usgsdrill-hole data, in feet. gl—ground level elevation r—rock interval c—coal interval nr-n0...
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- USGSdrill-hole data, in feet. GL—Ground level elevation R—Rock interval C—Coal interval NR-N0 Record TD-T0tal depth DRILL-HOLE DATA SYMBOLS *—Measured coal thickness ND—No
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Post on 15-Aug-2021
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