132 CAKHONIKKKOUS FORMATIONS AND FAUNAS OF COLOKADO. 



I'liuix ali'iit to tlic Kiro and Dolores formations of Cross aiul Spencer. Possibly jjart 

 of t'.u'ir lltMiuosa formation is also included. 



DOLORES RIVER REGION. 



The district assigned to Peale for the year 1875 " was designated as the Grand 

 River district. It lies between the parallels of latitude 37° 52' and 39° 16'. On the 

 west it is limited b}- the meridian 109° 30', and on the east by the western limit of 

 the work of IS?-!, which is approximately the Gunnison and Uncompahgre river.s. 

 In addition to this, there is a narrow strip of country south of the Gunnison River, 

 from 10 to 20 miles in width, extending from meridian 107° to 107° 30'. 



It was found that over a great part of this area the Red Beds (Triassic) rest 

 immediately upon the Archeau rocks. "'In the extreme western limits of the district 

 it is probable that older formations lie between," l)ut '"there are no exposures of 

 rocks older than the upper part of the Lower Carboniferous. * * * Along the 

 western edge of the Uncompahgre plateau we have Permo-Carboniferous, and west 

 of the Dolores two places where beds of Upper Carboniferous age appear." In fact, 

 the Hayden atlas shows that the Dolores and some of its tributaries are bordered 

 with "Upper Carboniferous" rocks almost from the thirty-eighth parallel to the 

 junction of the main stream with the Colorado, and that the}^ accompany the Colorado 

 from that point westward bej'ond the one hundred and ninth meridian. lu Sinbads 

 Vallej' rocks of "Middle Carboniferous" age are shown. 



Peale's section made at the head of Salt Creek, which is about synonymous with 

 sayiiig in Sinbads Valley, is as follows (pp. 82 and 71): 



Section at head of Salt Creek. 



[tkiassic] 



Feet. 



1. Light-red sandstones, massive-i 



2. Dark-red shales ' 



3. Massive blood-red sandstones 700 



4. Brown sandstones with interlaminated red shales 300 



1, 600 



[CAKBOSIPEROUS. ] 



1. Pink and red shales with conglomeritic sandstones becoming light-colored near the base 



and containing gypsum 700 



2. Yellowish and black shales and sandstone with gypsum and salt. The creek, in passing the 



bluff where these beds are exposed, acquires a strong alkaline taste 300 



3. Space filled with shaly sandstones and, perhaps, bands of limestone. Beds for most part 



entirely concealed 3, 500 



4. Light yellowish and greenish shaly sandstones i 



5. Blue limestone with Productus, crinoids, and corals/ 



Total 4,800 



aV. S. Geol. Geog. Surv. Terr., Ninth Ann. Kept., for 1875, 1877, pp. 31-101. 



