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C] • POINT LOOKOUT SANDSTONE The Point Lookout sandstone is the basal formation of the Mesa Verde ~ area. In this report, the Point Lookout sandstone is divided into two members: up of thin sandstone beds with inter-bedded shale that comprises a transitional Mancos shale: and an upper massive sandstone member consisting of thick, ma textured, medium-grained sandstone that form conspicuous cliffs in the norther 2.04.6 page 2 ~ in the Hesperus per member made nce above the beds of even- ~n of the project area. The Point Lookout sandstone is reported to maintain a rather uniform thickness of about 400 feet across the Hesperus area, but the sandstone beds at any given horizon becomeiprogressively finer grained eastward and the lower member thickens at the expense of the massive sandstone member. In the project area, the massive sandstone member of marine origin is about 100 feet thick and the lower transitional member is about 300 feet thick. MENEFEE FORMATION The Menefee formation is the middle member of the Mesa Verde Group ar complex assemblage of lenticular cross-bedded sandstone beds, gray, brown, and b beds. The formation is chazacterized by irregular bedding and rapid lateral change~~ The contact of the Menefee with the underlying Point Lookout sandstone is most places the contact is marked by a sharp break between the carbonaceous shale Menefee and the clean sandstone of the massive member of the Point Lookout. Lo eastern half of T35N, and R 12W, the basal Menefee is reported to consist of massi~ the separation is not readily made. The Menefee formation thins in an eastward direction from approximately Cherry Creek Valley. about four miles west of the Hesperus project area, to about 1 Florida River valley about 15 miles east of the project area. Most of the variations of thickness of the Menefee formation are reported tc [he more compressible shale and coal predominate the section. Locally, thickness ~ Menefee can be attributed to scouring action of the water source responsible for the overlying Cliff House Sandstone. From an area near the head of Hay Gulch in Seci R I 1 W, east to the La Plata River, the upper coal bearing horizon is significantly thi replaced by the overlying Cliff House Sandstone. This upper coal bearing horizon the upper coal seam, so prevalent in the Hay Gulch area, is completely absent. The Menefee formation is of non-marine origin throughout [he Hesperus arc petrographic impression of the formation varies with its lithologic character, but ov it is slightly less resistant than the overlying and underlying formation. d consists of a ack shales, and coal of lithology. conformable. In > and coals of the pally, through the 'e sandstones and feet in the feet in the be thinner where ariations of the disposition of the on 27, T35N, tned and apparently s scoured to where The most of the area November 1993