24th January.
At 6.0 a.m. crossed the creek, and steered south-east over broken
sandstone ridges till 8.0, when we entered a plain of basaltic formation
covered with good grass, and where the ground was not entirely composed
of fragments of rock the soil was a rich black loam; crossing the large
creeks trending north, at 10.0 a.m. halted on the second. These creeks
appear to rise in a steep range of sandstone hills which bound the
basaltic plains to the west, about two miles from our track. At 3.0 p.m.
resumed our route and traversed the trap plain for one and a half hours,
and bivouacked in a small gully; the country on both sides of our track
seems to be of trap formation for several miles, and then rises into
sandstone hills with flat tops. The basaltic rock of this plain is not of
great thickness, as the sandstone rose in a few spots above its surface
and formed small islands covered with coarse vegetation, surrounded by
the open grassy plain. The basalt seems to have been poured out into the
valley after it had been excavated in the sandstone, and not to have been
much disturbed subsequently. The surface of the plain is very stony, and
the horses' feet were much injured by the roughness of the rock.