30 Adventures in Scenery 



carries the mountain waters out upon the arid plain of the Great 

 Basin where they are lost. Lake Tahoe is fed by streams from 

 the mountains, but its waters evaporate and it has no stream 

 outlet to any ocean. It is at an elevation of 6,225 feet. A 

 beautiful mountain drive leads around the lake. 



Ice of the Glacial Period Left Its Mark 



During the Glacial Period the high region of the Sierra was 

 extensively covered by ice, snow, and neve. There are few more 

 imposing sights than the ice-swept rock-deserts of the upper 

 Rubicon and Devil's Basin, west of Lake Tahoe. The region of 

 Pyramid Peak and the Teliae range is characterized by frequent 

 glacial rock basins (cirques) separated by sharp ridges. Lakes 

 of glacial origin, in basins scooped out of the rocks, or formed 

 by morainal dams, are common in this once ice-bound region. 

 Moraines hundreds of feet in height represent the deposits made 

 by ice at the extremities of glaciers. From high up on Ralston 

 Peak a magnificent view may be had of the moraines of Devil's 

 Basin and the rock-strewn basin of the glacier that filled the 

 upper Rubicon Valley. Above rises a vast expanse of polished 

 white granitic rock (granodiorite) swept clean of any vestige 

 of soil by the great glacier. A short distance from Echo there 

 is a knob of this hard granitic rock 700 feet high rounded by 

 the moving ice, and south of this is Lover's Leap, a nearly per- 

 pendicular cliff of this granitic rock 1,000 feet high. The cliff 

 is due to the action of ice and the vertical jointing of the rock. 



Glaciers moved from the crest of the Sierra Range eastward 

 toward Lake Tahoe. The valleys in which are Fallen Leaf, 

 Cascade, and Emerald lakes were ice filled, and magnificent 

 moraines now lie alongside and at the lower ends of these valleys. 

 On both sides of Fallen Leaf Lake the lateral moraines are very 

 large and typical. That on the eastern side is from a half mile 

 to a mile in width and is 3 miles in length and 900 feet high. 

 The terminal moraines form a dam that causes the waters of 

 Fallen Leaf Lake to stand 100 feet above the level of Lake Tahoe. 



