Volume 21, Number 7 (July 2011)
About the cover:
Clinker-capped terraces and buttes in the Eocene Wasatch Formation of the central Powder River Basin, with foothills and high peaks of the Bighorn Mountains in the western distance. Clinker in these exposures formed by shallow exhumation and natural coal burning between ~40 and 200 ka. Photo by Pete Reiners. See related article, p. 4–9.
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