THE CAPRICORNS, MAMMALS OF AN ASIATIC 



TYPE, FORMER INHABITANTS OF 



THE PIKE'S PEAK REGION. 



[A popular l(»cture delivered before the (^olorailo ColleRe Scieiititic Society on the 

 27th of October, 1899, and here reprinted with some revision from the Coluntdo 

 Spriiifis (uizi'tte of NovemlM^r 12th, ISW.] 



By F. W. Craoin. 



As most of my audience are aware, the granite of the Rockj' 

 Mountains, though commonly building our highest peaks, has 

 been raised to such elevated positions from an origin deep 

 down in the earth's crust beneath the stratified rocks. 



These latter members of the earth-crust have been depos- 

 ited almost wholly by water, largely oceanic, in small part 

 fresh, as mechanical, chemical and organic sediments, long 

 since consolidated into rock, that covered the granite like a 

 series of thick, more or less nearly horizontal blankets. 



The upward movement is attested by a thousand basset 

 edges of strata, of which the Gateway of the Garden of the 

 Gods and the hog-backs north and south of Colorado City are 

 conspicuous examples, upturned by the ascending portion of 

 the granite, and which still are seen, though profoundly cut 

 down and reduced to the merest remnants, the mountain- 

 blanket having been almost wholly cut away in the case of 

 Pike's Peak itself, by erosion. 



The granite and its burden of stratified rocks were thrown 

 into mountain folds in the region of the Rockies chietly at 

 the close of the Cretaceous age, the last of the three ages of 

 the great Mesozoic era; which means that, for the most part, 

 the Rocky Mountains were born at the end of the ocean's 

 sway over interior North America, though that sway, prior to 

 that time, had not been uninterrupted, for the Pike's Peak 

 region stood above the sea during parts of at least three earlier 

 geological ages — the Devonian, the Carboniferous and the 

 Jurassic — and probably during parts, also, of others, as is 

 witnessed by the absence from it of Devonian rocks (sedi- 

 ments), the presence near Manitou of thick Carboniferous 



