Abstract:
This dataset contains the mean depth to bedrock derived from the State Soil Geographic (STATSGO) soils data compiled by the Natural Resources Conservation Service (NRCS) of the U.S. Department of Agriculture.
The location of bedrock with respect to the land surface is often needed in surface and subsurface environmental modeling applications. The STATSGO database contains information on the range of depth-to-bedrock for each map unit component.
Supplemental_Information:
The information below was compiled from the following web page:
http://www.essc.psu.edu/soil_info/index.cgi?soil_data&conus&data_cov
The mean depth-to-bedrock for each STATSGO map unit was computed by first calculating the mean depth-to-bedrock for each component in the map unit using the ROCKDEPL (low) and ROCKDEPH (high) values from the STATSGO Component table. In some cases, the Layer table entries for the component specified a non-rock layer extending below the depth specified by ROCKDEPL/H; however, no attempt was made to adjust the mean bedrock depth for these cases.
The mean bedrock depth for the entire map unit was then computed as the weighted average of the mean depth-to-bedrock for each component, weighting each component by the percentage of the map unit area as given by the COMPPCT value. The average values were rounded to the nearest centimeter.
Many STATSGO Component table entries for depth to bedrock used 60 inches (152 cm) to indicate that bedrock was not encountered within this distance of the surface. As a result, the mean depth-to-bedrock values should be used primarily to identify mapunits in which bedrock may be encountered at depths shallower than 152 cm.
The location of bedrock with respect to the land surface is often needed in surface and subsurface environmental modeling applications. The STATSGO database contains information on the range of depth to bedrock for each map unit component.
To increase compatability with different types of data analysis software, the dataset is available in several different data file formats. These include both Arc/Info polygon format and a gridded version at 1 km resolution; the latter is available in both Arc/Info grid format and as a two-dimensional array of 8-bit unsigned binary integers. The description of dataset files provides additional details on formats, the data files asociated with each format, and instructions for file retrieval.
For the gridded version of the dataset, any 1-km grid cell which contains portions of two or more mapunits was assigned the mean depth to bedrock for the mapunit which occupies the largest fraction of the cell. For the Arc/Info grid version, the mean depth to bedrock may be accessed using the mapunit serial numbers associated with each STATSGO mapunit; the mean depth to bedrock has been incorporated into the Value Attribute Table (VAT) entry for each mapunit.