I was very ill at starting, and remained so for some days after, but as I had already been twice over the ground, and as my native boy was able to act as guide to the party, my indisposition was not of so much consequence as it would have been under other circumstances.  At times I was quite incapable of any exertion, and could not attend to any thing, being hardly able to sit upon my horse for half an hour together.  From the 25th to the evening of the 30th, we were engaged in travelling from Mount Arden to Depot Pool, by the same line of route by which myself and the native boy had returned from our exploration.  In our progress we noticed many traces of natives around us, and saw many native fires among the hills; the people themselves did not, however, appear.

By a little trouble in examining the watercourses before encamping, we were generally able to procure water for our horses, at some distance among the hills; and we were usually fortunate enough to obtain tolerable food for them also.  The grass, it is true, was generally scanty, or dry; but we found a succulent plant of the geranium tribe, bearing a small blue flower, and growing where the channels of the watercourses spread out in the plains, in the greatest abundance, and in the wildest luxuriance; of this the horses were extremely fond, and it appeared to keep them in good condition and spirits.

July 30.—­The geological formation of the country we had passed through, consisted in the higher ranges of an argillaceous rock, of quartz, or of ironstone.  Upon some of the hills the small loose stones had a vitrified appearance—­in others they looked like the scoria of a furnace, and appeared to be of volcanic origin, but nowhere did I observe the appearance of anything like a crater.  In the lower or front hills the rock was argillaceous, of a hard slaty nature, and inclined at an angle of about 45 degrees from the horizontal.  This formation was frequently traversed by dykes of grey limestone of a very hard texture.

Upon watering the horses at the hole in the rock, I was much disappointed to find that they had already sunk it eighteen inches, and now began to fear that it would not last them so long as I had anticipated, and that I should still be obliged to cross over the hills to the very rocky channel where I had found permanent water on the 15th of July.  This I was desirous, if possible, to avoid, both from the difficult nature of the road by which that water must be reached, and from the circumstance that it was going so much out of our way into an all but impracticable country, and that consequently, when we did move on again to the north, we should be obliged to come all the way back again over the same bad road to gain the open country under Flinders range, where alone we could hope to make any progress with the drays.