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occurrence of vertebrate fossil remains in the general area. <br />Lower Mesaverde (Coal Bearing Members) <br />The coal bearing members (upper and lower) of the Mesaverde formation are <br />stratigraphically between the Rollins sandstone and the barren member, with an approximate <br />700 ft. thickness completely present, except near the outcrop area. These members consist of <br />buff and grey fine- to medium - grained sandstone and grey shale. Coal occurs in minor <br />amounts in the upper part, but is considerably more abundant in the lower part. Thickness of <br />the formation varies in the area from 50 to 300 feet (Cashion 1973). Contact with the <br />underlying Rollins Sandstone is completely conformable. The sediments of the lower <br />Mesaverde member were deposited in the Late Cretaceous (77 mya) and represent regression <br />of the Cretaceous seas. <br />The environment of deposition was extremely variable, being marine, brackish, and <br />fresh water at various times. Although somewhat similar to the Dakota Sandstone, the lower <br />Mesaverde contains a greater number of coal beds, indicating that the paludal (marshy) <br />environment was considerably more extensive during deposition of the latter. Fresh water and <br />marine fossils have been found in this formation (Fisher et al. 1959). Dinosaur bones, dinosaur <br />tracks, and gastroliths have been reported from coal mines near the study area. <br />Within the general area, the formation outcrops on the faces of the mesas overlooking <br />the North Fork of the Gunnison. Outcrops tend to weather as tan to brown sandstones with <br />interspersed coal beds. Since vertebrate fossils have been recovered from the coal beds in the <br />region, the potential for the occurrence of vertebrate fossils in this formation is considered <br />good. <br />Upper Mesaverde (Barren Member) <br />The formation exposed in the study area is the upper Mesaverde. It consists of buff <br />and grey medium and coarse - grained sandstone (cliff - forming) and grey to greenish -grey shale. <br />Local thickness varies from 375 to 1400 feet (Cashion 1973). Contact with the underlying <br />lower Mesaverde Formation is conformable and visually sharp, and this Late Cretaceous <br />formation is largely undated (Berman et al. 1980). Mostly continental in formation, the upper <br />Mesaverde represents the last deposits related to the dominantly fluvial homogeneous <br />environment of the Late Cretaceous inland seas. <br />Several factors contribute to the potential of discovering vertebrate fossils in any unit, <br />including previously known occurrences and accessibility of exposures in the field. The <br />"Barren Member" is the only unit of the Mesaverde Formation exposed at the surface within <br />the project area boundary, and its surface expression as small, high, rounded, intermittent <br />outcrops nestled deeply into thickly vegetated, steep hillsides greatly limited access to any <br />outcrops. Due to the lack of previously recorded fossil findings in sediments that make up this <br />formation and the rugged nature of the exposures, the potential for finding fossils in the upper <br />34 <br />