Volume 14 Australasia - dana ward's homepage

—THE AUSTR.1LIAN SEAS AXD ISLANDS.3G3by a general upheaval of less than twenty-five fathoms, and Tasmania, which waslong supposed to form part of the neighbouring continent, really belongs to itfrom the geological point of view. The presence of glaciers probably contributedto preserve the primitive form of the Tasmanian seaboard, all the south side ofwhich is carved into creeks and inlets, evidently ancient fjords which have maintainedtheir original depth and outlines.A close resemblance to the sea which formerly flooded South Australia, is presentedby the channel at present separating this continent from New Guinea.Between Cape York and Mount Cornwallis at the narrowest part of Torres StraitFig. 15G.Bass Steait.Scale I 5,553,000.Depths.100 Fathomsand upwards.the water is nowhere more than eleven or twelve, while the average scarcelyexceeds seven fathoms. It was shown by the accurate surveys of the F/i/ andBramble (1842—1847) that, even by keeping to the windings of the deepestchannel, a vessel drawing over 30 feet could only pass through in perfectlysmooth water. The rocky islets in this strait, whether isolated or grouped inclusters, consist exclusively of porphyries or syenites, like the rocks in the northernpeninsula of Queensland, of which they evidently form a seaward extension.East of these reef-fringed islets, between which flow channels perfectly free