U. S. GEOLOGICAL SURVEY 



BULLETIN 707 SHEET No. 1 



GEOLOGIC AND TOPOGRAPHIC MAP 



RIO GRANDE ROUTE 



From Denver, Colorado, to Salt Lake City, Utah 



Compiled from United States Geological Survey atlas 

 sheets and reports, from railroad alinements and pro- 

 files supplied by the Denver & Rio Grande Western 

 Railroad Co., and from additional information col- 

 lected with the assistance of that company 



PREPARED UNDER THE DIRECTION OF 

 GEORGE OTIS SMITH, DIRECTOR 



EXPLANATION 



Gravel 



Consrlomerate deposited by 

 (Castle Rock conglomerate) 



ArkoBic (frasmenta of granite) 

 conglomerate (Dawson arkose) 

 " sar Denver the beds equ " 

 irkose are divided into 



Shale and sand (&nde) 

 (Denver formatdonl 



1 Bhale and sandstone 



White and red aandBtone, red ! Lykina formation 

 shale and gypsum at top | Lyons sandstone 



Mainly white arkoaic sand- 

 stone (Fountain formation) 



Limestone and 



Millsap hmcEtone 



Age Thick nee 



in feet 



Pleistocene 



Tertiary iOW/ocene) 300 



2,000 



,■ Tertiary (Eocene) 



! 800± 



I 700 



L200 



Upper Cretaceous 



1,000 



Lower Cretaceous 

 Cretaceous ? 200 



Carboniferous 

 ( MieaisBippian) 

 Ordovician 

 Cambrian 



Pre-Cambrian 



Y Lava flows ( basalt and rhyolite) 

 Fault 



