PERMIAN. 483 



and conglomerates. The next lower formation is probably a series of gypsiferous shales and 

 sandstones and the nearest locality at which such strata are known to occur is in Sinbad Valley, 

 12 miles south from West Creek. A fault running near, the base of the northeastern scarp 

 prevents a clear determination of the relations, but the gypsiferous beds are manifestly older 

 than the strata below the Dolores. These belong no doubt in the series measured on West 

 Creek. Owiag to complex folding and faulting * * * the extent and relation of the 

 gypsum-bearing beds can not be ascertained, but they are apparently some hundreds of feet 

 in thickness. 



Comparing the strata known on Grand River between the Dolores base and the Penn- 

 sylvanian limestones with the Cutler formation (Permian?) of the San Juan Mountains, it is 

 clear that the gypsiferous part of the series has no similar representative in the mountain dis- 

 trict. If such beds ever existed in the San Juan region, they were removed prior to the 

 deposition of the saurian conglomerate, and this does not seem at all unlikely, for gypsiferous 

 beds are known in the Paleoizoic red beds of northwestern Colorado, as reported by Peale. 



The grits and conglomerates of West Creek are so near their source that they differ from 

 the Cutler beds in being much coarser and more strongly arkose, but the section, seen on Grand 

 River and Fisher Creek certainly resembles in lithologic character the Cutler beds of the 

 Uncompahgre Valley below Ouray and appears to occupy the same stratigraphic position. 



The Cutler formation and the pre-Dolores red-bed strata of Grand River clearly correspond 

 to the lower part of Powell's Shinarump group — that is, to the " Permo-Carbonif erous " of the 

 Wasatch and Uinta mountains, according to the nomenclature of the Fortieth Parallel Survey, 

 or to the Permian of Dutton, in the Grand Canyon monograph. Fossils indicating a Permian 

 or Permo-Pennsylvanian age were found by the Fortieth Parallel geologists in the Wasatch 

 Mountains and by Walcott in the Kanab Valley of northern Arizona. The apparent absence 

 of fossils in most locaUties where these beds have been examined is no doubt due to the fact 

 that they are mainly continental deposits, an origin indicated by their texture. 



Concerning the section on Grand River, Cross ^^''^ says: 



Near Moab, on the northeast side of Spanish Valley, a poorly exposed section reveals about 

 250 feet of strata, mainly reddish sandy shales, between the "saurian conglomerate" [Triassic] 

 and the uppermost Pennsylvanian limestone. On Grand River about 1 mile above the Moab 

 ferry the "saurian conglomerate" reappears above the level of the river, and, as it rises grad- 

 ually to the northeast for several miles, a larger and larger section of the pre-Dolores strata is 

 exposed, but nowhere, so far as our observations go, do the Pennsylvanian beds appear, all the 

 sub-Dolores section belonging to the upper (Permian?) series of the Carboniferous. This is 

 itself evidence of a great break immediately below the "saurian conglomerate." That the 

 break represents uplift and erosion producing angular unconformity is well illustrated on both 

 sides of Grand River about 10 or 12 miles northeast of the ferry and just below the mouth of 

 Castle Creek, a stream heading on the west side of the La Sal Mountains. * * * -phis 

 unconformity * * * may be traced for about half a mile, and it was estimated that at 

 least 600 or 800 feet of beds are visibly truncated by the conglomerate in one continuous exposure. 

 The occurrence of an extensive section of gypsiferous sandstones and shales beneath the Dolores 

 conglomerate in Fisher Valley, on the northwest side of the La Sal Mountain, adds so much to 

 the beds transgressed; and a still higher series of sandstones and conglomerates is known so 

 that, altogether, it 4s estimated that not less than 1,500 and possibly 2,000 feet of Permian (?) 

 or upper unfossiliferous Pennsylvanian beds have been eroded in the locality of the section 

 first mentioned, opposite Moab. 



Returning to Cross's earlier -paper,^^^' we learn that Gane, in a trip down the 

 San Juan Valley, traced the Triassic (Dolores formation) but had " no opportunity 

 to study the underlying formation." 



