• Surficial Geology of Iowa

    Raster of the surficial geology of Iowa based on the parent material interpretations of the US Soil Survey. The map is built from delineations made at a 1:15,840 scale, then converted to a 10 m resolution grid. This data set is based on the spatial information in the USDA-NRCS gSSURGO database and soil series characteristics described in the official soil series descriptions (OSD).

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  • Comparison of surficial geology maps based on soil survey and in depth geological survey

    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.

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  • Filtering Particle Size Distribution of Mixed Sediments (2012 INQUA Loess Conference)

    Most loess has unimodal textural curves, with a peak in the silt fraction. However, in thin loess areas, where loess overlies coarse-textured sediment, it often has a bimodal textural curve, due to pedoturbation. We present a method that can tease out these two textural signatures and thus, estimate the original particle size distribution of the loess. In this method the coarser sediment portion of such a “mixed” particle size distribution curve is removed, or “filtered out.” The end result is a curve (and data) that better reflect the original textural characteristics of the loess.

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  • Thin, pedoturbated, and locally sourced loess in the western Upper Peninsula of Michigan

    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.

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