BULL. GEOL. SOC. AM. 



VOL. 19, 1907, PL. 21 





-^^3 



EXPLANATION 



5^ 



>J/r^ 



^ 



Eocme-Oliaocene-Miocene 



Montana sandstone 



(and overlying beds) 



Pierre shale 

 Niobrara formation 



Benton shale 



Cleverly sandstone 

 Morrison shale 



Sundance formation 

 Chugwater formation 



'Red bed/' 



Casper formation 

 PRE-CAMBRIAN 



20 25 Milai 



^ 



Snilc 

 10 15 



'm: 



/,V)jli>,lV.i.<i.pl^ 



. L'.>^'ij..-i:JiLli 



I ROCK KIVER'i 



/^^ 



^'.^ 



^^ 





X-'u 









^ 





J 



I 







ilUI!l-.l.[. i;> I /iOH-!-<<'7J7 





GEOLOGIC MAP OF SOUTH-CENTRAL WYOMINQ 



By N. H. Darton 



I 



