Soil substrate codes and geology were correlated based of bulk rock chemical compositions and characteristics. Soil substrate codes are as follows: QYA = Quaternary age younger alluvium and surficial deposits, QOA = Quaternary age older alluvium and surficial deposits, EOS = Unconsolidated Aeolian sand deposits both active and stabilized, SND = Sandstone dominated formations of all ages, SLM = Siltstone and/or mudstone dominated formations of all ages, SHL = Shale dominated formations of all ages, CLM = Carbonate dominated formations either limestone or dolomites of all ages, EVP = Evaporite units either halite, gypsum, or other saline mineral dominated formations of all ages, GSL = Metamorphic or igneous units with a dominantly silicic composition all ages, BMC = Metamorphic or igneous units with dominantly mafic composition all ages, H20 = Water, and UNK= unable to assign a substrate type.
All polygons should have a label for geologic formation (GEO_CODE). Where geologic formation codes differed across state boundaries, the originators' merging these datasets together had to decide which geologic formation code to keep. Thus, polygons that straddle state boundaries were labeled subject the originators' best professional judgement, available information associated with the source maps, and the interpretation of geologic formations from exiting Landsat TM imagery. Substrate codes were assigned to each geologic code with a look-up table appropriate for each state's geologic formation codes.
Description of Codes: GEO_CODE is from the source geology map. See source information for appropriate state. SUBS_CODE and SUBSTRATE were defined by NatureServe, and were assigned by the originator(s) of this dataset.
The following lists each SUBS_CODE and corresponding SUBSTRATE definitions identified in this dataset: QYA = Quaternary age younger alluvium and surficial deposits. QOA = Quaternary age older alluvium and surficial deposits. EOS = Unconsolidated Aeolian sand deposits both active and stabilized. SND = Sandstone dominated formations of all ages. SLM = Siltstone and or mudstone dominated formations of all ages. SHL = Shale dominated formations of all ages. CLM = Carbonate dominated formations either limestone or dolomites of all ages. EVP = Evaporite units either halite, gypsum, or other saline mineral dominated formation. GSL = Metamorphic or igneous units with a dominantly silicic composition all ages. BMC = Metamorphic or igneous units with dominantly mafic composition all ages. H2O = Water. UNK = Unable to determine substrate type.