At nine miles we crossed some granite rocks, evidently a part of the ridge of Tarratta, thus exhibiting a uniformity in the granite with the general direction of other ridges, which is about north-north-east. The strike is between north and north-east; the dip in some places being to the west, and in others to the east, at great inclinations. The ridge of Kalingalungaguy consists of quartz, clay-slate, and the ferruginous sandstone, but I observed in the bed of the river a trap-dyke extending to the Bolloon ridge. Of the few low hills about the Lachlan it may be observed that they generally range in lines crossing the bed of that river. Mount Amyot is a ridge of this sort, being connected to the southward with Mount Stewart and Nyororong; and to the northward with the high ground separating the Bogan from the Goobang; the latter creek also forcing its way through the same chain on its course westward. Mounts Cunningham, Melville, and the small hills about them on each bank belong to another system of ridges of similar character, but more broken up; and the range of Kalingalungaguy with that of Bolloon form a third, also intersected by the river.
OF THE PLAINS IN GENERAL.
The plains appear to be divided into several stages by these cross ridges, which may have shut up the water of high floods in extensive lakes during the existence of which the deposits formed the surface of the present plains. Loose red sand also constantly forms low hills on the borders of these plains; and it seems to have been derived from the decomposition of the sandstone, and may be a diluvial or lacustrine deposit. Blue clay appears in the lowest parts of the basin, and forms the level parts of the plain, with concretions of marl in thin layers. This has every appearance of a mud deposit; but its depth is greater than the lowest part visible in the channel of the river. The parallel course of small tributaries joining rivers, which seem to be the middle drain of extensive plains, may have been marked out during the deposition of the sedimentary matter as tributaries, on entering the channel of greater streams, immediately become a portion of them; hence it is, the general inclination being common to both, that such tributaries do not cross these sediments of floods now termed plains in order to join the main channel or river now remaining.
CHARACTER OF THE GOOBANG AND BOGAN.
Thus the Goobang, on entering the valley of the Lachlan, pursues a parallel course until the ridge from Hurd's peak confines the plain on the west and turns the Goobang into the main channel. The Bogan, on the opposite side of the high land, may be said to belong to the basin of the Macquarie, although it never joins that river, but merely skirts the plains which, below Cambelego, may be all supposed to belong to the original bed of the Macquarie. Throughout its whole course of 250 miles the left bank of the Bogan is close to low hills, while the right adjoins the plains of the Macquarie. The basin of the Macquarie, as shown by its course near Mount Harris and Morrisset's ponds, falls northward, but that of the Darling to the south-west. It is not at all surprising therefore that the course of a tributary so much opposed, as the Macquarie is, to that of the main stream, should spread into marshes: still less that, on being at length choked with the deposit filling up these marshes, it should work out for itself a channel less opposed to the course of the main stream. Duck creek appears to be now the channel by which the floods of the Macquarie join the Darling, and in a course much more direct than that through the marshes. Hence the Bogan also, being still less opposed to that of the Darling, finally enters that river without presenting the anomaly of an invisible channel. In like manner, at a much lower point on the Darling, the course of the little stream named Shamrock ponds, so remarkable in this respect, may be understood. This forms a chain of ponds, or a flowing stream, according to the seasons, between the plains on the left bank of the Darling, and the rising grounds further to the eastward: but instead of crossing the plains to join the main channel this supposed tributary, after approaching within one or two miles of the Darling where its plains were narrow, again receded from it as they widened, and finally disappeared to the left where the plains were broad, so that its junction with the Darling has not even yet been discovered. On this principle the channel of the Lachlan, as soon as it enters the plains belonging to the basin of the Murrumbidgee, may be sought for on the northern skirts of these plains, although its floods may have been found to spread in different channels more directly towards the main stream.
At 12 1/4 miles we crossed a dry and shallow branch of the river, and at 14 1/2 miles we at length reached the main channel, and encamped where a considerable pond of water remained in it, surrounded by abundance of good grass. In this hole we caught some cod-perch (Gristes peelii).
April 12.
I sent back three men with two horses to bring on the light cart of Mr. Stapylton, intending to await its arrival (which I expected would be in five days) at the end of this day's journey. It was my object to encamp as near as possible to Regent's Lake without diverging from the route which I wished to follow with the carts, along the bank of the Lachlan.
WANT OF WATER IN THE RIVER.
For this purpose it was desirable to gain a bend of that river at least as far west as the most western portion of the lake, according to Mr. Oxley's survey. This distance we accomplished and more; for we were obliged to proceed several miles further than I intended, and along the bank of the river, because no water remained in its bed, until Mr. Stapylton found a good pond where we encamped after a journey of 16 1/4 miles. Notwithstanding such an alarming want of water in the river, we saw during this day's journey abundance in hollows on the surface of the plains; a circumstance clearly evincing that this river, as Mr. Oxley has truly stated, is not at all dependent for its supply on the rains falling here. The deep cracks on the plains, so abundant as to impede the traveller, seemed capable of absorbing not only the water which falls upon them, but also any which may descend from the low hills around. During our day's journey I found grey porphyry, the base consisting apparently of granular felspar with embedded crystals of common felspar and grains of hornblende.