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Show 224 PATAGONIA. April, 1834. the momentum gained by the rapid descent seemed to urge the bird upwards, with the even and steady ~ove~ent of a paper kite. In the case of any bird ~oaring, Its ~o~10n must be sufficiently rapid, so that the actiOn of the mclined s~rface of its body on the atmosphere, may counterbalance Its gravity. The force to keep up the m?me.ntum. of a bo~y moving in a horizontal plane in that flm.d (m W~ICh there ~s so little friction) cannot be great, and this force IS all that IS wanted. The movement of the neck and body of the condor, we must suppose, is sufficient for this. However this may be, it is truly wonderful and beautiful to se~ so great a bird, hour after hour, without any apparent exertiOn, wheel~ ing and gliding over mountain and river. APRIL 29TH.-From some high land we hailed with joy the white summits of the Cordillera, as they were seen occasionally peeping through their dusky envelope of clouds. During the few succeeding days, we continued to get on slowly, for we found the river-course v~ry tor~ous, and strewed with immense fragments of vanous anCient slaty rocks, and of granite. The plain bordering the valley h~d here attained an elevation of about llOO feet, and Its character was much altered. The well-rounded pebbles of porphyry were in this part mingled with many immense angular fragments of basalt and of the rocks above mentioned. The first of these erratic blocks which I noticed, was sixty-seven miles distant from the nearest mountain; another which had been transported to rather a less dis~ tance, measured five yards square, and projected five feet above the gravel. Its edges were so angular, and its size so great, that I at first mistook it for a rock in situ, and took out my compass to observe the direction of its cleavage. The plains here were not quite so level as those nearer the coast, but yet, they betrayed little signs of any violent action. Under these circumstances, it would be difficult, as it appears to me, to explain this phenomenon on any theory, excepting through that of transport by ice while the country was under water. But this is a subject to which I shall again recur. May, 1834. VALLEY OF ST. CRUZ. 225 During the two last days we met with signs of horses, and with several small articles which had belonged to the Indians, -such as parts of a mantle and a bunch of ostrich feathersbut they appeared to have been lying long on the ground. Between the place where the Indians had so lately crossed the river and this neighbourhood, though so many miles apart, the country appears to be quite unfrequented. At first, considering the abundance of the guanacoes, I was surprised at this ; but it is explained by the stony nature of the plains, which would soon disable an unshod horse from taking part in the chase. Nevertheless, in two places in this very central region, I found small heaps of stones, which I do not think could have been accidentally thrown together. They were placed on points, projecting over the edge of the highest lava cliff, and they resembled, but on a small scale, those near Port Desire. MAY 4Tn.-Captain FitzRoy determined to take the boats no higher. The river had a winding course, and was very rapid ; and the appearance of the country offered no temptation to proceed any further. Every where we met with the same productions, and the same dreary landscape. We were now one hundred and forty miles distant from the Atlantic, and about sixty from the nearest arm of the Pacific. The valley in this upper part expanded into a wide basin, bounded on the north and south by the basaltic platforms, and fronted by the long range of the snow-clad Cordillera. But we viewed these grand mountains with regret, for we were obliged to imagine their form and nature, instead of standing, as we had hoped, on their crest, and looking down on the plain below. Besides the useless loss of time which an attempt to ascend any higher would have cost us, we had already been for some days on half allowance of bread. This, although really enough for any reasonable men, was, after our hard day's march, rather scanty food. Let those alone who have never tried it, exclaim about the comfort of a light stomach and an easy digestion. 5Tn.-Before sunnsc we commenced our descent. We VOL. III. Q |