Captain Flinders, in describing the position of the chains of islands on the north-west coast of Carpentaria, Wessel's, the English Company's, and Bromby's Islands, remarks, that he had "frequently observed a great similarity both in the ground plans, and the elevations of hills, and of islands, in the vicinity of each other, but did not recollect another instance of such a likeness in the arrangement of clusters of islands."* The appearances which called for this observation, from a voyager of so much sagacity and experience in physical geography, must probably have been very remarkable; and, combined with information derivable from the charts, and from the specimens for which we are indebted to Captain King and Mr. Brown, they would seem to point out the arrangement of the strata on the northern coasts of New Holland.
(*Footnote. The following are the proportions assigned by Captain de Freycinet to the principal divisions of the globe. Voyage aux Terres Australes page 107.
COLUMN 1: DIVISION OF THE GLOBE.
COLUMN 2: AREA IN FRENCH LEAGUES SQUARE.
COLUMN 3: PROPORTION.Asia : 2,200,000 : 17.
America : 2,100,000 : 17.
Africa : 1,560,000 : 12.
Europe : 501,875 : 4.
Australia : 384,375 : 3.The most remote points from the coast of New South Wales, to which the late expeditions have penetrated (and the interior has never yet been examined in any other quarter) are not above 500 miles, in a direct line from the sea; the average width of the island from east to west being more than 2000 miles, and from north to south more than 1000 miles.)
(*Footnote. Flinders 5 2 page 246; and Charts, Plates 14 and 15. King's Charts, Plate 4.)
Of the three ranges which attracted Captain Flinders' notice (see the Map) the first on the south-east (3, 4, 5, 6, 7) is that which includes the Red Cliffs, Mallison's Island, a part of the coast of Arnhem's Land, from Cape Newbold to Cape Wilberforce, and Bromby's Isles; and its length, from the mainland (3) on the south-west of Mallison's Island, to Bromby's Isles (7) is more than fifty miles, in a direction nearly from south-west to north-east. The English Company's Islands (2, 2, 2, 2) at a distance of about four miles, are of equal extent; and the general trending of them all, Captain Flinders states (page 233) is nearly North-East by East, parallel with the line of the main coast, and with Bromby's Islands. Wessel's Islands (1, 1, 1, 1) the third or most northern chain, at fourteen miles from the second range, stretch out to more than eighty miles from the mainland, likewise in the same direction.
MAP OF THE CHAINS OF ISLANDS ON THE NORTH-WEST COAST OF CARPENTARIA
It is also stated by Captain Flinders, that three of the English Company's Islands which were examined, slope down nearly to the water on their west sides; but on the east, and more especially the south-east, they present steep cliffs; and the same conformation, he adds, seemed to prevail in the other islands.* If this structure occurred only in one or two instances, it might be considered as accidental; but as it obtains in so many cases, and is in harmony with the direction of the ranges, it is not improbably of still more extensive occurrence, and would intimate a general elevation of the strata towards the south-east.
(*Footnote. Flinders Volume 2 page 235.)
Now on examining the general map, it will be seen, that the lines of the coast on the mainland, west of the Gulf of Carpentaria, between Limmen's Bight and Cape Arnhem--from the bottom of Castlereagh Bay to Point Dale--less distinctly from Point Pearce, latitude 14 degrees 23 minutes, longitude 129 degrees 18 minutes, to the western extremity of Cobourg Peninsula, and from Point Coulomb, latitude 17 degrees 20 minutes, longitude 123 degrees 11 minutes, to Cape Londonderry, have nearly the same direction; the first line being about one hundred and eighty geographical miles, the second more than three hundred, and the last more than four hundred miles, in length.* And these lines, though broken by numerous irregularities, especially on the north-west coast, are yet sufficiently distinct to indicate a probable connexion with the geological structure of the country; since the coincidence of similar ranges of coast with the direction of the strata, is a fact of very frequent occurrence in other parts of the globe.** And it is observable that considerable uniformity exists in the specimens, from the different places in this quarter of New Holland which have been hitherto examined; sandstone, like that of the older formations of Europe occurring generally on the north and north-west coasts, and appearing to be extensively diffused on the north-west of the Gulf of Carpentaria, where it reposes upon primitive rocks.***