984 SCIENTIFIC EXCURSIONS IN NEW HOLLAND. 
The channels are, however, very broad and full of rolled 
pebbles; indeed, two separate channels may be often seen; 
the inner one, where there is yet some water, and which is 
fringed by a thick serub on each side of Casuarina (Swamp 
oak); and the other filled with sand and rolled stones, and 
here and there a stout Gum tree, which has succeeded in 
braving the force of a stormy deluge, or of many weeks 
incessant rain. 
Between the Peel and the Wamoy rivers, the forest vegeta- 
tion changes; and instead of travelling under Spotted Gums, 
Box, and narrow leaved Iron Bark, there is only seen a dense 
growth of Silver-leaved Bark, with its grey green foliage. 
A range of trachytic mountains separates the Wamoy and 
Gwydir, near the sources of the Rocky Creeks, which is a 
stream tributary to the Gwydir. I examined these moun- 
tains as closely as my limited and rude instruments and 
means of investigation would permit. 
Westward of these mountains may be seen the Big River, 
pursuing its course to join the Wamoy, which, lower down, 
is called the Bavan and still nearer to its mouth, the Darling. 
This and several other streams take their rise in the high 
table land of New England; and they all unite near the 
Darling, passing alike amid mountains of granite, basalt, 
and quartz, and being full of water in their upper part; but 
invariably dwindling, after they leave the mountainous 
region, till, on approaching the western plains, their dry 
beds contain little else than sand, except in-the season 
the heavy periodical rains. 
It is most interesting to see how the showers, which fall 
on the table-land of New England, not twenty English miles 
of the eastern coast, take a course of one thousand miles, 0 
water the country and to issue finally into the southern 
ocean. The land, lying between the Severn and Condamine 
rivers, is a plain, called by the colonists, Bricklow Scrub, 
the Bricklow being an Acacia, with long and stiff greyish 
phyllodia, which often grows associated with Forest Oak, à 
Casuarina and many sorts of brushwood, Iron Bark, and 9 
