This raster is a highly detailed (delineations made at the 1:15,840 scale) map of geologic materials at the surface, covering the entire state of Iowa. The map is based on the interpretations of the US Soil Survey, which regularly needs to assess the soil parent material in their mapping activities. The raster was generated from … Continue reading Surficial Geology of Iowa
Despite the widespread availability of relatively detailed soil maps in the USA, few areas have a surficial geology map published with as much spatial detail. This apparent gap between disciplines calls to question the accuracy of soil maps to represent the spatial distribution of surficial geologic materials. Therefore, the purpose of this research was to test the agreement between maps from these two sources.
UPDATE: The tremendous response to this blog post led to an international and interdisciplinary survey on how these terms are/should be defined. The results of that survey were combined with an in-depth review of the literature to produce an article that has now been published in Earth-Science Reviews. The article updates and refines the patterns … Continue reading Colluvium vs Alluvium
This GIS package contains a pair of spatial data sets that have been generated for the purpose of studying the physiography of the Des Moines Lobe landform region. One is a surficial geology map of the Des Moines Lobe and surrounding areas. This raster was generated from the USDA-NRCS gSSURGO spatial database. The attributes were extracted from … Continue reading Physiography of the Des Moines Lobe
County soil surveys document thin loess deposits across large tracts of Michigan’s western Upper Peninsula (UP), which we informally call the Peshekee loess. Our study is the first to examine the distribution, thickness and textural characteristics of these loess deposits, and speculate as to their origins. We introduce and describe a method by which the mixed sand data are removed, or “filtered out,” of the original particle size data, to better reflect the original textural characteristics of the loess.
The integration of soil survey maps with Geographic Information Systems (GIS) allows for an almost infinite level of collaboration across disciplines that use information related to soil databases. This study created a Quaternary geologic map by categorizing soil descriptions into a geologic context and joining the attributes with the Soil Survey Geographic (SSURGO) database in ArcGIS®. The resulting map communicates many of the spatial intricacies of the Des Moines Lobe landform with 15 map units based on geologic units.