WEATHERING AND RATE OF WEATHERING 179 



References : 



1. 1304: 18-19. Air, Water, Rock. 



2. 1601 : 27-28. The Origin of Soil. 



o. 1202 : 150-154. Principles Involved in Rock Weathering. 



6. 1208 : 10-23. Erosion by Air and Water. 



c. 1302 : 29-32. The Earth Crust. 



d. 1307 : 24-25. The Rock Mantle and its Movements. 



e. 1608 : 24-28. The Source and Production of Soil. 

 /. 1612 : 1-4. The Earth's Clothing. 



127. WEATHERING AND THE RATE OF WEATHERING 



The changes which occur in the earth's crust, whether they 

 be those of erosion or chemical changes, are all classified under 

 one heading, Weathering. The earth is very different from 

 what it was when it first cooled off, both in shape and in its 

 surface features, as well as the character, or make-up, of its 

 surface. We may classify these under Changes in the Surface 

 of the Earth, Section 126, but for purposes of study they are 

 taken separately. See Section 129, Erosion. 



When it first began to rain, that is, when water could exist, 

 even in the atmosphere of the earth, as a liquid, the enormous 

 rainfall accomplished an erosion of the rocks which is in- 

 credible when we think of the effects of a modern rainstorm. 

 Then, also, as the water wore off the surface of the earth, the 

 material worn off formed a sort of protective covering, and 

 thus the rate of weathering became less as time went on. 

 Nevertheless, water still continues to produce more rapid 

 results than any other single agent of weathering. 



References : 



1. 1205 : 5-38. The Work of the Weather. 



2. 1304:38-40. Weathering. 



3. 1304 : 41-42. Rate of Weathering. 



