Coal Resource Classification System of the U.S. Geological Survey
By Gordon H. Wood, Jr., Thomas M. Kehn, M. Devereux Carter, and William C. Culbertson
GEOLOGICAL SURVEY CIRCULAR 891
Figure 3 - Flow chart showing hierarchy of coal resources and criteria for distinguishing resource categories |
Created by the EERT WWW Staff.
U.S. Department of the Interior, U.S. Geological Survey
URL: http://pubs.usgs.gov/circ/c891/figures/figure3.htm
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Last modified: 11:30:10 Mon 31 Mar 2003
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