U. S. GEOLOGICAL SURVEY 



BULLETIN 707 SHEET No. 2 



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 oo mesas and terraces 



Arkosic I fragments of eranite) conglomerate 

 (Dawson arkosel 



Sandstone and shale with coal beds (Laramie formation) I 



Dark marine shale with 



J I Dark marine shale and limestone (Colorado group) ^ 

 K (a* Calcareous shale and limestone (Niobrara formation) 



L ib) Shale, limestone, and sandal 



Graneros shale 



Upper Cretaceous 



1000 

 600± 



Red and green shEde and sandstone (Moi 



Lower Cretaceoua 

 1 formation) Cretaceous ? 



Carboniferous 

 iPer^ian (?) and 

 Pemtsylvanian) 



Millsap limestone 



Limestone and quartzite ' ^''^J??"* limestone , 

 I Hardmg sandstone^ 



Granite 



Lava flows (rhyolite and basalt breccia) I 

 Andesitic breccia and tuff 



.Fault 

 * The Colorado group is 

 eastern pan of the a 

 such a subdivision practicable 



Ordovician 

 Cambrian 

 Pre-Cambrian 



