of rounded undulations of sand or pebbles washed perfectly smooth and even, looking like waves of the sea, and seeming as if they had not been very many centuries deserted by the element that had moulded them into their present form.  In this singular district I found scattered at intervals throughout the whole area inclosed by, but south of, Lake Torrens, many steep-sided fragments of a table land, [Note 34 at end of 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 materials of which they are composed; and I believe that some unaccountable gorge of waters has swept away the intervening earth, leaving these solitary and isolated, though incontrovertible evidences, that the summit level of all this great valley, has at one time been where the level surface of these hills now is, two or three hundred feet above what is now denominated the summit level.”—­Catlin’s American Indians, Vol. 2. pp. 11 and 12.]

[Note 35:  Similar banks of fossil shells and oyster beds, are found in the Arkansas.—­Vide Catlin, Vol. 2. p. 85.  At page 86, Mr. Catlin describes banks of gypsum and salt, extending through a considerable extent of country, and which apparently was of a very similar formation to some of the localities I was in to the north of Spencer’s Gulf.]