para.] which had evidently been washed to pieces by the violent action of
water, and which appeared to have been originally, of nearly the same
general elevation as the table lands to the westward. It seems to me,
that these table lands have formerly been the bed of the ocean, and this
opinion is fully borne out by the many marine remains, fossil shells, and
banks of oyster shells, [Note 35 at end of para.] which are frequently to
be met with embedded in them. What are now the ranges of the continent
would therefore formerly have been but rocks or islands, and if this
supposition be true, there are still hopes that some other islands are
scattered over the immense space occupied by Australia, and which may be
of as rich and fertile a character, as any that are yet known. Thus if
the intervening extent of desert lying between any of the known portions
of Australia, and what may be considered as having been the next island,
can be ascertained and crossed over, new and valuable regions may yet be
offered for the extension of the pastoral interest of our Colonies,
and for the general spread of civilization and improvement.

[Note 34: "An hundred miles above this, I passed a curious feature, called
the "Square Hills" (plate 123 ). I landed my canoe and went ashore, and to
their tops to examine them. Though they appeared to be near the river, I
found it half a day's journey to travel to and from them; they being
several miles from the river. On ascending them I found them to be two or
three hundred feet high, and rising on their sides at an angle of 45 deg.
and on their tops, in some places for half a mile in length perfectly
level, with a green turf, and corresponding exactly with the tabular
hills spoken of above the Mandans, in plate 39, vol. 1. I therein said
that I should visit these hills on my way down the river; and I am fully
convinced from close examination, that they are a part of the same
original superstratum, which I therein described, though 7 or 800 miles
separated from them. They agree exactly in character, and also in the