OCR Text |
Show 284 TIERRA DEL FUEGO. June, 1834. ice had thawed all round it, so as to form a shallow pool of water. It was a cube of nearly two feet; and Mr. Bynoe with a maul knocked off, and brought away, a piece as large as a man's head. The iceberg was still floating, and drifting outwards : even if it had been stranded in the immediate neighbourhood, the block of granite would have rested on the clay-slate of the surrounding mountains. For the parent rock we must look to the higher parts of the range, near the head of the sound. Again, a few miles to the northward I see in the chart an Iceberg Sound, which no doubt was so called from the number of floating masses of ice. It may be recollected that in this latitude, on the opposite side of the Cordillera, the plains of St. Cruz, at the distance of fifty and sixty miles from the mountains, were strewed with great fragments of rock. Of these, one was sixty feet in circumference, and another, which was angular, measured five yards square ;both being partly buried in the gravel, so that their thickness was unknown. As it is probable that the plains were covered by the sea within a period geologically recent, and as we absolutely know, that icebergs at the present day, both in the same latitude and even further northward, are transporting angular blocks from the opposite side of the Cordillera, the explanation of the St. Cruz case through the same means of transport, is rendered so evidently probable, that we are not justified in doubting to receive it: more especially as the unbroken surface of those plains, and the terrace-formed valley, opposes a very great difficulty to the admission of any violent debacle. The latitudes which we have now been talking of, correspond to the southern extremity of Cornwall, and the northern provinces of France. I will add only one other case; namely, the occurrence of glaciers at the level of the sea, in the gulf of Penas, latitude 46° 40'. A glacier is represented in the charts as in one part abutting on a flat swamp qjten inundated, and in ano- June, 1834. GLACIERS. 285 ther reaching to the head of Kelly Harbour. The accompanying wood -cut is copied from the published charts. Captain King says its length is fifteen miles, and from the chart one part is seven broad ; it is also described as being lofty ; so that we here have an enormous mounta~n, c_over~ng a wide area, composed of ice. If we compare Its s1tuat~on with countries in the northern hemisphere, the corresponding parallel crosses the Alps of Switzerland. Or we may state the case stronger, by saying that glaciers here descend to the sea within less than nine degrees of latitude, from where palms grow, less than two and a half from arbore~cent grasses, and (looking to the westward in the same hemisphere) less than two from orchideous parasites, and within a single degree of tree-ferns ! In Norway, Von Buch found glaciers descending to the sea at Kunnen in latitude 67°; that is twenty degrees nearer the pole than in this hemisphere ;-a difference of latitude rather ~reater than that between the snow-lines of equal altitude in the same two countries. The survey of the inne·r coast terminated at the gulf of Penas, so that I am far from knowing whether glaciers are not . |