THE OVERLAND ROUTE OGDEN TO SAN FRANCISCO. 



153 



quarry faces expose the thick beds of dark-bhie Paleozoic liniestone. 

 To the north Strong Knob^ which at the present hike level is almost 

 an island, presents a bluff front of conspicuous white and black rock. 

 Salt marsh lands on both sides of the track are sometimes flooded, 

 sometimes covered with a crust of glistening white salt/ stretchh 

 away to the south as far as the eye can see. A mirage can nearly 

 always be seen on these plains, the distant mountains to the south 

 appearhig to be surrounded by water, the ghost of the greater Lake 

 Bonneville. (See pp. 97-99.) This area is a part of the Great Suit 



in 



general level of the lake would' reflood the whole area. 



A water tank and section house at milepost 730 are at the end of 

 a 52-mile pipe line. Drilling for fresh water on the west side of 



Great Salt Lake has not been successful. All 



stretches, 

 :ic grains, 



mix 



not so uniform or so clean as those in the dunes at Lakeside. 



Brown fly larvae and their cast-off shells pile up along the railroad 

 embankment Avhcn the water is high, often creating an offensive odor. 

 Sometimes they collect in such masses over the rails that they make 

 the tracks slippery, actuafly interfering with the passage of trains. 

 Olney, a siding and signboard only, is situated in the midst of a 

 bare salt-incrusted desert. Beyond it the railroad rises slightly 



over low gravel ridges, some of which show distinct 



of former 



Olney. 



Elevation 4,2n feet. 

 Omaha 1,057 miles. 



beach terraces and gravel bars, 



marks 



higher lake levels. A few isolated outcrops of dark 

 limestone project through the valley deposits. The 

 railroad descends slightly to the level of the Great Salt Lake Desert 



^ The white incrustation seen for a long 

 distance wert of Great Salt Lake con- 

 sists of chemical compounds or salts that 

 are more or less soluble in water, all of 

 which are popularly included in the term 

 "alkali-" In its strict sense that term 

 refers only to a certain group of chemical 

 compounds that have the power of neu- 

 tralizing acids and have a corrosive action 

 on animal and vegetable tissue. The 

 most powerful of these are the lyes, the 

 hydrates of sodium and potassium. The 



less commonly borax. More rarely in 

 this part of the country the soluble cal- 



cium ox 



masrnesium 



salts are found. 

 However, where the soluble (sodium and 

 potassium) carbonates occur the salts in 

 fact partake of the character of true alkali. 

 The carbonates of sodium and potassium, 

 being formed by the combination of a 

 sti'ong base (sodium or potassium) and a 

 weak acid (carbonic), break up (hydrolyze) 

 to a certain extent in solutions, and thug 

 there is actuallv liberated a small amount 



salts which incnist the desert surface are 1 of free caustic alkali. The wat-er-soluble 



not ordinarilv of this character at all. 

 For the most part they consist^ chiefly, 

 in places almost exclusively, of common 

 salt (sodium chloride). In many places, 

 however, they include also other readily 

 soluble salts— Glauber's salt (sodium sul- 

 phate), washing soda (sodium carbonate), 

 bakinj> soda (sodium bicarbonate), and 



carbonate of soda, known on account of 

 its darkening effect in soils as *'black 

 alkali," is very destructive of vegetation. 

 The less harmful '* white alkali" consists 

 of a mixture of the neutral soluble ealta, 

 in large part common salt, and its pres- 

 ence, as the name implies, is indicated 

 by a white incmstatiori. 



