Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.1): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

GEOLOGICAL KEMAUKS. 579 the granite from the greenstone and mica slate districts, is through- out thickly strewed with islands, which reduce the channel in some parts to a mile, and, in one place, to not more than fifty yards in width. Here, of course, the tide sets with great strength. Several vessels, however, have passed through it under sail; and one ship, a whaler belonging to Messrs. Enderby, working through ithe Strait, and finding much difficulty in passing to the westwards bore up, and, the wind being fair and the distance to sea only fifty miles, ran through it without accident. The land to the westward of the Bai-bara Channel is high and rugged ; and although in the vallies, ravines, and sheltered nooks, there is no want of vegeta- tion, yet, in comparison with the eastern part of the Strait, it has 3. very dismal and uninviting appearance. It was called by Sar- miento, ' Santa Ines Island' ;* but Narborough called it, ' South Desolation ; it being,' as he says, ' so desolate land to behold.'f Clarence Island, which is fifty-two miles long and twenty-three broad, although equally rocky, is much more verdant in appear- ance. The uniform direction of the headlands of the north shore of the island is remarkable. Upon taking a set of angles with the theodolite placed upon the extremity of the west end of Bell Bay, opposite to Cape Holland, the most prominent points to the south- east, as far as could be seen, were all visible in the field of the telescope at the same bearing. The same thing occurred on the opposite shore of the Strait, where the projections of Cape Gallant, Cape Holland, and Cape Fro ward, are in the same line of bearing; so that a parallel ruler placed on the map upon the projecting points of the south shore, extended across, will also touch the headlands of the opposite coast. The eastern island, which had been previously called, and of course retains on our chart the name of King Charles South Land, extends from the entrance of the Strait to the outlet of the Barbara and Cockburn Channels, at Cape Schomberg. The northern part partakes of the geological character of the eastern portion of the Strait. The centre is a continuation of the slate formation, which is evident at a glance, from the uniformity of the direction of the shores of Admiralty Sound, the Gabriel Channel, and all the bays and mountain ranges of Dawson Island. The south shore, or seaward coast line, is principally of greenstone, * Sarmienlo, p. 180. t Narborough's Voyage, p. 7^