158 



GEOLOGICAL SURVEY OF THE TERRITORIES. 



This section does not give the total thickness of the beds, as it only 

 readies to the summit of station 50. The summit of the plateau 

 beneath station 48 has about 800 or 900 feet more of beds similar to 

 those given in the section above, under No. 57. Even this thickness, 

 about 7,670 feet in all, may not represent the entire original thickness, 

 for we cannot at present tell the exact amount of erosion preceding the 

 pouring out of the basaltic covering of the two plateaus. 



The following section is summarized from Professor Cope's report 

 in the Annual Eeport of the United States Geological Survey for 1873, 

 pp. 436, 437. 



Wahsatch formation {Green River group). 



Thickness 

 in feet. 



1. Ash-colored banks, with bones of a mammal allied to the Bridger Hyopsodus, 



or Hyracotherium of the Eocene of Enrope and a number of Palvdina-like 

 shells, followed by light ash-colored beds exposed in banks, with bones of 

 Green River vertebrata. Near the top is a thin bed of lignite 140 



2. White bluffs, terminating in a high escarpment ) 



3. Thin bed of buff clay and sand-rock, with numerous shells and scattered > 100 



teeth and scales of fishes ) 



4. White bluffs 100 



5. Brilliantly colored strata extending in horizontal bands. • They are brilliant 



cherry red, white, true purple, with a bloom shade, yellow, and pea-green. 

 The lower portions are bright red and contain remains of Emys euthnetus, 

 Cope, and some borings of a worm 400-500 



6. Muddy-yellow clays and slate-rocks 200 



7. White or ashen beds, with decayed remains of mammals and turtles, also 



buff sandstones 50 



Bridger group, 



8. Mammoth buttes ; sediments with numerous mammalian remains 1, 000 



Total thickness 2,090 



The resemblance of the beds I have given in section No. 19 will be 

 seen at a glance. The following table of comparison will give the 

 relations of the two sections : 



Section No. 19, A. C. Peale. 



Thick- 

 ness. 



Prof. E. D. Cope's section. 



Thick- 

 ness. 



Layers Nos. 1 to 55, inclusive 



Layers Nos. 55 to 57 inclusive, with the 900 

 feet of additional heds not given in the 

 section 



Total 



4,170 



3,500 



Wahsatch formation, (Nos. 1 to 7, inclusive) 



Bridger group, (No. 



7,670 



Total. 



1,090 

 1,000 



2,090 



It will be noticed that the thickness on Plateau Creek is much greater 

 than that given in Professor Cope's section. Comparing section No. 

 19 with the descriptions given in the tables (page) we see the similar- 

 ity in composition of the strata. The fossils obtained could not be pos- 

 itively identified as to whether they were from the Green Eiver or 

 Bridger groups. 



The bones from the layers, Nos. 33, 39, 41, 44, 49, 50 and 55, of the 

 section No. 19 were submitted to Prof. E. D. Cope for examination. He 

 says they are " undoubtedly Eocene (Bridger or Green Biver). I find 

 species of reptiles and fishes ; the former Crocodilus, Emys, and Trionyx ; 

 thp latter Pajppiclithys? 



