Old Red Sandstone.—Composition of D'Urban's group. The highest elevation ascended during the expedition, being nearly 600 feet above the level of the plain in which it rises. It lies to the S.S.W. of Oxley's Table Land, distant 40 miles, and the rock of which it is composed is much harder and closer.
Breccia.—Colour pale yellow, silicious cement. Composition of some trifling elevations to the North of New-Year's range, with which it is doubtful whether they are connected.
Chrystallized Sulphate of Lime.—Found imbedded in the alluvial soil forming the banks of the Darling river. Occurring in a regular vein. Soft, yielding to the nail; not acted on by acids.—See Plate.
Breccia.—Pale ochre colour, silicious cement, extremely hard. Cellular, and sharp edges to the fractured pebbles. Has apparently undergone fusion. Occurs in the bed of the Darling in one place only.
Sandstone Varieties.—Colour dull red and muddy white; appears like burnt bricks; light, easily frangible; adheres to the tongue; occurs in large masses in the bed of the Darling;
probably in connection with the rock-salt of the neighbourhood, which, from the number of brine springs discovered feeding the river, must necessarily exist.
Variety of the same description of rock.
Jasper and Quartz.—Showing itself above the surface of a plain, from which D'Urban's group bore S. 40 E. distant 33 miles.
It is a remarkable fact, that not a pebble or a stone was picked up during the progress of the expedition, on any one of the plains; and that after it again left Mount Harris for the Castlereagh, the only rock-formation discovered was a small Freestone tract near the Darling river. There was not a pebble of any kind either in the bed of the Castlereagh, or in the creeks falling into it.