EXAMINATION OF WATERS OF GREAT SALT LAKE. 243 



It will be observed that the foregoing accords iu general with the 

 history of the oscillations of the lake, a low density being coincident 

 with a period of high water, and conversely. For a variety of reasons, 

 ])riucipally because of the nonconformity in the location and other 

 conditions of the collection of samples, there is not an absolute agree- 

 ment. 



The density of the lake varies in its different parts, being lowest close 

 to the mouths of the rivers and highest near dry shelving shores. In 

 the latter case the density is raised by evaporation in the shallow water 

 until it sometimes reaches the saturation point and the salt is crystal- 

 lized out and precipitated on the bottom. The process is aided, of 

 course, by tlie fact that the lake has no appreciable semidiurnal tides, 

 which would tend to produce a more equable distribution of its saline 

 contents. The circulation, however, in the deeper waters removed from 

 the river mouths is probably sufficient to make the density uniform 

 over large areas. 



Near the mouths of the rivers the density is largely conditioned by 

 the volume of fresh water brought down by the stream. When the 

 discharge is heavy the dense water of the lake is pushed back and 

 the zone at which the mingling of the fresh and salt waters occurs is 

 farther from shore than when the discharge is light. If the rivers 

 maintained an approximately even flow during the year this fact could 

 not materially affect the feasibility of introducing marine animals, such 

 as the oyster, for the zone of admixture would remain, other things 

 being constant, at approximately the same position. It happens, how- 

 ever, that the rivers discharging into Great Salt Lake pass through 

 annual oscillations of great magnitude, the maximum and minimum How 

 of Bear River in 1897, according to the figures published by Professor 

 Fortier, and previously quoted, being about as 15 to 2, and of Weber 

 Kiver iu the proportion of about 28 to 1. Data for the Jordan Eiver 

 are not available. It will be seen, therefore, that the fluctuations in 

 the position of what we may call the neutral zone, in which the water 

 has a density of between 1.01 and 1.02, must be very great. Again, 

 during nonperiodic stages of high water — as, for instance, that culmin- 

 ating in 1869 — the salt water encroaches on the fresh, and some of the 

 former fresh-water channels of the rivers become converted into more 

 or less saline estuaries. 



The annual oscillations would probably affect the local density to a 

 smaller degree, partly because the influence of the higher level of the 

 lake would be masked by the greater inflow of fresh water, as it occurs 

 synchronously, not with the maximum, but still with a high stage of 

 water in the river, and partly by reason of the fact that the rise is not 

 so great as in the nonperiodic oscillations. 



Another factor which tends to produce variations in the salinity are 

 the irregular changes in the lake's level, due to the action of the wind. 

 As before stated, winds of even moderate intensity tend to back uj) 

 the water on flat lee shores, with the result that the denser water 



