In the distance some very level topped, dark looking cliffs, were seen at the summits of elevated ranges, which Mr. Darwin thought must have a capping or coating of lava. Of course we were very anxious to verify a fact so curious, and at noon were quite satisfied that it was so, having approached to the foot of a height thus capped, whose fragments had in falling not only scattered themselves over the adjacent plain, but into the bed of the river, in such a manner as to make the passage exceedingly dangerous; because large angular masses, in some places showing above the stream in others hidden beneath, but so near the surface that the water eddied and swelled over them, menaced destruction to the boats as they were with difficulty dragged through the eddying rapid; sometimes the rope caught under or around one of those masses, and caused much trouble. Near the spot where we stopped at noon there is a glen, quite different in character from any place we had passed. Indeed, upon entering the lava district, or that part of the country over which lava formerly flowed, there was no longer a Patagonian aspect around. Steep precipices, narrow, winding vallies, abundance of huge angular fragments of lava, a more rapid and narrower river, and plains of solid lava overlying the whole surface of the country, make this district even worse in its appearance than the eastern coast of Patagonia. Excepting in an occasional ravine nothing grows. Horses could not travel far, the ground being like rough iron; and water, excepting that of the river and its tributary in Basalt Glen, is very scarce.
The glen above mentioned is a wild looking ravine, bounded by black lava cliffs. A stream of excellent water winds through it amongst the long grass, and a kind of jungle at the bottom. Lions or rather pumas shelter in it, as the recently torn remains of guanacoes showed us. Condors inhabit the basaltic cliffs. Near the river some imperfect columns of basalt give to a remarkable rocky height, the semblance of an old castle. Altogether it is a scene of wild loneliness quite fit to be the breeding place of lions.
No signs of human visitors were discovered: indeed, the nature of the country must almost prevent horsemen from traversing these regions, there is so little food and such bad ground: only in glens or ravines such as this can any grass or bushes be found. Guanacoes absolutely swarm upon the heights, a consequence probably of their being undisturbed. They spread over the face of the high country like immense flocks of sheep.
During a long walk this evening Mr. Stokes and I were repeatedly disappointed by the mirage over an extensive stony plain, between two bends of the river. We were tired and very thirsty, and went from one apparent piece of water to another, only to be tantalized and to increase still more our dilemma.