730 REVIEWS AND BOOK NOTICES. 
The results have been carried on upon such a stupendous scale 
that the mind finds with difficulty the courage to grapple with them 
or attempt to explain them. And then, subsequent to the depo- 
Fig. 176. 
i N i i t dti. 
Basaltic Columns, Yellowstone, near mouth of Tower Creek. 
sition of these enormous beds of conglomerates, has been the wear- 
ing out of cañons and valleys 2,000 to 4,000 feet in depth, the 
eerie of some of the most marvellously grand and unique 
