Our first encampment was on the banks of a small river at a spot 2,640 feet from the sea.  This river ran through a deep and narrow valley, descending with a nearly regular slope from a tableland of sandstone, in which it took its rise about seven miles inland.  At this encampment the height of the bed of the river above the level of the sea was 188.76 feet, as found by the mean of several very accordant observations, which, at the same average slope, gives an elevation of about 377 feet for the height of a spot on its banks distant only one mile from the sea; and if we conceive the average increase of elevation to the sandstone tableland to be only 200 feet in every mile (and I believe it to have been more) we shall have 1400 feet for the elevation of the tableland which formed one of the highest parts of Macdonald’s Range.

ELEVATION OF HILLS.

After passing across this range we again descended rapidly into the low country, the face of which is much broken by conical hills composed of basalt.  The heights of some of these hills above their base, which had a considerable elevation above the sea level, were in three instances as follows: 

February 28.

The measured height of a hill above its base was 331 feet.

March 4.

Measured the altitude of a hill above its base and found it to be 222 feet.

March 8.

Measured the altitude of a hill above its base and found it to be 229.5 feet.

None of these hills had apparently near so great an elevation as the sandstone range of which they were under-features.  At this period our barometer was unfortunately broken.  We now proceeded up the banks of the Glenelg and arrived at many hills and conical peaks, apparently much higher than those I had measured; yet on afterwards passing the river and attaining the summit of the opposite sandstone range, we looked down upon them as hills of far inferior elevation to those on which we stood.  From this circumstance, and from the very perceptible change of temperature we experienced, I should think the altitude of the farthest point of Stephen’s Range which we reached must have been 2,500 or 3,000 feet above the sea.

CHARACTER OF THE RIVERS.

The rivers in North-western Australia much resemble in character those of the south-eastern parts of the continent.  They rise at no very great distance from the sea.  Near their sources they are mountain torrents, but in the lowlands they become generally streams with slow currents, winding through fertile and extensive valleys or plains which are liable to sudden and terrific inundations, caused, I conceive, by the rain which falls in that part of the mountains where the rivers take their rise; for at one period, when we had our encampment on the bank of the small stream near the sea at Hanover Bay, I was myself distant about fourteen miles in the interior in the direction of its source, where we had heavy rain; and on my return I found that the party at the station had been surprised by a sudden rising of the water for which there was no apparent cause as there had been no rain where they were.