THE IRRIGATION AGE. 115 



That the lake drained at one time into the Pacific Ocean long has 

 been a general belief, though geologists as a rule have insisted that 

 the opening did not exist when the surface was at its highest level. 

 They have asserted for the most part the conviction that the body of 

 water was as free from outlet then as now. and that the sinking of the 

 earth's crust to connect the lake with what are now the Snake and the 

 Columbia River was the first sign of decadence. A few have de- 

 murred and have pointed out that the lake was a fresh water body in 

 the prehistoric era, a state which would not have obtained long had 

 there been no rivers to drain its flow into the ocean. The issue is one 

 which apparently must ever go unsettled. 



At a rough estimate the first depression lowered the lake upwards 

 of 300 feet, assuming that the highest terrace was the highest lake 

 level, letting loose a torrent which must have torn its way through 

 mountains as if they were reeds, leaving plains where lofty peaks had 

 been, digging into the bowels of the earth, perhaps quenching for the 

 time being the subterranean fires which set it free until finally it 

 bored its path to the Pacific, fl,000 miles from the starting point of its 

 mad career. 



None may guess the interval between the first depression and the 

 second. The mountain handwriting tells of three separate falls, but 

 gives no limit of the time which elapsed before one followed the other. 

 After the third outpouring a different disturbance must have raised 

 the boundary walls and blocked the former outlets. Three gateways 

 may have been closed at once: there is no saying that the freed waters 

 followed identical routes to the ocean. Indeed, the contrary is more 

 within the range of probability. The volcanic theory fits nearly every 

 hypothesis. 



Within the present half century a radical change in area and coast 

 line has been accounted for on the basis that the internal disturbances 

 still continue, and that a part of the shore is as apt to sink downward 

 tomorrow as it was in the days before humanity had begun to keep 

 its record. 



The lake became salt after its final egress was cut off. Were out- 

 lets to be formed at this late period, it would remain salt for ages, so 

 deep has become the salt bed in the centuries since stagnation has 

 been the fate of the waters above. A few months ago a professor who 

 made a series of experiments, in the interest of the salt industry of 

 the lake, announced that if every other source of salt supply in the 

 world were cut off, the Great Salt Lake would be able to furnish the 

 ingredient as long as the world should endure. In that statement he 

 made no calculations for the possibility that the lake itself should 

 cease to exist, but even in that event, it is estimated that the solid de- 

 posits on its bottom would be sufficient to prevent salt hunger any- 

 where en the earth for as long a period as the mind can grasp. 



From these illustrations better than from figures one is able to 



