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GRAND JUNCTION PIPE <br />Surficial Geology Investigation, <br />September 13, 2000 <br />Bradbury Pit H, Southeast of Whitewater, Colorado <br />Page 3 <br />Primarily well rounded, basaltic cobbles which are derived from the upper basalt rocks on Grand Mesa and are believed to <br />correlate with the Pre-Bull Lake Quaternary deposit mapped by Yeend (U.S.G.S. 1969). This coarse grained gravel and <br />cobble is the deposit to be extracted from this pit. <br />This particular tract is underlain by the Mancos Shale Formation of Cretaceous Age. The Maneos Shale is considered to <br />be bedrock in this area. Based upon structural geology mapping in this area, it is believed the base of the Mancos Shale <br />is near the flow line of Indian Creek, to the southwest of this site. The Mancos Shale is believed to be approximately 130 <br />to 170 feet thick in this area. The Mancos Shale in this lower portion, immediately above the Dakota Formation, contains <br />significant developments of silt and sand. The Mancos Shale is generally fiactunxl, often to the point of being fissured and <br />may exhibit significant vertical permeability along these fractures and some horizontal permeability along the siltstone and <br />sandstonc beds. <br />GROUND WATER <br />During some periods of a calendar year, some ground water may be present beneath the alluvial gravels and cobbles. This <br />water would be a seasonal, perched water table on top ofthe Mancos Shale. Due to the geometry of this ridge, it is believed <br />any waters m the gravel and cobble would originate from snow melt or intense periods of pr?ecipitath <br />on. s It is believed that <br />any Perched water which would develop on this ridge would W rather thin and would rapidly drain away. <br />A true ground within the Burro ?r can often times be encountered in the lower sandstones of the Dakota Formation and underlying sands <br />Canyon and Summerville Formations. The upper member of the Dakota Formation is believed to be 130 <br />to 170 feet below the present ground surface at this site. It is reported that some relatively shallow wells have been drilled <br />in this area. In addition, shallow springs are !mown to exist in the Indian Creek drainW Homestead, southwest of this site. h is not known if these west of the Bean Ranch <br />springs or wells <br />actually, <br />penetrate waters are just the result of accumulations in the Indian Creek alluvium into true ors or if these <br />SURFACE WATER <br />The tract is I=IW at the top of a ridge line. Drainage in this area is generally off the property <br />The site is not located within r to the north, west and south . <br />mapped or suspected flood plains. The flood plains of Indian Creek to the south and Kannah <br />Creels to the north are between 80 to 160 feet below the elevation of this tract. <br />ECONOMIC GEOLOGIC DEPOSITS <br />The significant economic deposit on this site is the alluvial gravels and cobbles. Portions of this ridge have been mired in <br />the past, most notably in conjunction with construction of US Highway 50 and the DOE Mill Tailings Hall Road to Cheney <br />Reservoir disposal site. <br />This tract is approximately 12 miles east northeast of the Unaweep Mining District which contains significant amounts of <br />copper and minor amounts of minor silver and gold. In general, activity of the Unaweep Mining District was declining to <br />intermittent by 1970.