612 THE ICE AGE IN NORTH AMERICA. 



fianks, where erosion has carved them in typical mountain 

 forms. . . . The date of the Bonneville flood is the geologic 

 yesterday, and, calling it yesterday, we may without exag- 

 geration refer the Pliocene of Utah to the last decade the 

 Eocene of the Colorado basin to the last century, and re- 

 legate the laying of the Potsdam sandstone to prehistoric 

 times."* 



Mr. Gilbert believes that all this is attributable to suc- 

 cessive elevations of the region, with an intervening subsidence. 

 The evidence of a post-tertiary elevation is found "in the 

 deeply submerged channel near Cape Mendicino," while the 

 proofs of a subsequent depression " are supplied by the marine 

 terraces of the Columbia and Fraser basin, and by the post- 

 tertiary beds of the California coast recently described by 

 Dall as rising gradually toward the south until at Monterey 

 and southward they are about six hundred feet above the 

 sea-level. . . The uplifting of the Wahsatch range 



is shown to be still in progress by post-Bonneville fault- 

 scraps." Mr. Gilbert's study of the horse-remains found in 

 the region would assign them to the period of "the upper- 

 most of the Lahontan and Bonneville beds," thus transferring 

 their geological horizon from the late tertiary to the latter 

 part of the glacial period. 



It is interesting to note, in connection with these old 

 lake-basins, that the Dead Sea in Palestine probably has a 

 similar relation to the development of glaciers in the Le- 

 banon Mountains, and Russell is of the opinion that the 

 gravel -deposits reported at various elevations about it are, 

 like those of Lakes Bonneville and Lahontan, records of 

 the Glacial period. t 



My own investigations upon the glacial deposits of the 

 Lebanon Mountains, however, showed that there had never 

 been any glaciers reaching the head-waters of the Jordan 

 Valley; but there was a glacier descending from the highest 



♦"Second Annual Report of the U. S. Geological Survey," p. 188. 

 t "Jordan-Arabah and the Dead Sea, "Geological Magazine/' 

 rol. 5, pp. 337, 387. 



