THE WORK OF STREAMS 



127 



FIG. 117. An example of unequal weathering. Granite bowlders have 

 weathered out of an easily disintegrated formation. Just south of the 

 Tropic of Cancer, on the Asiatic mainland opposite Hong Kong. (R. T. 

 Chamberlin.) 



the most part, however, it merely moves material already pre- 

 pared for transportation by other agents down to lower levels. 

 Rate of weathering. The rate at which weathering pre- 

 pares material 

 for removal 

 varies greatly 

 with (1) the char- 

 acter of the rock 

 (Fig. 117), (2) 

 the climate, and 

 (3) the rate at 

 which the waste 

 already formed is 

 removed. (1) 

 Open-textured 

 rocks with many 



i'r^n+0 Qnrl r+Viar FlG - 118 - St - Peters Sandstone, eastern Iowa. 

 Showing effects of joints and bedding planes upon 

 Cracks absorb weathering. 



