GREAT SALT LAKE. 431 



SECTION VI. 



LAKE REGION. 



BY S. F. EMMONS. 



Great Salt Lake. — The Great Salt Lake of Utah is a broad, shallow- 

 sheet of water, occupying the lowest portion of the Utah Basin, 80 miles in 

 length in its greatest extension in a northwest and southeast direction, and 

 about 32 miles wide at its greatest average lateral expansion. Its bottom 

 is evidently even more level than the broad desert- valleys wdiich surround 

 it, since at its deepest points its waters do not reach a depth of 50 feet, while 

 a very large proportion of its area, comprising broad belts along the shore- 

 line and the partly-enclosed bays, have less than 10 feet of water. The 

 line of deepest depression is that extending northwest from Black Rock 

 Point, between Stansbury and Antelope Islands, and to the west of the 

 Promontory Mountains. This valley averages about 40 feet in depth below 

 the present surface of the lake, while in no other portion of the lake, except 

 in the immediate vicinity of Fremont's Island, are depressions of more than 

 20 feet found. It receives its supply of fresh water from four large streams, 

 the Bear, Ogden, Weber, and Jordan Rivers, which, with a few minor 

 mountain-streams from the western slopes, bring down the drainage of all 

 the surface of the Wahsatch Range and the eastern portion of the Uinta 

 Range, while a small but continuous supply of salt is furnished by the 

 numerous springs which occur along its shores. 



As it has no outlet, this great influx of fresh water would rapidly 

 raise the level of the lake were it not for the enormous evaporation that 

 takes place in this dry region, where the average difference in summer 

 between the wet- and dry-bulb thermometers is from 20° to 30° (Fahren- 

 heit). The level of the waters of the lake is, therefore, subject to changes 

 depending on oscillations in climate and variations in the condensing power 

 of the atmosphere from year to year. It might naturally be expected that 

 there would also be some variation in the level of the lake at different sea- 

 sons of the year, but it is probably slight, and no data have been obtained 



