560 Emery — Green River Desert Section, Utah. 



lent distinctive horizon that Gregory 7 has shown is 

 equivalent in northeastern Arizona with the similar bed 

 in the Henry Mountains, and overlie beds of probable 

 Pennsylvanian age. The equivalence is further empha- 

 sized by likeness in lithology, every lithologic feature of 

 the series in the Green River Desert being, I believe, 

 susceptible of duplication on the Navajo Reservation. 

 The De Chelly sandstone, present in places between the 

 Moenkopi and Shinarump on the Reservation, is absent 

 in Green River Resert. 



The brief examination of the Moenkopi formation on 

 the borders of Green River Desert did not result in the 

 collection of identifiable fossil forms, though a limy bed 

 containing shell fragments was noted in the lower part 

 of the formation near Temple Mountain. Butler has, 

 however, collected fossils on Miners Mountain near 

 Fruita, about 45 miles southwest of Temple Mountain, 

 from a limestone about 300 feet below the Shinarump 

 conglomerate, which Girty has determined to be Triassic 

 (probably to be correlated with the Lower Triassic, 

 Thaynes and Woodside formations of the Wasatch 

 range). 8 This fossiliferous limestone is interbedded in 

 a series of reddish sandstones and shale, which, because 

 of lithology and stratigraphic position, I believe cor- 

 relative with the Moenkopi of the Green River Desert. 

 The Moenkopi is accordingly here referred to the Trias- 

 sic, though the Moenkopi of the Navajo Reservation was 

 referred by Gregory to the Permian (.1), because in that 

 area the various bits of fossil evidence obtained were 

 contradictory. 9 



Shinarump Conglomerate (Triassic). 



The Shinarump conglomerate, which unconformably 

 overlies the Moenkopi formation, is more resistant to 

 erosion than are the beds above and below, and where 

 inclined at low angles as it is under The Ledge, makes 

 a prominent bench in the topography. In San Rafael 

 Swell it is sharply upturned and forms a small "hog- 

 back." 



The Shinarump, from 80 to 100 feet thick, is generally 



7 Gregory, H. E., op. cit. 



8 Butler, B. S., Ore deposits of Utah, U. S. Geol. Survey, Prof. Paper 

 111, in press. 



9 Gregory, H. E., op. cit., pp. 30-31. 



