THE PHYSICAL GEOLOGY OF THE GRAND CANON 



DISTRICT. 



By Clarence E. Dutton. 



CHAPTER I. 



THE PLATEAU PROVINCE. 



The investigations made by this division of the Geological Survey 

 during- the last two years have been pursued with the object 'of increas- 

 ing our knowledge of the physical and historical geology of the West 

 and have had little relation to economic interests. The field of labor is 

 one of the most impressive and instructive in the world — impressive by 

 reason of the magnificent scale on which certain processes of nature 

 have operated, and instructive because the causes, methods, and results 

 of those processes are revealed with a distinctness which is unparalleled. 

 This field comprises the Grand and Marble Canons of the Colorado and 

 the regions which drain into them. To the entire tract, comprising an 

 area of more than 13,000 square miles, I have given the name of the 

 Grand Canon District. 



The lessons which the geologist finds in this district are many, but the 

 most conspicuous one embraces those subjects which are included under 

 the nearly synonymous names "Land Sculpture," " Denudation," 

 "Erosion." These processes operate upon the land unceasingly, carv- 

 ing out mountains and valleys and giving shape and character to the 

 earth's surface. They represent the work done upon the land by the 

 winds and rains, by Mowing water, by the chemical reactions of the at- 

 mosphere and of organic life. These processes are operative almost 

 everywhere, and their results in the lapse of immense periods of time 

 attain magnitudes, the statement of which may astonish the ordinary 

 reader and perhaps excite his incredulity, but which at length appear 

 veritable when tested by geological research and deduction. In no 

 other portion of the world are the natural laws governing the processes 

 of land sculpture exemplified so grandly; nowhere, else are their results 

 set forth so clearly. The interest excited by the grandeur of the sub- 

 jects is intensified, and the value of the lessons enhanced, by the ex- 

 ceptionally intelligible manner in which their materials are presented 

 for study. 



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