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Rhode Island Soil Survey - Special Soil Features

Description of the RI Soil Survey Special Soil Features Shape File – Adhocspot.zip

Click Here to Download this file (Zipped File277 KB Zip file). After downloading extract all of the files to a folder and add the Adhocspot.shp shape file into ArcView (the coverage is in RI State Plane, NAD 83, feet coordinates -projection information is included).

These AD-HOC soil spot symbols, also called “soil special features” are used on soil survey maps to locate special areas, drainage features, and soil inclusions which were too small to delineate at the scale of mapping. The RI Soil Survey was mapped at a 1:15,840 scale with minimum polygon size ranging from 3 to 6 acres in size. In certain areas where the soil surveyor identified a special area or inclusion that had major differences in interpretations from the mapped soil in the area, a spot symbol was placed on the map.

Soil map with special features
Soil map showing the special soil features, note the wet spot symbols in the CeC map unit north of the road, these symbols identify small vernal pools.

Visit: http://soils.usda.gov/technical/handbook/contents/part627.html#05 for more information about special soil features. To download the ArcView symbol font for these features visit: http://www.mapsymbols.com/symbols2.html

 The flowing are explanations of the attribute fields for the Adhocspot_spf shape file:

featsymb

feat_name

feat_desc

GPI

Gravel Pit

An open excavation from which soil and underlying material has been removed, and used without crushing, as a source of sand and gravel.  Typically 1 to 3 acres.

MPI

Mine or quarry (pit)

An open excavation from which soil and underlying material is removed exposing the bedrock.  Also used to denote surface openings to underground mines.  Typically 1 to 3 acres.

ROC

Rock outcrop

An exposure of bedrock at the surface of the earth.  Not used where the named soils in the surrounding map unit are shallow over bedrock.  Typically 1 to 3 acres.

STV

Very stony spot

An area with more than 3 percent of the surface covered by rock fragments that are greater than 10 inches in diameter.  Typically 1 to 3 acres.

WET

Wet spot

Somewhat poorly drained to very poorly drained (hydric soil) area that is at least 2 drainage classes wetter than the named soils in the surrounding map unit.  Typically 1 to 3 acres.

Information on Special Soil Features (Ad hoc Spot Symbols) from the RI SSURGO and RIGIS metadata file:

For the RI SSURGO metadata click here: http://www.ncgc.nrcs.usda.gov/products/datasets/ssurgo/

NOTE: The special feature point file was downloaded from the SSURGO download site (http://www.ncgc.nrcs.usda.gov/products/datasets/ssurgo/), converted to shape file format, and re-projected into RI State Plane, NAD 83, feet coordinates using the ArcView Projection Utility. Cultural features such as cemeteries, escarpments, drainage, bunkers, and schools which are delineated in the published Soil Survey of Rhode Island were not digitized and are not provided on this file.

Process Description:  Special soil features appearing in the published soil survey were evaluated, amended, compiled, and digitized.  Most amendments were made to reduce the number of special soil features where the density of the special features shown in the published survey were not warranted.  The special soil features were compiled and digitized, using GRASS software, by NRCS personnel.  The NRCS, National Cartography and Geospatial Center, SSURGO Support Section imported both the soils and special soil features data for verification in ARC/INFO 7.0.4.  The data were edited.  New DLGs reflecting these changes were written with ARC/INFO 7.0.4. Process Date:  1995 Source Used Citation Abbreviations:  SCS5, NRCS2

Attribute

Attribute Label: Special Soil Features Codes

Attribute Definition: Special Soil Features Codes represent specific Special Soil Features. These features are identified with a major code, a minor code, and a descriptive label. The codes and label are assigned to the point or line assigned to represent the feature on published maps.

Attribute Definition Source: U.S. Department of Agriculture. 1993. Soil Survey Manual. Soil Surv. Staff, U.S. Dep. Agric. Handb. 18; U.S. Department of Agriculture. 1993. National Soil Survey Handbook, title 430-VI, part 647. Soil Conserv. Serv. http://soils.usda.gov/technical/handbook/contents/part647.html#00

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