Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />288 G The thickness of the Junction Creek in the McElmo <br /> <br /> <br />Canyon area ranges from 230 to 300 feet. Its thickness <br /> <br /> <br />differs widely, owing to channeling of the formation <br /> <br /> <br />before Morrison deposition. In the water wells at Towaoc, <br /> <br /> <br />230 to 260 feet of the unit was penetrated. It thins <br /> <br /> <br />rapidly to the south, and, at Beclabito, N. Mex., its <br /> <br /> <br />direct correlative, the Bluff Sandstone, is 30 feet thick. <br /> <br /> <br />South of Beclabito, the Bluff grades into the Summerville <br /> <br /> <br />Formation. The Junction Creek also thins southwestward, <br /> <br /> <br />where, at Mexican Water, its equivalent, the Bluff, is <br /> <br /> <br />47 feet thick (Harshbarger, Repenning, and Irwin, 1957, <br /> <br /> <br />p.43). At the type locality of the Bluff Sandstone at <br /> <br /> <br />Bluff, Utah, the Bluff ranges in thickness from 200 to <br /> <br /> <br />350 feet. (Gregory, 1938, p. 58). <br /> <br /> <br />The Junction Creek is of Late Jurassic age on the <br /> <br /> <br />basis of its stratigraphic position. The Junction Creek <br /> <br /> <br />and the Bluff Sandstone have been assigned to the San <br /> <br /> <br />Rafael Group. Harshbarger, Repenning, and Irwin (1957, <br /> <br /> <br />p. 42) consider the Bluff to be a tongue of the Cow Springs <br /> <br /> <br />Sandstone in the Navajo country. Southward, from the <br /> <br /> <br />Four Corners area, the Bluff Sandstone, as well as a <br /> <br /> <br />large part of the Morrison Formation, grades into the <br /> <br /> <br />Cow Springs Sandstone. <br /> <br />gt. <br />