FORMER GLACIATION OF THE EASTERN SLOPE. 51 



mio;ht seem, at fii-st sio-ht, as if indicative of the fact that the 2;lacier 

 came down the northeast slope of Mount Ritter. This would be hardly 

 possible, however, for the position of the moraines to the south does not 

 indicate that the glacier ever rose as high as this ; and, indeed, so great a 

 thickness of the ice, at so low a level as 7,000 feet, oil the eastern slope, 

 Avould not be in harmony with what has been elsewhere observed in this 

 region. Besides, it seems impossible that glaciers should have passed over 

 those cones of easily movable ashes without spoiling their symmetry, which 

 has certainly not been accomplished. The advocates of the excessive erosive 

 power of moving ice certainly could not admit that these cones have ever 

 stood in the path of a glacier. It is not impossible that the granite should 

 have been thrown up froui below by volcanic forces. Certainly everywhere 

 in the Sierra lava and ashes have been projected in astonishing quantity 

 through this rock, and it would not appear that any positive reason can be 

 given wh}' some portions of the underlying gi\anite should not have come to 

 the surface with the purely volcanic materials. 



As a general rule these morainic accumulations on the eastern slope of the 

 Sierra are massive and extremely well marked. They extend out a few miles 

 from the edge of the mountains, and then come at once to a stop, the posi- 

 tion of their terminal point being as easy as possible to fix. 



In the gorge leading down from the Mono Pass, which is 10,765 feet in 

 elevation, there are abundant evidences of former glaciers, from near the 

 summit to the very foot of the cailon". The rocks are rounded, polished, and 

 grooved, and from the bottom of the mountain large piles of detrital ma- 

 terials extend out into the plain for several miles. According to Mr. King, 

 the lower portions of these moraines exhibit distinct traces of terraces, indi- 

 cating that at the time of the accumulation of these piles of detrital materials 

 Mono Lake stood at a much higher level than it now does. This condition 

 of things has received abundant confirmation from other facts observed all 

 through the region east of the crest of the Sierra Nevada. Unfortunately, 

 barometric observations were not taken along the base of these moraines, so 

 that the precise altitude of their termini above the sea, or above Mono Lake, 

 is not known ; the position of the terraces immediately upon the shores of 

 that lake, however, show it to have been, at one time, at least 600 feet 

 higher than it now is. 



All through the region at the head of the Tuolumne River the perfection 

 with which the moraines are preserved was, for the party exploring that por- 



