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<br />2881 <br /> <br />The Summerville Formation is considered to be of <br /> <br /> <br />. Late Jurassic age because of its relation with the Late <br /> <br /> <br />Jurassic curtis Formation at the type locality. No <br /> <br /> <br />fossils have been reported from the Summerville. It has <br /> <br /> <br />been recognized in the project area by many geologists <br /> <br /> <br />and here has a lithology similar to the lower silty <br /> <br /> <br />member of the Summerville of Harshbarger, Repenning, <br /> <br /> <br />and Irwin (1957, p. 39-41). South and southwest of the <br /> <br />Ute Mountain area in New Mexico and Arizona, the Summerville <br /> <br />grades to sandstone. In the southwestern San Juan Mountains <br /> <br /> <br />region, the rocks considered to be equivalent to the <br /> <br /> <br />Surrunerville are called the uppermost member of the <br /> <br /> <br />Wanakah Formation. (Goldman and Spencer, 1941, p. 1759; <br /> <br /> <br />Imlay, 1952; McKee and others, 1956). In older reports <br /> <br /> <br />tt (Coffin, 1921) the Summerville was included in the McElmo <br /> <br />Formation. <br /> <br />Water supply.--The Surrunerville Formation is not an <br /> <br /> <br />aquifer. It overlies the Entrada and retards or prevents <br /> <br /> <br />infiltration of water into the Entrada and acts as a <br /> <br />confining layer; hence, water in the Entrada is under <br />artesian pressure. <br /> <br />. <br /> <br />5/ <br />