xviil ILLUSTEATIONS 



FACING PAGE 



Plate 11 125 



Fig. 1, Pisolitic Limestone. 

 Fig. 2, Oolitic Limestone. 



Plate 12 135 



Banded and Foliated Gneisses. 



Plate 13 150 



Fig. 1, Griaeiated and Exfoliated Granite, Cathedral Lake, in 

 the Sierras. From a photograph by G. K. Gilbert, 

 U. S. Geological Survey. 

 Fig. 2, Weathered Biotite Granite near Morrison Creek, Yo- 

 semite, California. From photograph by H. W. 

 Turner, U. S. Geological Survey. 



Plate 14 168 



Fig. 1, Honeycomb Weathering in Limestone, near Living- 

 stone, Montana. From a photograph by C. D. 

 Walcott, U. S. Geological Survey. 

 Fig. 2, Corroded Surface of Pyroxenie Limestone. 

 Fig. 3, Corroded Surface of Homogeneous Limestone. 



Plate 15 175 



Fig. 1, Diorite Boulder Split by Frost. 

 Fig. 2, Exfoliated Granite Boulder. 



Plate 16 185 



Weathered Granite, District of Columbia. From a photo- 

 graph by G. P. Merrill, 



Plate 17 199 



Weathered Diabase, Medford, Mass, From a photograph by 

 G. H. Barton. 



Plate 18 227 



Fig. 1, Exfoliated Granite in the California Sierras. From a 

 photograph by H. W. Turner, IJ. S. Geological 

 Survey. 

 Fig. 2, Rock Basin, one meter in diameter, in Granite. From 

 a photograph by H. W. Turner, U. S. Geological 

 Survey. 

 Fig. 3, Disintegrating Granite, Ute Pass, Colorado. From 

 a photograph by W. H. Jackson. 



