620 



EEPORT UNITED STATES GEOLOGICAL SUEVEY. 



Productus costatus. 



Spirifer rocJcymontanus. 



Crinoidal stems. 



Uliomhopora lepidodendroides. 



Hemipronitcs crenistria. 



Froductus sp. 1 



Spirifer roclcymontanus. 



Athyei suMilita. 



Zaphrentis sp.? 



Productus sp.? 



Crinoidal stems. 



Zaphrentis sp. ? 



Crinoidal stems. 



■Leptopora sp. ? 



Bliynclionella sp.? 



Crinoidal stems. 



Productus sp. "? 



EhyncJionella pustulosa. 



Rliynclionella rockymontana. 



Enomplialus sp. ? 



Spirifer roclcymontanus. 



Spirifer striatus. 



Spirifer (Martinia) sp. ? 



Atliyris (Spirigera) subtilita, ? 



Zaphrentis sp.? 



Fenestella sp. ? 



Rhombopora lepidodendroides. 



Productus prattenianus. 



Rhynchonella uta. 



Spirifer striatus. 



Zaphrentis sp. ? 



JEnomphalus sp. ? 



Aulopora sp. ? 



Productus costatus. 



JEnomphalus luxus. 



Productus semirecticulatus. 



Spirifer roclcymontanus. 



Spirifer {Martinia) planoconvexa. 



Station Ko. 82, on east side of the 

 Upper Portneuf Yalley. 



Eidge southeast of East Fork of 

 Blackfoot Eiver. 



! Station No. 110, soutli of Bear Lake, 

 [ on east side of valley. 



) Station 114 in Bear Eiver Eange, 

 ] west of Bloomington. 



/ Station ]S^o, 125, at Forks of Logan 

 ( Eiver, in canon. 



> Middle of Logan Caiion. 



Eastern slopes of Station 136, on 

 west side of Malade Valley. 



West side of the Malade Valley, 

 south of Samaria. 



Eidge leading to Station 137, on 

 west side of Malade Valley. 



PALEOZOIC OEOGKAPHT. 



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 mUes in one season. There are, however, a few points 

 to which I deem it necessary to call attention. 



First. The sections of Palseozoic 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 Eiver Mountains, as well as 

 the Eocky Mountains^ of Colorado and their northern extension, rose 

 above the Palaeozoic sea, and their western slopes x3robaby formed a por- 

 tion of the eastern shore line. 



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



