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California. The gradual disappearance of the Salton Sea by 
evaporation then began and is now in progress. Since 1907 the 
average annual rate of lowering of level by evaporation has been 
about 5 feet. 
The first three chapters deal with the geography, geology and soils 
of the Cahuilla basin, that written by the late Professor W. P. Blake 
being of special interest from the fact that it is based on observations 
begun with his discovery of the basin-like character of the region in 
1853 and extended to his last visit in 1906. Mr. G. Sykes deals 
in detail with the geographical changes recorded in the drainage 
system of the area. Mr. E. E. Free distinguishes two main types 
of soils—desert soils derived from the granitic rocks of the 
surrounding mountains and consisting mostly of unweathered 
angular fragments, and alluvial delta soils which are heavy and 
muddy silts or fine sands. The silty soils are alkaline owing to the 
accumulation in the surface-layers of excessive amounts of soluble 
salts, mainly chloride and sulphate of sodium, this accumulation 
being essentially a desert phenomenon due to the natural movement 
of water through the finer soils being too slight to remove the salts 
set free by decay of the soil minerals. Since in the sandy soils the 
capillary forces are too weak to allow reascent of rain-water to the 
surface, these soils are never alkaline unless the natural drainage is 
insufficient. Two interesting points are brought out in connexion 
with the alkalinity of the soils. The submergence of the soils by 
the Salton water seems to have had surprisingly little effect upon 
their alkali content, evidently because when the water retreats it 
does so slowly and the underground water-table lags considerably 
behind the actual water-line. In this way the soil after emergence 
remains long wet and has Salton water continually supplied to it by 
outward diffusion from the Sea and subsequent capillary rise. At 
the same time evaporation is intense and the Salton water brackish, 
and under these ideal conditions for the rapid accumulation of 
alkali, what alkali is leached out by the Sea will be restored, or 
more than restored, on its retreat. The second point is that the 
soils appear to have surprisingly slight influence on the distribution 
of vegetation ; it was found impossible to correlate the distribution 
of the beach vegetation with any variation of soil or soil-alkali. 
Mr. W. H. Ross reports on the chemical composition of the 
water of Salton Sea and its annual variation in concentration 
between 1906 and 1911. The annual increase in concentration has 
been fairly uniform during this period, and the proportion of total 
solids has now risen to a little over 1%. A table is given comparing 
the composition of the Salton Sea-water with that of other natural 
waters, and showing that the waters listed may be divided into four 
groups:—(1) chloride waters in which sodium chloride is the chief 
constituent, e.g., ocean water and that of Great Salt Lake; (2) 
chloride-sulphate watefs in which both chlorides and sulphates 
predominate, e.g., Caspian Sea; (3) chloride-sulphate-carbonate 
waters which contain notable amounts of carbonates as well as 
sulphates and chlorides, e.g., Salton Sea ; (4) natural salt-pans in 
which prolonged evaporation has brought about a concentration of 
the bromides and the soluble potassium and magnesium salts, while 
the less soluble sodium chloride and the carbonates and sulphates 
of calcium have mostly crystallised out, e.g., Dead Sea. 
