The general course of the creek was north-north-west: for the first ten miles it was without water, but its middle and upper course was well provided with fine reedy holes, the constant supply of water in which was indicated by Nymphaeas, and other aquatic plants. At its left side near the junction I observed, as before mentioned, a coarse grained sandstone, and, at less than a mile higher up, I found flint rock; and, wherever I examined afterwards, the rocks proved to be coarse grained granite and pegmatite, the decomposition of which formed a sandy soil on the slopes, and clayey flats along the creek. The latter, however, were very limited. The ant-hills were intimately connected with the rock, as the ants derived their materials for building from the minute particles of clay among the sand. The primitive rock was cut with deep gullies and ravines, and several tributary creeks joined Big Ant-hill Creek from the primitive side. The basaltic table land, which extended all along the right side of the creek, formed steep slopes into its valley, and were generally topped with loose basaltic boulders. The table land was highest near the creek, and its drainage was not towards the creek, but to the south-west, into the valley of lagoons. White quartz rock was observed in a few places on the right side of the creek, where the primitive rock seemed to encroach into the territory of the basalt; and felspathic porphyry formed probably a dyke in the pegmatite, but was most evidently broken by the basalt. Where the upper part of the creek formed a shallow watercourse, and turned altogether into the primitive formation, a plain came down from the west-north-west with a shallow watercourse, which continued the separation of the two formations; the right side of the plain being basaltic, the soil of the Box and Ironbark forest loamy, with sharp pieces of the rock; the left side being sandy, and covered with a very pleasing poplar gum forest, in which the grotesque ant-hills were exceedingly numerous. About two miles higher up the plain, separated into several distinct plains, the largest of which was from twelve to fifteen miles long, and from two to three miles broad, and came from Mount Lang; another plain came from an isolated razorback hill, and a third continued on the line of contact of the basaltic and primitive rocks. The upper parts of the small creeks, which come down in these plains, were full of water, and had their source generally between heaps of bare basaltic rocks, surrounded by rich grass, and a scanty scrub of Pittosporum, of the native mulberry, of the fig-tree, and of several vines, with Polypodiums, Osmundas, and Caladiums growing between them. Several other hills and mountains rose on the table land, generally with open plains at their base. The greater part, however, was open forest, principally of narrow-leaved Ironbark and Box, and occasionally poplar-gum.