RELICS OF MAN IN THE GLACIAL PERIOD. 299 



results. At present I can only say that the amount of 

 erosion since the lava eruptions of western Idaho is not 

 excessive, and very likely may be brought within a period 

 of from ten thousand to twenty thousand years. The 

 enormous erosion in the canon of the Snake Eiver, near 

 Shoshone Falls, in central Idaho, is doubtless of a much 

 earlier date than that in the Boise Eiver, near Nampa. 



The disturbances created in this part of the valley by 

 the bursting of the barriers between the glacial Lake 



Fig. 97.— Map showing Pocatello, Nampa, and the valley of Snake Eiver. 



Bonneville and the Snake River, already described (see 

 above, page 233), have not been worked out. There can 

 be no doubt, however, that interesting results will come 

 to light in connection with the problem ; for Pocatello, 

 the point at which the debacle reached the Snake River 

 plain, is about 2,000 feet higher than Nampa, and 350 

 miles distant, and the water must have poured into the 

 valley faster than the river in its upper portion could have 

 discharged it. By just what channels the mighty current 

 worked down to the lower levels on the western borders 

 of the State it would be most interesting as well as in- 

 structive to know. 



A study of the situation in Tuolumne and Calaveras 



