ABSTRACT
The distribution of selenium (Se) in rocks and soils of the United States was studied extensively from 1930 to 1950 as part of research on Se toxicity in livestock in the western states [1-3]. Plants have also been studied as indicators of the geographical distribution of Se [4,5]. A generalized summary of Se distribution in soils of the United States [5] showed that soils in areas of the Rocky Mountains and extending into the Great Plains states are high in Se, whereas soils of both the eastern and western coastal states are low in Se. In California, the U.S. Geological Survey pointed out that the rocks of the Coast Range contain iron disulfide (pyrite) [6]. Pyritecontaining rocks of marine origin occur along the entire western margin of the San Joaquin Valley, and some of these contain significant amounts ofSe.
