GREAT SALT LAKE. 437 



points of resemblance to Salt Lake. It is situated at 4,000 feet above sea- 

 level, is 80 miles long, and 30 miles in average width. Its shores are very 

 flat, and it is subject to annual variations of level of 3 to 6 feet. ItiS supply 

 of salt is supposed by Edw. Hitchcock to be derived from Triassic sand- 

 stones, as there are salt streams flowing into it from them. Salt Lake, on 

 the other hand, is not connected, so far as known, with any salt deposits 

 by its tributary streams, which have no perceptible salt taste. Deposits of 

 salt are known to exist, however, in rocks of the Jurassic age, which may 

 have been connected with Lake Bonneville. 



The Dead Sea of Palestine is 60 miles long by 15 miles wide, and has 

 an extreme depth of 1,800 feet, while its surface is over 1,300 feet below 

 the level of the Mediterranean Sea. The depression occupied by the Dead 

 Sea and the Lake of Tiberias is supposed to have been once occupied by 

 the Mediterranean, and, having been cut off, to have reached its present con- 

 centration of salts by evaporation. In this respect, it resembles Salt Lake, 

 which is the concentration of Lake Bonneville. It is also subject to changes 

 of leviel of 15 feet, and has extensive deposits of mineral salts on its borders, 

 like those of the Grreat Desert. The water of Salt Lake differs from it 

 principally in its smaller proportion of magnesia and lime. 



In its relative proportion of soda and magnesia, it resembles more 

 closely the composition of ocean salt than that of either of these two lakes. 



The two shore-lines on the east and west sides of Salt Lake present 

 the greatest contrast in appearance. On the west, the shallow waters of the 

 lake merge almost imperceptibly into the flat plains of the Great Desert, 

 which will be described in a later section. On the east, green meadows, 

 intersected by mountain-brooks, stretch up to the foot of the rugged slopes 

 of the Wahsatch. From Ogden Point south to Salt Lake City, the immediate 

 shores of the lake are occupied by varying widths of low marsh-land, which 

 are continually being encroached upon by the rising waters of the lake. 

 Along the flanks of the mountains are comparatively steep slopes of Quater- 

 nary gravel and soil, which sometimes extend out in terrace-like ridges, 

 composed, as far as can be seen, of loosely agglomerated sandstones and 

 gravel conglomerates. These are principally developed near Ogden City 

 and to the south and west of the mouth of the Weber Canon, and represent 

 a formation, probably of Pliocene age, which once occupied the valley. 



