620 



REPORT UNITED STATES GEOLOGICAL SURVEY. 



Product us costatus. 



Sp infer rocky montanus. 



Crinoiilal stems. 



Rhombopora lcpidoilcndroid.es. 



Hemip ro nitcs crenistria. 



Productus sp. % 



Spirifcr rocky montanus. 



Atliyei subtilita. 



Zaphrentis sp. % 



Productus sp.? 



Crinoidal stems. 



Zaphrentis sp. % 



Crinoidal stems. 



Zeptopora sp. ? 



Bhynchonella sp. ? 



Crinoidal stems. 



Productus sp. % 



Phynchonella pustulosa. 



lihynchonella rocJcymontana. 



Enomplialus sp. % 



Spirifer rocky montanus. 



Spirifer striatus. 



Spirifer (Martinia) sp. ? 



Athyris (Spirigera) subtilita. f 



Zaphrentis sp. % 



Fenestella sp. "? 



lihombopora lepidodendroides. 



Productus prattenianus. 



Mhynchonella uta. 



Spirifer striatus. 



Zaphrentis sp. 1 



Enomplialus sp. "? 



Aulopora sp. ? 



Productus costatus. 



Enomplialus luxus. 



Productus semirecticulatus. 



Spirifer rochy 'montanus. 



Spirifer (Martinia) planoconvexa. 



Station Xo. 82, on east side of the 

 Upper Portnenf Valley. 



Ridge southeast of East Fork of 

 Blackfoot River. 



Station No. 110, south of Bear Lake, 

 on east side of vallev. 



) Station 114 in Bear River Range, 

 ] west of Blooinington. 



/ Station No. 125, at Forts of Logan 

 ( River, in canon . 



Middle of Loaan Canon. 



Eastern slopes of Station 136, on 

 west side of Malade Valley. 



I^West side of the Malade Valley, 

 south of Samaria. 



! Ridge leading to Station 137, on 

 f west side of Malade Valley. 



PALAEOZOIC OROGRAPHY. 



It is manifestly impossible to enter into any extended generalizations 

 from the few facts gathered during the hasty examination of a district 

 of 13,000 square miles in one season. There are, however, a few points 

 to which I deem it necessary to call attention. 



First. The sections of Palaeozoic rocks render it evident that the sedi- 

 ments were deposited in a deep sea. The Silurian and Carboniferous ages 

 were eminently limestone-making ages in our district, and the western, 

 northern, and southern shores of the Palaeozoic sea were probably far be- 

 yond the limits of our district. The Wind River Mountains, as well as 

 the Rocky Mountains of Colorado and their northern extension, rose 

 above the Palaeozoic sea, and their western slopes probaby formed a por- 

 tion of the eastern shore line. 



Second. The Palaeozoic sediments show no unconformibility in our dis- 



