THE DBAINAGE REVERSED. 35 



Plateau Province, and greatest in the Park Province. The Basin Province 

 was already above the sea level, but a comparatively low plain. In such a 

 condition, erosion would be slight; and as the ranges were lifted, the mate- 

 rial derived from them was deposited in the valleys, and it is probable that 

 no considerable amount was transported beyond the province into the sea, 

 and the general uplift of the province was little or no greater than the 

 change from that of the low plain near the sea level to its present elevation 

 that is, the Basin Province as a body is not the result of the difference be- 

 tween erosion and elevation ; but the ranges themselves do thus mark the 

 difference between erosion and elevation. That which was taken from the 

 mountains was added to the valleys. Much of the Plateau Province was 

 still an area of rapidly accumulating sediments long into Tertiary time ; 

 but at last the movements which began at the commencement of Tertiary 

 time succeeded in bringing the whole area not .only above the level of the 

 sea, but above the general level of the Basin Province itself; so that while 

 the Basin Province was drained into the Plateau Province in earlier Tertiary 

 time, in late Tertiary time the drainage was reversed, and the streams of 

 the Plateau Province found their way to the sea by passing through the 

 Basin Province, and many of them, especially those in the Sevier and 

 Wasatch regions which head along the old shore line, are now drained into 

 the basins which characterize the province thus designated. 



It is the opinion of Mr. llowell, and I believe also that of Captain 

 Dutton, that this drainage was in some cases reversed along the very channels 

 occupied by the ancient streams which ran from the Basin Province into 

 the Plateau lakes. In the Park Province the general upheaval was still 

 greater, and the Colorado River, which empties into the Gulf of California, 

 heads in the very heart of the Park Province and drains the greater part of 

 the Plateau Province by carrying its waters across the Basin Province. 

 While the general surface of the last two mentioned provinces was in 

 Mesozoic time not above the level of the sea, at the present time the general 

 surface is from four to fourteen thousand feet above the sea level ; but there 

 are portions now marked by great ranges which have been upheaved twenty 

 and thirty thousand feet ; but these portions during the progress of upheaval 

 suffered denudation, and a part at least of the material thus denuded was 



