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22 dominate, the process of evaporation, by which only the surface waters are diminished, there being no known outfall for them, not only leaves in deposition any saline matters that may be present in them, but also may cause the formation of crystals of gypsum, as Mr. Brown supposes, and consequently the lakes so formed are salt; while those of which the clay basins are formed by the disintegration of granitic or erupted rocks are fresh, as are the springs commonly found at the bases of elevations of those rocks.

A considerable portion of this district is, after rains, richly grassed, and has been utilized for grazing sheep and cattle; but as rain falls at very irregular periods, and often at long intervals, it is therefore unfit for agricultural purposes. Long belts of a thick but low growth of small Eucalypti are found traversing it at intervals. It may probably be found hereafter rich in those minerals which accompany or are contained in granitic transition or erupted rocks.

The Lake district may be considered as a shallow basin on a plateau of 300 miles square, and is buttressed up on three sides by elevations which form the watersheds of the rivers, the valleys of which open to the coasts of the Colony. The superior ranges, which separate the river basins, commonly present bare surfaces of granitoid rock; the inferior are, for the most part, covered with a concretionary rock, frequently appearing as a conglomerate, known in the Colony as iron-stone, which is also common in the valleys and on the flanks of the ranges on the West Coast, while to the North and South sandstones predominate. As is commonly the case, the highest points project in front of the main mass, but it is not probable that any attain to 2000 feet above the level of the sea, and the greatest elevations