflower) wilts so much that it does not recover when placed in a humid,
dark chamber.
Windthrow
The uprooting and tipping over of trees by the wind.
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