r above the sea.

SALT LAKES IN THE INTERIOR.

The hills on the margins of the Australian salt lakes are always on the
north-east side, or opposite that of the prevailing south-west winds. The
formation of these hills is probably due to the action of the wind, the
growth and decomposition of small shells, the carbonate of lime
disengaged by evaporation, and the concretion of calcareous matter and
friable tuff so common in these ridges.

In two of the most remarkable, Mitre Lake and Greenhill Lake, a portion
of the basin of each, between the hilly curves and the water, was filled
by a dark-coloured perfectly level deposit, apparently of vegetable
mould. This being of a quality different from that of the hills, it would
appear that any process by which these heights may have originated
through the agency of the water adjacent and the wind could not continue
after this different formation had accumulated between them. Accordingly
where this dark-coloured deposit is most extensive the curved hill
concentric with the outer margin seems less perfect; but whether worn by
time or sweeping inundations I cannot pretend to say.

That some affinity exists between such accumulations and the salt water
in the lakes is the more probable from the present state of those of
Cockajemmy, which occur in the bed of a former current, and between the
rocky sides of a kind of ravine. Even in such a situation a mound of very
firm ground has been formed on the eastern bank of each, and was found
very convenient for the passage of the ravine by the carts of the party.
(See above.)

In those hills beside salt lakes on the plains a tendency to regular
curvature was the chief feature: the relative situation with respect to
the water and the wind was always the same; while in some cases, where
grassy flats had once been lakes, crescent-shaped green mounds were still
apparent on the north-eastern sides of each. If these remains of salt
water are of less volume than they have been formerly, as may be presumed
from these circumstances; and if the waters according to Professor
Faraday's analysis "are solutions of common salt and, except in strength,
very much resemble those of the ocean,"* we cannot have much difficulty
in believing that the sea deposited the water in these situations at no
very remote period.

As a dark-coloured soil is also found in the ridges about some of these
lakes we must look deeper for the original cause of such depressions