154 



EEPOET UNITED STATES GEOLOGICAL SUEVEY. 



TABLE OF FOEMATIONS. 



A table has been prepared emimerating the various forniations and 

 groups as found in the Sweetwater district. The thickness of groups 

 have been given from the minimum to maximum, and it has been indi- 

 cated in which portion of the district the latter is found. Generic names 

 of the fossils observed have been introduced. 



Table enumerating tlie various formations and groups as found in the Sweetwater district. 



Fossils. 



Character of strata. 



Shells of living 

 lake heds. 



g| 



§§< 



Numerous remains of Mam- 



Sand dunes, soU, loose drift and gravel . . < 



Lake beds, glacial deposits, and old river 

 drift. 



Loose, structureless conglomerate. Spread 

 over the undisturbed youajjer beds. 



Vary- 

 ing. 



Vary- 

 ing. 



10 

 to 

 400 



White, light yellow, pink, and greenish 

 marls and sands. Some beds of sand- 

 stone near base. 



1^ 





r 



It 



Numerous remains of Turtles, 

 liimnce, &c. 



FisJics and Insects in shales. 

 Plants higher up. 



Leaves in the sandstones and 

 some of the shales. 



Local deposit. Brown indurated shales 

 and marls, some sandstone and conglom- 

 erate near base. 



White, light gray, and buff calcareous 

 shales and marls ; series incomplete. 



II 



1^ 



Brown, concretionary sandstones near top. 

 Blue, gray, and white calcareous shales 

 lower down. Carbonaceous shales, sand- 

 stones, and dark shales near base. Thin- 

 ning northeast. 



Massive sandstones and shales. Eed near 

 top. Shales yellow and brown, contain- 

 ing selenite. Basalt breaking through 

 them. Coal. 



300 

 to 

 900 



1200 



to 



1400 



Highly arenaceous marls. White, yellow, 

 gi'een, red, brown, and maroon. Sand- 

 stones near base, together with heavy 

 local conglomerates. Thinning out north- 

 ward. 



500 



1700 

 to 

 1800 



600 

 to 

 650 



600 

 to 

 700 



