300 



HOBBS— THE EVOLUTION AND THE 



[April 24, 



urement of the rate of uplift, because the level of the water can be 

 made use of for the zero point. There are, however, other available 

 means for investigating the rate of continental uplift. In arid and 

 semi-arid regions, such as the Great Basin of the United States, the 



f^j? 



Fig. 7. Elevated shore on the coast of California showing marks of wave 

 action. (After Fairbanks.) 



rare but violent storms cause torrents in the streams which de- 

 bouch upon the plains from the mountain fronts, and so broad fans 

 and aprons are there built up. Now if the uplift of the range goes 

 on more slowly than the alluviation along its borders, the mountain 

 front deposits will bury and hide the escarpments which are opened 

 at the time of each successive uplift. If, on the other hand, the 



