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<br />o <br />o <br />N <br />....' <br /> <br />Mesaverde group is the sandy upper member of the Blackhawk Formation (Fisher, Erdmann, <br />and Reeside, 1960). In most places this unit forms a cliff that is continuous with the overlying <br />Castlegate Sandstone, The Castlegate Sandstone is buff to brown and gray, slightly shaley in <br />places, and medium to thick bedded. The Blackhawk Formation here is about 50 feet thick, and <br />the Castlegate Formation is about 90 feet thick. <br /> <br />Above the Castlegate lies 190 feet of shale with some thin bedded sandstone layers that comprise <br />the Buck Tongue of the Mancos Shale. On top of the Buck Tongue lies about 170 feet of the <br />Sego Sandstone. The Sego Sandstone is made up of buff to gray, massive to thin bedded, fme <br />grained to shaley sandstone. The Nelsen Formation (295 feet thick) overlies the Sego Sandstone, <br />and exhibits gray to brown and buff variable layers of shale, sandstone, and coal. Above the <br />Nelsen is the 470 foot thick Farrer Formation at the top of the Mesaverde group. The Farrer is <br />similar to the Nelsen, but lacks coal, and has a distinct greenish tinge in its shale layers. <br /> <br />The Cretaceous Tuscher Formation overlies the Farrer Formation and contains light-colored <br />sandstone beds with minor shale layers. It can be distinguished from the Farrer by its lighter <br />color, and from the unconformably overlying Wasatch Formation by its lack of the <br />predominately red varicolored shales that characterize the Wasatch. <br /> <br />The Paleocene-Eocene Wasatch Formation (up to 1600 feet thick) makes up the top of the Book <br />Cliffs, and consists of bright varicolored shales and cliff-forming sandstones. A conglomerate <br />layer up to 50 feet thick is present at the base of the Wasatch in some areas, but totally absent <br />in others. The highest elevations at the north end of the Sagers Wash drainage basin are part <br />of the Wasatch Formation, along with isolated remnants of the overlying Green River Formation <br />which contains brown and gray sandstone, siltstone, oolitic limestone, and green shale. <br /> <br />Quaternary deposits within the Sagers Wash area include alluvial, colluvial, and eolian deposits,fand thin gravels capping pediment or terrace remnants, Some of these thin gravels near the <br />lower end of the drainage basin may have been deposited by the Colorado River. <br /> <br />9 <br />