Geologists formerly would have brought into play the violent action of some overwhelming debacle; but in thi case such a supposition would have been quite inadmissible because, the same step-like plains with existing sea-shell lying on their surface, which front the long line of the Patagonian coast, sweep up on each side of the valley of Sant Cruz. No possible action of any flood could thus hav modelled the land, either within the valley or along the ope coast; and by the formation of such step-like plains or terraces the valley itself had been hollowed out. Although w know that there are tides, which run within the Narrow of the Strait of Magellan at the rate of eight knots an hour yet we must confess that it makes the head almost giddy t reflect on the number of years, century after century, whic the tides, unaided by a heavy surf, must have required t have corroded so vast an area and thickness of solid basalti lava. Nevertheless, we must believe that the strata undermined by the waters of this ancient strait, were broken u into huge fragments, and these lying scattered on the beach were reduced first to smaller blocks, then to pebbles an lastly to the most impalpable mud, which the tides drifte far into the Eastern or Western Ocean.
With the change in the geological structure of the plain the character of the landscape likewise altered. While rambling up some of the narrow and rocky defiles, I could almos have fancied myself transported back again to the barre valleys of the island of St. Jago. Among the basaltic cliffs I found some plants which I had seen nowhere else, bu others I recognised as being wanderers from Tierra de Fuego. These porous rocks serve as a reservoir for th scanty rain-water; and consequently on the line where th igneous and sedimentary formations unite, some smal springs (most rare occurrences in Patagonia) burst forth and they could be distinguished at a distance by the circumscribed patches of bright green herbage.
April 27th. -- The bed of the river became rather narrower and hence the stream more rapid. It here ran at the rat of six knots an hour. From this cause, and from the man great angular fragments, tracking the boats became bot dangerous and laborious
This day I shot a condor. It measured from tip to ti of the wings, eight and a half feet, and from beak to tail four feet. This bird is known to have a wide geographica range, being found on the west coast of South America from the Strait of Magellan along the Cordillera as far a eight degrees north of the equator. The steep cliff near th mouth of the Rio Negro is its northern limit on the Patagonian coast; and they have there wandered about fou hundred miles from the great central line of their habitation in the Andes. Further south, among the bold precipices at the head of Port Desire, the condor is not uncommon; yet only a few stragglers occasionally visit the seacoast. A line of cliff near the mouth of the Santa Cruz i frequented by these birds, and about eighty miles up th river, where the sides of the valley are formed by stee basaltic precipices, the condor reappears. From these facts it seems that the condors require perpendicular cliffs. I Chile, they haunt, during the greater part of the year, th lower country near the shores of the Pacific, and at nigh several roost together in one tree; but in the early part o summer, they retire to the most inaccessible parts of th inner Cordillera, there to breed in peace.
With respect to their propagation, I was told by th country people in Chile, that the condor makes no sort o nest, but in the months of November and December lay two large white eggs on a shelf of bare rock. It is said tha the young condors cannot fly for an entire year; and lon after they are able, they continue to roost by night, an hunt by day with their parents. The old birds generally liv in pairs; but among the inland basaltic cliffs of the Sant Cruz, I found a spot, where scores must usually haunt. O coming suddenly to the brow of the precipice, it was a gran spectacle to see between twenty and thirty of these grea birds start heavily from their resting-place, and wheel awa in majestic circles. From the quantity of dung on the rocks they must long have frequented this cliff for roosting an breeding. Having gorged themselves with carrion on th plains below, they retire to these favourite ledges to diges their food. From these facts, the condor, like the gallinazo must to a certain degree be considered as a gregarious bird In this part of the country they live altogether on the guanacos which have died a natural death, or as more commonl happens, have been killed by the pumas. I believe, fro what I saw in Patagonia, that they do not on ordinary occasions extend their daily excursions to any great distanc from their regular sleeping-places.