“The desert over which we had passed, ninety miles from water to water, is an immense triangular plain, bounded on one side by the Colorado, on the west by the Cordilleras of California, the coast chain of mountains which now encircles us, extending from the Sacramento river to the southern extremity of Lower California, and on the north-east by a chain of mountains, running southeast and northwest.  It is chiefly covered with floating sand, the surface of which in various places is white, with diminutive spinelas, and everywhere over the whole surface is found the large and soft muscle shell.  I have noted the only two patches of grass found during the ‘jornada.’  There were scattered, at wide intervals, the Palafoxia linearis, Atriplex, Encelia farinosa, Daleas, Euphorbias, and a Simsia, described by Dr. Torrey as a new species.

“The southern termination of this desert is bounded by the Tecate chain of mountains and the Colorado; but its northern and eastern boundaries are undefined, and I should suppose from the accounts of trappers, and others, who have attempted the passage from California to the Gila by a more northern route, that it extends many days’ travel beyond the chain of barren mountains which bound the horizon in that direction.  The portal to the mountains through which we passed was formed by immense buttes of yellow clay and sand, with large flakes of mica and seams of gypsum.  Nothing could be more forlorn and desolate in appearance.  The gypsum had given some consistency to the sand buttes, which were washed into fantastic figures.  One ridge formed apparently a complete circle, giving it the appearance of a crater; and although some miles to the left, I should have gone to visit it, supposing it to be a crater, but my mule was sinking with thirst, and water was yet at some distance.  Many animals were left on the road to die of thirst and hunger, in spite of the generous efforts of the men to bring them to the spring.  More than one was brought up, by one man tugging at the halter and another pushing up the brute, by placing his shoulder against its buttocks.  Our most serious loss, perhaps, was that of one or two fat mares and colts brought with us for food; for, before leaving camp, Major Swords found in a concealed place one of the best pack mules slaughtered, and the choice bits cut from his shoulders and flanks, stealthily done by some mess less provident than others.

“Nov. 29.—­The grass at the spring was anything but desirable for our horses, and there was scarcely a ration left for the men.  This last consideration would not prevent our giving the horses a day’s rest wherever grass could be found.  We followed the dry sandy bed of the Cariso nearly all day, at a snail’s pace, and at length reached the ‘little pools’ where the grass was luxuriant but very salt.  The water strongly resembled that at the head of the Cariso creek, and the earth, which was very tremulous for many acres about the pools, was covered with salt.  This valley is not more than half a mile wide, and on each side are mountains of grey granite and pure quartz, rising from 1,000 to 3,000 feet above it.