In support of the first of these conclusions, it would appear that a current of water must have swept the vast accumulation of shells, forming the great fossil bank through which the Murray passes from the northern extremity of the continent, to deposit them where they are; and it would further appear from the gradual rise of this bed, on an inclined plain from N.N.E. to S.S.W., that it must in the first instance, have swept along the base of the ranges, but ultimately turned into the above direction by the convexity of the mountains at the S.E. angle of the coast.  From the circumstance, moreover, of the summit of the fossil formation being in places covered with oyster shells, the fact of the whole mass having been under water is indisputable, and leads us naturally to the conclusion that the depressed interior beyond it must have been under water at the same time.

It was proved by barometrical admeasurement, that the cataract of the Macquarie was 680 feet above the level of the sea, and, in like manner, it was found that the depot of Mr. Oxley, on the Lachlan, was only 500, there being a still greater fall of country beyond these two points.  The maximum height of the fossil bank was 300 feet; and if we suppose a line to be drawn from its top to the eastward, that line would pass over the marshes of the two rivers, and would cut them at a point below which they both gradually diminish.  Hence I am brought to conclude that in former times the sea washed the western base of the dividing ranges, at or near the two points whose respective elevations I have given; and that when the mass of land now lying waste and unproductive, became exposed, the rivers, which until then had pursued a regular course to the ocean, having no channel beyond their original termination, overflowed the almost level country into which they now fall; or, filling some extensive concavity, have contributed, by successive depositions, to the formation of those marshes of which so much has been said.  I regret extremely, that my defective vision prevents me giving a slight sketch to elucidate whet I fear I have, in words, perhaps, failed in making sufficiently intelligible.

Geological remarks.

Now, as we know not by what means the changes that have taken place on the earth’s surface have been effected, and can only reason on them from analogy, it is to be feared we shall never arrive at any clear demonstration of the truth of our surmises with regard to geographical changes, whether extensive or local, since the causes which produced them will necessarily have ceased to operate.  We cannot refer to the dates when they took place, as we may do in regard to the eruptions of a volcano, or the appearance or disappearance of an island.  Such events are of minor importance.  Those mighty changes to which I would be understood to allude, can hardly be laid to the account of chemical agency.  We can easily comprehend how subterranean fires will occasionally