Occasionally something really eye-opening falls into your lap on a quiet afternoon that gets all your circuits humming. That was the case late Wednesday at LAM when the U.S. Geological Survey released an array of soil maps based on data it has been collecting since 2007. Simply put, the maps offer the most complete profile of the chemical and mineral makeup of U.S. soil ever produced. It is truly significant data, and the maps produced from it should be an important tool for anyone who designs, manages, or, well, just lives on the land.
Location map of the more than 4,800 sites of the sample. Courtesy USGS.
The USGS describes these maps and what they measure as follows:
Geochemical and Mineralogical Maps for Soils in the Conterminous United States (Open-File Report 2014-1082). The maps provide a visual representation of the national-scale geochemical and mineralogical variation in soils. In 2007, the U.S. Geological Survey initiated a low-density (1 site per 1,600 square kilometers, 4,857 total sites) survey of soils of the conterminous United States. Three samples were collected at each site from the surface down to approximately 1 meter. In total, more than 14,400 soil samples were analyzed for 45 elements and 9,575 samples were analyzed for major minerals. The maps released today were created using data sets from the survey.
The data sets, which were released in October 2013 by the USGS, provide a baseline for the abundance and spatial distribution of chemical elements and minerals against which future changes may be recognized and quantified.
The maps speak for themselves, and as you pore over the report you’ll want to dig into the data right away. But (nearly) every big data set has a person behind it, and the USGS also published a nice piece on its blog that talks about the process of collecting the data from the 4,800+ sites and some of the people who did that work. Kevin Bamber, then an undergraduate at the University of Missouri, worked on the sampling and picked up a little local knowledge along the way. “A guy in Louisiana said we could dig on his property because it was a full moon and that anytime you dig a hole when there’s a full moon, you always have more than enough dirt to fill the hole. We really picked the right day.”
All images from Smith, D. B., Cannon, W. F., Woodruff, L. G., Solano, Federico, and Ellefsen, K. J., 2014, Geochemical and mineralogical maps for soils of the conterminous United States: U.S. Geological Survey Open-File Report 2014–1082, 386 p., http://dx.doi.org/10.3133/ofr20141082. Courtesy the USGS.
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