426 



INDEX. 



Volcanic rocks, sub-groups of, 215. 

 Volcanoes, 133. 



age of, 143. 



erupted matters of, 136. 



mode of formation of, 140. 



number, size, and distribution 

 of, 134. 



two types of, 135. 



Water, agencies of, 17. 

 chemical agency of, 67. 

 mechanical agency of, 18. 

 perpetual ground, 68. 

 sorting power of, 27. 

 transporting power of, 26. 



Water, underground, 67. 



volcanic, 68. 



Waterfalls, recession of, 20. 

 Waves, land formed by, 50. 



nature of deposits by, 46. 



and tides, agency of, 41. 



transportation and deposit by, 



46. 



Wells, artesian, 70. 

 Winds, action of, 16. 



Yosemite Falls, 23. 



Zaphrentis (proper name), 288. 

 Zoological regions, 122, 188. 



