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
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| Figure 21 - Areas of resource categories for a flatlying coal bed based on data only from underground mined areas and drill holes. |
Created by the EERT WWW Staff.
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