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<br />Menefee Formation <br /> <br />• The iv4enefee formation is the middle member of the tvtesa Vexde <br />Group and consists of a complex assanblaoe of lenticular cross-bedded <br />sandstone beds, gray, brown, and black shales, and coal beds. The <br />formation is characterized by irregular bedding and rapid lateral <br />changes of lithology. <br />The contact of the 6fenefee with the underlying Point Lookout <br />sandstone is conformable. In most places, the contact is rtrar•ked by a <br />sharp break between the carbonaceous shales and coals of the ~.enefee and <br />tixe clean sandstone of the massive member of the Ibint Lookout. <br />Locally, ttu•ough the eastern half of T.35N., and R.12W., the basal <br />htenefee is reported to consist of massive sandstones and the separation <br />is not readily made. <br />The Slenefee formation thins in an eastward direction frorn <br />• approximately 350 feet in the Cherry Creek Valley, about foux•rniles west <br />o.f the Hesperus project area, to about 123 feet in the Florida {liver <br />valley about 15 miles east of the project area. <br />i.;ost of the variations of thickness of the 1.lenefee formation <br />are reported to be thinner where the more compressible shale and coal <br />predominate the suction. Locally thiclmess variations of the Idenefee <br />can be attributed to pouring action of the water souxo e responsible for <br />the disposition of the overlying Cliff House sandstone. From an area <br />near the head of flay Gulch in Srx tion 27, T.35N., R.11W., east to the La <br />Plata River, the upper coal bearing horiu~n is significantly thinned and <br />apparently replaced by tha overlying Cliff House sandstone. This upper <br />• - 4 - <br />