Emery — Green River Desert Section, Utah. 561 



light-colored, having- a somewhat Nile-greenish tinge on 

 exposed faces, though locally it weathers almost black. 

 It is composed of very coarse-textured, cross-bedded and 

 massive sandstone and conglomerate. The conglomerate 

 is of two types, the one consisting of water-worn black 

 and brown quartz pebbles one-eighth to one-fourth of an 

 inch or more in diameter, the other of angular yellow and 

 drab limestone and shale pebbles. Limestone pebbles 

 appear to be absent under The Ledge, but are distributed 

 from top to bottom of the formation near Temple Moun- 

 tain and are especially prominent at the top. A diagnos- 

 tic feature is the abundance of fossil wood, some of it of 

 large size, as for example, a single trunk on Black Mesa 

 near West Pass, Elaterite Basin, which measures 15 feet 

 in length by 1 foot in diameter. The Shinarump is in 

 places saturated- with petroleum. In the Temple Moun- 

 tain region, it is the source of the radium-bearing ores 

 which occur in pockets associated with fossil wood. The 

 Temple Mountain mine is the type locality of uvanite, a 

 new vanadium-bearing mineral described by Hess and 

 Schaller. 10 



The beds just described unconformably overlie the 

 Moenkopi and constitute the "V division or middle con- 

 glomerate member of Gilbert's Shinarump group in the 

 Henry Mountain region and the Shinarump conglomer- 

 ate of other authors in the Colorado Plateaus. The 

 Shinarump is a most valuable marker, for its very distinct 

 characteristics with their remarkable similarity over a 

 wide area render it an unmistakable key-bed for correla- 

 tion purposes. No fossils were observed in the Shina- 

 rump in Green River Desert, and their exceeding rarity 

 in other places makes determination of the age of the 

 formation difficult. It has, however, been tentatively 

 regarded by Gregory 11 as probably of Upper Triassic 

 age on the basis of stratigraphic position and on such 

 meager fossil collections as have been made, and this 

 determination is accepted here. 



Chinle Formation (Triassic). 

 The Chinle formation embraces the variegated shales 

 and red sandstones between the Shinarump conglomerate 



10 Hess, F. L., and Schaller, W. S., Pintadoite and Uvanite, two new 

 vanadium -bearing minerals from Utah, Jour. Wash. Acad. Sci., 4, p. 578, 

 1914. 



n Gregory, H. E., op. cit. 



