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<br />. <br /> <br />. <br /> <br />. <br /> <br />2891 <br /> <br />The Salt Wash Sandstone Member of the Morrison <br /> <br /> <br />consists of interbedded sandstone and mudstone in the <br /> <br /> <br />project area. The sandstone units consist of light- <br /> <br /> <br />greenish-gray (5Gys/l), pinkish-gray (5YR8/l). and yellowish- <br /> <br /> <br />gray (SY8/1), lenticular sandstone, commonly containing <br /> <br /> <br />thin clay stringers. The thickness of the sandstone beds <br /> <br /> <br />may range from a few feet to 20 feet. In general, the <br /> <br /> <br />sandstone units are composed of fine- to medium-grained <br /> <br /> <br />fairly well sorted clear quartz and comnlonly contain <br /> <br /> <br />quartz pebbles and green accessory minerals. The mudstone <br /> <br /> <br />units are predominately very dusky red (10R2/2) and <br /> <br /> <br />grc",nish-gr:ay (5G6/l). A fe\-i thin beds of gray platey <br /> <br /> <br />limestone have been noted. <br /> <br /> <br />~le sandstone generally is crossbedded with small- <br /> <br /> <br />scale. low-angle cross beds of fluvial origin. TI1e cross- <br /> <br /> <br />bcdded units commonl:; have a channel scour surface at their <br /> <br /> <br />base. ~1e sandstone units form small ledges betwcen the <br /> <br /> <br />less resistant mudstonc units and, where exposed in <br /> <br /> <br />McElmo Canyon, form an irregular benchlike steep slope <br /> <br /> <br />above the more massive vertical cliff of the Junction <br /> <br /> <br />Creek Sandstone. <br /> <br />!.,/ <br />