OBLITERATED CONTINENTS. 147 



vouiaii and Carboniferous rocks. It is a basin a hundred 

 miles in diameter and a thousand feet in depth. On the 

 east and the west, on the north and the south, the same 

 succession of rocks rises in the bounding wall. There 

 can be no error in my conclusion that these formations 

 were once continuous from side to side. Here, then, is 

 another example of the wastage of the land. The central 

 mass of Tennessee was needed to build up the Cretaceous 

 and Tertiary formations as a foundation for Alabama and 

 Mississippi. 



Still, the most gigantic examples of denudation occur 

 in the far west. The canons of the Colorado, made famous 

 by the explorations of Newberry and Powell, are river- 

 gorges cut six thousand feet deep through the rocky forma- 

 tions of the country. All the lateral affluents of the 

 Colorado have dug similar trenches. They intersect the 

 surface in every direction, and render it almost impassa- 

 ble. Of these gorges Joaquin Miller writes: 



" Down in a canon so cleft asunder 



By saber stroke in the young world's prime 

 It looks as if broken by bolts of thunder, 

 Riven and driven by turbulent time." 



So/igs of the Sierras. 



The soils are washed away; the naked rock bakes in the 

 summer sun, and no cooling shower mitigates the fervor 

 of the climate. This desert of the continent was once its 

 garden. The ruin has been wrought by the same agen- 

 cies which have desolated Palestine till the white bones 

 of the hills protrude where vineyards once blushed, and 

 olive trees cast their delicious shade. It was the same 

 agency which is preying to-day upon the farms of New 

 York and New England, and is planning to skin the soils 



