SANDSTONE DIKES OF UTE PASS. 115 



fifteen hundred feet in thickness — a remarkable complex 

 .of red and white arkose sandstones, grits and conglom- 

 erates. 4. The red sandstone series (Triassic), a 

 thousand feet or more in thickness. 5. The white, 

 variegated and gypsiferous Jurassic strata. 6. The 

 Cretaceous series, l)eginning with the massive and con- 

 spicuous Dakota sandstone. 



Each of these formations is cut off on the south by 

 the great fault which skirts the northeastern base of the 

 Pike's Peak massif. This profound displacement, which 

 must be regarded as a dominant factor in the oreological 

 structure of the region, and to which we undoubtedly 

 owe, in the main, the Manitou embayment of sedimentary 

 rocks and the exceptional elevation of the Pike's Peak 

 massif as compared with the Front Range to the North 

 of Ute Pass, gained early recognition and is clearly 

 indicated on Hayden's map of the Manitou area-, the 

 principal features of which are reproduced in the map 

 accompanying this paper. Although the traveler through 

 Ute Pass now leaves the sedimentary rocks and passes 

 onto the granite within two miles of Manitou, there is, 

 apparently, no reason to doul)t that the sedimentaries 

 were once continuous with those of the Manitou Park 

 area, which now begin a mile north of Green Mountain 

 Falls or nine miles from Manitou, and coincidentally with 

 the sandstone dikes described by Cross ; and it is alto- 

 gether prol)able that the fault by which Cross has 

 l)Ounded the Manitou Park sediments (Potsdam, Man- 

 itou limestone and Fountain series) on the southwest 

 is a direct continuation of that which, cutting across the 

 strike of the beds, is so much more conspicuous in the 

 Manitou area. This great displacement, which divides 



' Ann. Rep. U. S. Geol. and Geog. Survey, 1874, p. 40. 



