Page:A sketch of the physical structure of Australia.djvu/86

74 thickness exposed, and many of the points and headlands consisted of a pile of these large concretions of iron ore looking like a heap of slag's from an iron furnace. These concretions were black inside, but frequently red outside; when struck with a hammer they emitted a metallic sound, when broken open they seemed to be made up of small grains of quartz, with others of some mineral with a glittering metallic surface. They did not affect the magnet, but when tested by prussiate of potash and extract of galls, they appeared principally an ore of iron, while under the blowpipe it coloured a bead of borax a purple black, from which I conclude it is a compound of iron and manganese. I searched in vain for any organic remains in any of the rocks; but on visiting Port Phillip I was struck with the exact lithological resemblance in all these characters, which the tertiary rocks on the east side of that port bore to those of Port Essington. From this circumstance, from their perfect horizontality, from their little height above the sea, and from the incoherent and slightly consolidated state of these rocks of the north coast, I was induced to look upon them as likewise of tertiary age. I have, however, left the point doubtful in the accompanying map.

Captain King describes the cliffs about Anson Bay and Cape Ford and thence to Cape Dombey and Port Keats as of moderate height, level, made of dark red sandstone, or tenacious clay with ironstone