At 7.15 a.m. again steered east up the river, the country level and timbered with stringybark, box, bloodwood, leguminous ironbark, and rusty gum; the soil a red sandy loam, thinly grassed; at 10.30 a.m. came to low hills and ridges of granite and porphyry, timbered with box, leguminous ironbark, terminalia, and the grass somewhat improved. Altered the course at 11.0 a.m. to the south to close in with the river; but after crossing a great number of dry watercourses, and even steering west, only reached the bank of the river at sunset. The channel was dry, and all the vegetation had disappeared, only a barren waste of coarse sand and gravel 180 yards wide, with bare rocky banks, showed that it had once been a running stream. A few small hollows in the rocks retained water from the late rain, but not sufficient for our horses, and though we found a small pool in the sand, it was insufficient for the supply of the party. Encamped at 6.0 p.m. The geological structure of this portion of the country is wholly dissimilar to any other part of North Australia we have yet traversed. Granite, porphyry, and slate are the prevailing rocks. The whole appear to have been subjected to considerable disturbance, as the slate is much broken and contorted, and in several parts altered by contact with the porphyry, and no definite strike or dip appeared to exist. The porphyry is of a red-brown colour, consisting of grey paste with crystal of felspar and angular fragments of slate and granite sometimes one foot in length. The granite contains little mica, and the quartz frequently is arranged in rhomboidal crystals nearly parallel to each other; it readily decomposes, and from the predominance of quartz forms a coarse gritty soil. Quartz-rock forms large beds and veins in the granite, and has a general trend north and south. It often contains crystals of mica, and therefore not likely to contain metals. In washing the sand of the river near Camp 83, only a small quantity of titaniferous iron remained after the removal of the quartz and mica. It was in this locality that the Gilbert Gold Field was afterwards discovered. Latitude by e Pegasi 18 degrees 25 minutes 33 seconds. 30th September.