6 EEPORT UNITED STATES GEOLOGICAL SURVEY. 



tation is scant and in large part dwarfed. This scantiness of vegeta- 

 tion, and the rapid removal of the debris of disintegrated rock in time 

 of rains and melting snows, and consequent flooding of the drainage- 

 channels, leaves the surface, especially that of the hill and valley sides, 

 so bare that the strata, for the rocks are all stratified, are as distinctly 

 seen as the leaves of a book. 



The geologist, therefore, may go to the top of any of the mountains 

 or higher hills and see the geological structure of the neighborhood 

 spread out below him like a well-drawn picture ; and even the geolog- 

 ical structure of the more distant parts of the landscape may often be 

 accurately determined from these elevated points of observation. 

 These conditions of the surface give great advantage to the geologist ; 

 not only insuring great accuracy in his work, but they also enable him 

 to accomplish it with extraordinary rapidity. This explanation, besides 

 setting forth an interesting fact, is also really due to those who, not 

 Ijersoually acquainted with the peculiarities of that region, may com- 

 pare the detailed reports that geologists have made upon various por- 

 tions of it with the comparatively short time they are known to have 

 "been engaged upon the field-work. 



In no humid country, where the debris of disintegrated rock profusely 

 and often deeply covers the underlying strata, can the details of geolog- 

 ical structure be so accurately ascertained, even by years of careful 

 search, as it may be done in a region like this, within a few days. 



