Geology of Coal: Examination of Coal Properties, Drifts, Slopes, and Shafts, Methods of Working

amount anthracite anticlines basin bench bituminous coal Brachiopod break breast carbon Carboniferous cars cent chute clay clay seams cleats coal beds coal field coal measures coal seams coking Cretaceous cross-entries cross-road crushing deposits depth Devonian distance drift drill driven eastern entry excavation fault feet thick fireclay floor fossils gangway geological grade haulage roads hoisting holes horizontal inches inclined seam iron joints layers Lepidodendron lignite limestone loaded located long-wall face lower manway material method miner mining necessary occur opening outcrop overlying packs Pennsylvania pitch placed portion Precambrian region right angles River rocks roof pressure room-and-pillar sand sandstone shaft shaft bottom shaft lining shaft pillar shale shots shown in Fig side sinking slate slope sometimes square miles strata stratum stream surface synclinal timber track tunnel undercut upper usually vary vertical wedged weight western width