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_ the B and Middle beds (which are mined) , is medium-volatile <br />' • bituminous in rank (22 to 23 percent) ; the upper, unmined <br /> coal zone is high volatile (.31 to 33 percent) . <br /> All three coal zones are strong coking and <br /> possess excellent qualities for the production of blast- <br /> furnace coke. The coking qualities of the coals are second- <br /> arily dependent upon original plant material and peat-swamp <br /> conditions . However , rank, or degree of metamorphism, is <br /> the primary control. <br /> Heat resulting from depth of burial and <br /> acting over long periods of time is the principal factor in <br /> coalification. The most easily identifiable parameter <br /> indicating the degree of coalification is the general decrease <br /> in volatile-matter content (or increase in rank) with depth. <br /> Apparently , heat from the intrusive activity (thought to <br /> have been laccolithic) elevated the rank of the coal beyond <br /> that which it could have reached due to the depth of burial <br /> alone. <br /> Coal rank is uniform throughout the basin, <br /> but decreases to the north and south, indicating the effects <br /> of the Iaccolith are responsible . The lower rank of the <br /> upper coal zone probably results from the lower temperature <br /> reached due in part to greater distance from the heat source . <br /> (Collins , 1977) <br /> Four distinct coal beds have been identified <br /> in the strata of the Coal Basin anticline . In addition , a <br /> 14 <br />