U. S. GEOLOGICAL SURVEY 



BULLETIN 707 SHEET No. 4 



GEOLOGIC AND TOPOGRAPHIC MAP 



OF THE 



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 



1922 



EXPLANATION 



A 



A Mountain grlaciera as they were during the Great Ico Age Pleietoci 



B Gravel, sand, and clay ^teS 



J Dark marine shale IMancoe shale) { 



M Brown sandstone (Dakota sandstone) 



N Variegated shale and sandstone (Gunnison formation) 



P Brick-red sandstone 



R Red sandstone and shale (Maroon formation) 



S Red sandstone, conslomerate, and shaletWeber formatJon) 



■Upper CretacAous 



j Parti ni 



Limestone and 'White limestone 

 quar..ite j l„„„ ,„»rui„ <s,„.tth 

 I quartzite ) 



Lava flows (basalt) 



Pre-Cambrlan 

 Tertiary 



