Chemical Analyses of Soils and Other Surficial Materials of the Conterminous United States

The following abstract was taken from the the Chemical Analyses of Soils and
Other Surficial Materials of the Conterminous United States Metadata, written
by David B. Smith, Research Geologist, U.S. Geological Survey, Denver,
Colorado. This metadata may be viewed in HTML at
"http://minerals.usgs.gov/".

ABSTRACT
This data set contains geochemical data from soils and other regoliths
collected and analyzed by Hans Shacklette and colleagues beginning in 1958 and
continuing until about 1976. The samples were collected at a depth of about 20
cm from sites that, insofar as possible, had surficial materials that were very
little altered from their natural condition and that supported native plants.
The sample material at most sites could be termed "soil" because it was a
mixture of disintegrated rock an organic matter. Some of the sampled deposits,
however, were not soils as defined above, but were other regolith types. These
included desert sands, sand dunes, some loess deposits, and beach and alluvial
deposits that contained little or no visible organic material. The samples
were chemically analyzed by a variety of techniques in the U.S. Geological
Survey laboratories in Denver, CO.

DATA
The data set contains 1,323 samples for a sampling density of approximately one
sample per 6,000 square kilometers. The data set is currently the only
national geochemical data set collected and analyzed according to standardized
protocols. The data are most appropriately used to provide information on
background concentrations of elements in soil.

ANALYSIS METHODS
The data was acquired using various chemical analysis methods. In summary the
methods used were: 1)Emission spectrography for Al, Ba, Be, B, Ca, Ce, Cr, Co,
Cu, Ga, Fe, La, Pb, Mg, Mn, Mo, Nd, Ni, Nb, P, K, Sc, Na, Sr, Ti, V, Yb, Y, Zn,
and Zr; 2)EDTA titration for Ca; 3)Colorimetric methods for P and Zn, 4)Flame
photometry for K; 5)Flame atomic absorption for Hg, Li, Mg, Na, Rb, and Zn;
6)Flameless atomic absorption for Hg; 7)X-ray fluorescence spectrometry for Ca,
Ge, Fe, K, Se, Ag, S, and Ti; 8)Combustion for total carbon; and 9)Neutron
activation analysis for U and Th.

THE DATA
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