RECONNAISSANCE IN COLORADO AND UTAH 661 
CARBONIFEROUS FORMATIONS 
Sedimentary formations of the Carboniferous System are but 
sparingly exposed in the eastern part of the Plateau country, erosion 
having penetrated to them in only a few places. They were found by 
Fic. 9.—View in Grand River Canyon at mouth of Castle Creek, Utah. Shows 
characteristic scarp of Vermilion Cliff sandstone. Probably about roo feet of thin- 
bedded strata below belong to Triassic and remainder to Permian (?), the uncon- 
formity between them not being exhibited. 
Peale in the valleys of Grand and Dolores Rivers and in Paradox and. 
Sindbad Valleys. While the Triassic and other Mesozoic rocks of 
the Plateau district can be traced continuously to the mountains of 
Colorado, the correlation of the Paleozoic formations depends entirely 
