Page:A sketch of the physical structure of Australia.djvu/51

39 In the cliffs of Port Phillip, on the west of Geelong, is seen about 40 feet of brown and yellow sand, with layers of soft sandstone, containing no fossils. On the east of the town, cliffs from 24 to 50 feet high, extend for about a mile, in which at half a mile distant are seen beds of a white concretionary limestone, sometimes tufaceous, and often a regular travertine. The bedding was at first irregular, but it passes towards the east into a smooth compact cherty limestone, with regular beds dipping W.S.W. at 5&deg;. These beds contained small shells of the genera helix and planorbis, and the limestone was like a fresh-water limestone. It is not known anywhere except in these headlands, between Geelong and Corio. This limestone is therefore the monument of some old fresh water lake that must have existed formerly in this tract, when the physical geography of the neighbourhood must have differed considerably from its present state. The town of Geelong itself, stands on the lava, and the ridge between the port and the river Barwon, as well as the bed of that river, for about one mile above, and two miles below South Geelong, seems to consist entirely of the same rock.

Both in the neighbourhood of Geelong and Melbourne, recent shells may be seen, either scattered over the ground, mixed with the soil, or accumulated in ridges showing a comparatively recent elevation of the land. These sea shells are believed by the colonists to have been brought and left by the natives, and small heaps that have been so brought may be seen often enough. The shells I mean, however, are all considerably and equally decomposed, shewing that they were deposited at the same time or nearly so, and that that time was an ancient one. Besides which, they exist in numbers greater than could have been brought by the natives, unless the whole population of Australia had been employed in carrying them for centuries.

I now proceed to lay before the reader what has been described by others of the structure of the Port Phillip district, or the country south of the