ILLUSTRATIONS xix 



FACING PAGE 



Plate 19 230 



Weathering Controlled by Jointing, Summit of Mt. Ktaadn, 

 Maine. From a photograph by L. H. Merrill. 



Plate 20 234 



Fig. 1, Weathered Mica Schist, coast of Cape Elizabeth, 



Maine. 

 Fig. 2, Sandstone Bored by Bees. 

 Fig. 3, Glaciated Limestone. 



Plate 21 239 



Weathering of Horizontally Bedded Jurassic Sandstone and 

 underlying thin bedded Calcareous Rocks, near Bluff, Utah. 

 From a photograph by Whitman Cross, U. S. Geological 

 Survey. 



Plate 22 244 



Fig. 1, Weathered Boulder of Oriskany Sandstone. 



Fig. 2, Concentric Weathering in Diabase. 



Fig. 3, Zonal Weathering in Argillite. 



Fig. 4, Sandstone Showing Induration Along Joint Planes. 



Plate 23 .247 



Fig. 1, Sinkhole near Knoxville, Tenn. 

 Fig. 2, Marble Beds Corroded by Water. 



Plate 24 255 



Eesiduary Quartzite, Bakalsk Iron Mines, Russian Urals. 



Plate 25 274 



Rock Disintegration and the Formation of Talus, Mount 

 Sneffels, Colo. From a photograph by Whitman Cross, 

 U. S. Geological Survey. 



Plate 26 280 



Fig. 1, Forest Destroyed by Wind-blown Sand. From a 

 photograph by I. C. Russell, U. S. Geological 

 Survey. 

 Fig. 2, Wind Drifts and Wind Erosion, White Yalley, West- 

 ern Utah. From a photograph by G. K. Gilbert, 

 U. S. Geological Survey. 



Plate 27 287 



Landslide at Rico, Colorado. From a photograph by Whit- 

 man Cross, U. S. Geological Survey. 



