478 CROSS AND HOWE — RED BEDS OF SOUTHWESTERN COLORADO 



The Permian strata thus described are overlain by " a very coarse, 

 almost conglomeratic sandstone," some 50 feet in thickness, which Dut- 

 ton correlates unhesitatingly with the "Shinarump conglomerate" (a 

 particular conglomerate within the Shinarump group), referring to the 

 fact that it is persistent and uniform in aspect wherever it appears 

 throughout the plateau country of Utah and Arizona. He does not 

 further describe it in this report. 



Following Walcott, the conglomerate thus identified as the Shinarump 

 in the Zuni plateau is considered by Dutton as the basal stratum of the 

 Trias. Above it occur some 1,600 feet of u sandy shales," also referred 

 to the " Lower Trias." The lower 650 feet of these beds are almost 

 exactly like the Permian below, while the upper portion is of lighter 

 color. 



Succeeding the " Lower Trias " shales comes the " Wingate sandstone " 

 formation, 450 feet in thickness and bright red in color. Dutton de- 

 scribes it as " in reality a group or subgroup of sandstone in which the 

 lines of bedding are generally, but not always, effaced. Sometimes, 

 however, the partings are almost obliterated, so that the edge of the 

 entire subgroup is presented as a single indivisible member. Some- 

 times a portion of the partings is effaced, and a part is so presented. 

 Sometimes partings are seen to divide the whole of it into a series of 

 beds varying in thickness from a yard or two to 20 feet. Most fre- 

 quently there will be at least 250 feet presented without subdivision, as 

 a vertical wall." Of importance to the present discussion is the apparent 

 absence of cross-bedding. As to correlation, Dutton says : 



"This formation is without much doubt the equivalent of the Vermilion Cliff 

 series in southern Utah," where it attains a thickness of more than 1,000 feet. 

 He also remarks that "out of it have been carved the most striking and typical 

 features of those marvelous plateau landscapes, which will be subjects of wonder 

 and delight to all coming generations of men. The most superb canyons of the 

 neighboring region, the Canyon de Chelly and the del Muerto, the lofty pinnacles 

 and towers of the San Juan country, the finest walls in the great upper chasms of 

 the Colorado, are the vertical edges of this red sandstone." 



Above the Wingate sandstone comes the formation generally charac- 

 terized by Newberry as the " variegated marls," but described by Dutton 

 as prevailingly arenaceous and named the " Zuni sandstones." This 

 formation is 800 to 1,300 feet in thickness. 



"It is wonderfully banded and variegated in color. Many pages might be 

 written descriptive of the changes of color which it' presents, not only as between 

 different beds in the same section, but as between the same beds in different sec- 

 tions. " 



