As we proceeded, the country changed to extensive plains and undulations of stones and gravel, washed perfectly level by water, and with the stones as even in size and as regularly laid as if they had been picked out and laid by a paviour. At intervals were interspersed many of the fragments of table land I have alluded to before, only perhaps a little less elevated than they had previously been; we passed also the beds of several small dry watercourses, and encamped upon one of the largest, long after dark, having travelled twenty-five miles since we left the cart, and having made in the whole a day's journey of thirty-seven miles. There was tolerable food in the bed of the watercourse, but the horses were thirsty and eat but little. Unfortunately, in crossing the stony ground, one of them cast a shoe, and began to go a little lame. August 14.--Moving away very early we travelled sixteen miles due north, through a very similar country, only that the stones and gravel in the plains had become much finer and a good deal mixed with sand; the fragments of table land still continued in every direction at intervals, and their elevations still varied from 50 to 300 feet. In the upper part these elevations appeared red from the red sandy soil, gravel, or iron-stone grit which were generally found upon their summits. They had all steep precipitous sides, which looked very white in the distance, and were composed of a chalky substance, traversed by veins of very beautiful gypsum. There were neither trees nor shrubs, nor grass, nor vegetation of any kind except salsolaceous plants, and these every where abounded. In the midst of these barren miserable plains I met with four natives, as impoverished and wretched looking as the country they inhabited. As soon as they saw us they took to their heels, apparently in great alarm, but as I was anxious to find out from them if there was any water near, I galloped after two of them, and upon coming up with them was very nearly speared for my indiscretion; for the eldest of the two men, who had in his hand a long, rude kind of spear with which he had been digging roots or grubs out of the ground (although I could not see the least sign of anything edible) finding that he was rather close pressed, suddenly halted and faced me, raising his spear to throw. The rapid pace at which I had been pursuing prevented my reining in my horse, but by suddenly spurring him when within but a few yards of the native, I wheeled on one side before the weapon had time to leave his grasp, and then pulling up I tried to bring my friend to a parley at a less dangerous distance.