Observation 1. Such is the character of the country where the waters separate, or in the line of greatest elevation which we are accustomed to term the Coast Range. The general direction of this range is north-north-east and accords perfectly with the hypothesis of Dr. Fitton, founded on the general parallelism observed in the range of the strata, even on the north-western coast, as noticed in his interesting little volume, the first ever devoted to Australian Geology.* The parallelism so remarkable in the range of strata in that portion, the general tendency of the coastlines to a course from the west of south to the east of north on the mainland, and even in the islands west of the Gulf of Carpentaria, and a general elevation of the strata towards the south-east, as deduced from Flinders' remarks, are all facts which should be studied in connection with the direction of the granite along this part of the eastern coast.
(*Footnote. An account of some Geological specimens from the coasts of Australia by William Henry Fitton, M.D., F.R.S., V.P.G.S., etc. 1826.)
Observation 2. It may be also observed that the sandstone reposing on the rock eastward of this division or watershed is slightly inclined towards the sea, whereas all the sandstone on the interior side, or westward of it, dips to the north-west.
TRAP-ROCKS.
Trap-rocks are displayed in a great variety of situations. They often occur connected with limestone in valleys, sometimes constitute lofty ranges as on the north or left bank of the Hunter, and along the seashore at the Illawarra; they likewise cap the summit of isolated hills, but no particular place can be assigned to them with reference to the position of any other rocks. Trap forms a good soil on decomposition as is shown in the rich districts of the Illawarra, Cowpastures, Valley of the Hunter, Liverpool Plains, Wellington Valley, and Buree.
Vesicular lava and amygdaloid are the chief ingredients of some of the best parts of Australia Felix. In that region volcanic phenomena are more apparent than in other parts of Eastern Australia, especially where the Grampians, consisting of a mass of sandstone 4000 feet thick, seem a portion of the great formation covering the districts of the north. The strata in these mountains are inclined to the north-west, as if in obedience to the upheavings of Murroa or Mount Napier, an extinct volcano in the very line of their outcrop.
Observation. We found in the interior, hills of sandstone only, but at this extremity of the great Coast range granite is extensively exposed in ridges, between which, in one extensive district, are round heights of mammeloid form, consisting of pure lava, and in another, tabular masses of trap reposing on granite occupy one side of a valley.
GRAVEL.
Beds of gravel are not common in these parts of Australia; but occur partially in the basins of the larger streams on the interior side of the Coast range where the pebbles in general consist of quartz.
SANDSTONE.