Page:A sketch of the physical structure of Australia.djvu/50

38 The general structure of the country around Geelong, is the same as that around Melbourne, an old formation believed to be palæozoic, a modern tertiary one, and rocks certainly igneous and apparently volcanic. The Barraboul hills, a few miles N.W. of Geelong, consist of a light olive brown or greenish sandstone, sometimes micaceous, sometimes grey and hard internally, at others a good freestone, very thick bedded, occasionally containing a line or two of small quartz pebbles. Reed-like vegetable impressions like coal plants were seen in it, and on the N.W. side coal one or two inches thick, was said to have been passed through in sinking a well. It dips in various directions between south and east on the Geelong side of the hills, at angles varying from 12&deg; to 25&deg;. It is traversed by one or two considerable faults perceptible in some of the cliffs; and at one place grey grit and indurated shale were seen beneath the sandstone. These I believed to be palæozoic rocks. Between the Barraboul hills and Geelong, there were some flats and gently rising grounds occupied entirely by the rough scoriaceous lava or trap, (locally called ironstone). There were likewise some gentle hills of tertiary rocks. At one place these were exposed in an excavation for a lime kiln, and they were found there to be a coarse yellow rubbly limestone, very like some of the oolitic limestones of the Cotteswold hills, full of fossil shells, principally pectens, but others of the same species as those in the tertiary sandstone, near Melbourne; there were also the same spatangi. This coarse limestone was not burnt in the kiln, but a white earthy very pure limestone, which was found as a shell or coating over the whole hill, not more than 6 inches in thickness, and immediately beneath the vegetable soil.