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<br />• (1989°), Pitman, et. al, 19895), and Collins (19766). The closest measured section to the Roadside
<br />Mine is from the Book Cliff Mine area, 12 miles northwest (Erdmann, 1934, p. 45). Petrographic
<br />information is limited to samples taken from superficially similar sandstones (Corcoran and
<br />Cozzette) encountered in the Department of Energy's Multiwell Experiment cores from closely-
<br />spaced wells drilled south of Anvil Points, about 35 miles to the northeast. Minimal published
<br />hydrologic information for the property itself is available in Brooks (1986'), who was concerned
<br />almost entirely with overlying rocks and alluviaVcolluvial aquifers, and hydrologic characteristics
<br />can be inferred from natural gas reservoir studies of the Corcoran, Cozzette, and other related
<br />sandstones. T}te-Rollins was found to be essentially dry in the Coal Gulch area, about 25 miles
<br />northwest, and was thus~tot included in a ground water testing study being conducted there by J.F.
<br />Sato & Associates (19838).
<br />The Rollins Sandstone in the area of interest can be best described as acoarsening-upward
<br />regressive sandstone sequence, capped by a beach sandstone (Johnson, 1989, E14), although
<br />detailed examination in specific localities introduces complexities such as restricted transgressions,
<br />most likely due to local differential compaction, reduction in sediment supply, or both, and more
<br />varied environments, particularly distributary channel and related levee and overbank deposits. In
<br />the area of the Roadside Mine it can be generally described as a fine- to medium-grained white to
<br />buff sandstone, occasionally coarse-grained, especially near the top. It is predominantly quartz,
<br />with rare feldspar, common lithic fragments, some chert, and frequent coalified plant debris, the
<br />latter three resulting in a light to moderate gay color in unweathered rock. Detrital dolomite is also
<br />frequently present in varying but small amounts. Pitman, er. al. (1989, p. G23) classified the
<br />• Mesaverde shoreline-marine sandstones generally as subarkoses. Quartz grains are angular to
<br />subrounded, with degree of rounding generally increasing with grain size. The lithic component of
<br />these sandstones is made up of predominantly sedimentary rock fragments and is composed of
<br />"...partly dissolved mudstone, clay-rich shale, and siltstone clasts that have been deformed
<br />between framework grains to form a pseudomatlix." (Pitman, er, al., p. G24). A detrital matrix
<br />similar to the pseudomatrix is also commonly present, and in many places essentially cements the
<br />Rollins; the high matrix content has eliminated secondary porosity and prohibited the formation of
<br />authigenic cement in these areas (Pitman, et. al., 1989, p. G24).
<br />a Francryk, KJ., 1989, Depositional controls on the Late Campanian Sego Sandstone and implications for associated
<br />coal-fomung emaronments in the Uinta and Piceance basins: U.S. Geol. Survey Bull. 1787-F, 17 p.
<br />5 Pitman., J.K, Spencer, C.W., and Pollastro, RM., 1989, Petrography, mineralogy, and reservoir characteristics of
<br />the upper Cretaceous Mesaverde Group in the east-central Piceance basin, Colorado: U. S. Geol. Survey Bull. 1787-F, 31.
<br />6 Collins, B. A., 1976, Coal deposits of the Carbondale, Grand Hogback, and southern Danforth Hills coal fields,
<br />eastern Piceance basin, Colorado: Colorado School of Mines Quarterly, v. 71, no. 1, 138 p.
<br />~ Brooks, Tom, 1986, Geohydmlogy and potential hydrologic effects of undergrowd coal mining N the Rapid Creek
<br />basin, Mesa County, Colorado: U.S. Geol. Survey Water Resources Invest. Report 86172, 28 p.
<br />• s J.F. Sato & Associates, 1983, Impact of longwall mining on the hydrologic balance -preliminary data collection:
<br />U.S. Bureau of Mines Open-File Report 187-83, 141 p. Comments regarding absence of significant water N the Rollins here
<br />from Dorchester Coal Comparry application for a mining and reclamation permit, 1984, part 2.04.7(1), p. 10.
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