C H A P T E R I V. 



I'.i >. I . EMMOX6 



PLEISTOCENE GEOLOGY. 1 



No systematic study lias yet been made of the Quaternary phenomena 

 of the rtockj Mountain region, aor has any attempt been made to correlate 

 the surface phenomena of the plains with those of the Mississippi Valley. 



Ii is well known that tin- higher mountain regions of the Wes1 were 

 once occupied by extensive glaciers of the alpine type, which, however, 



had no connection with the continental glaciers thai covered such enor us 



areas in the more uorthern portions of the continent. In spite of this want 

 of direct connection of the former phenomena with those thai are generally 

 recognized as belonging to the Glacial period, it is fair to assume that the 

 greatest extension of these alpine glaciers was nearly contemporaneous \\ ith 

 thai of the great northern ice sheets, or continental glaciers. 



Although the Rocky Mountains of Colorado constitute the greatest 

 area of high mountain masses in the whole Cordillerau system, and its 

 higher portions bear abundant evidence of its former occupation l»v glacial 

 ice, as yet mi undoubted evidence has Keen found of the extension ni' its 

 glaciers below a le> el of 8,000 feet. As the foothill and plains region, which 

 was the subject of the present investigation, lies entirely below this level, 

 our studies, have not enabled us to trace any direct and definite connection 



1 Based on observations made lei instructions from tin- writ it. by Prof. George I.. Cannon, jr., 



of the Denver High School, during the summers of 1888 and 1889. Mr. Cannon has already published 

 an article on the " Quaternam of the Denver Basin" in the Proceedings of the Colorado Scientific 



Society. Vol. ill. p. 18. 



