156 



EEPOET UNITED STATES GEOLOGICAL SUEVEY. 



Tahle enumerating the various fojfnations and groups, ^-c. — Continued. 



We find that in the Sweetwater district the total maximum thickness 

 of sedimentary deposits amounts to more than 16,000 feet. The esti- 

 mates upon which the thickness of Archaean groups are based must ne- 

 cessarily be iucomplete, but I believe that the figures given approach to 

 true dimensions as closely as is possible. Were the structure of chains 

 and ranges perfectly open, more reliable results could be obtaiued. 



