122 



GEOLOGICAL HISTORY OF LAKE LAHONTAN. 



ing Hills, and at the corresponding extremity of the Jackson Range ; also, 

 at the southern terminus of the Quinn River Mountains, and about Black 

 Rock Point. All these localities were prominent headlands in the ancient 

 lake, and were swept by strong currents which brought gravel and sand 

 from the adjacent shore and deposited it on the salients of the land when 

 the currents were forced into deep water. 



A note-book sketch of the embankment at the south end of the Quinn 

 River Mountains is reproduced in the following diagram : 



Fig. 22. — Sketch of j;ravel embankments at south end of Quinn Kivcr Mountains, Nevada. 



The embankment is about 1,500 feet long, and at the point where the 

 profile was sketched is 1 00 feet broad and 40 feet high. It projects from a 

 salient where the current from Quinn River Valley left the shore on enter- 

 ing the strait between the Quinn River Mountains and the Slumbering Hills. 

 The valley at this point is about 4 miles broad, and, during the existence of 

 the ancient lake, formed a strait connecting two comparatively larg-e water- 



