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<br /> <br />CXF1IbIT D <br />GEOLOGY UESCRIPTIOI\ <br />Local Geolo~ry: <br /> <br />The local area is characterized by southerly dipping, <br />sedimentary rocks of cretaceous age which have been deeply eroded to the <br />north. <br />The upperrbst formation exposed locally is the Cliff House <br />• <br />Formation, cAxich is the upper member of the 6iesa Verde Group. It is of <br />marine origin and is canposed of irregular to lenticular ledges of hard, <br />fine-to-medium grained, calcarc.~~us Sandstone in softer argillt~ceous fine <br />s:rudstune unrdstone and silty shale. The top of this fon,atiun has bean <br />r~r.ove:d by erosron, leaving an average ti~rckness of 350 feet. 1'he Cliff <br />House Formation overlies the h;enefee Formation. <br />The Menefee Fornation, which is the middle member of the Pdesa <br />Venle Gx+oup is ecxnlosed of a cu+nplex assemblage of cross-bedded <br />sandstonc;s, black shales and coal beds. Up to seven coal seams have <br />been identified by the U.S. Geological .Survey. The Menefee Formation <br />has an average local thickness of 300 feet. The 1,4enefee overlies the <br />Point Lookout Formation. <br />The Point Lookout Formation, which is the basal member of the <br />Mesa Verde Group, is divided into two parts. The upper merber consists <br />of thick, massive beds of even-textured, medium-grained sandstone. The <br />• <br />