68 REPORT—1846. 
black, rugged and honeycombed surface, and white interior, sometimes crystalline, 
at others earthy and powdery, and occasionally exhibiting a coralline structure. 
Within the delta of the river Kediri, there are small island-like masses of the same 
rock; and in one of these were nodules of chert and coarse earthy limestone, with 
small bivalve shells (Venus, or Cyrena). Along the south coast of the eastern end 
of Java are some great calcareous formations, containing fossils, which were noticed 
by Dr. Horsfield in his geological map of Java. From all these particulars, the 
author concludes that a great tertiary formation of very recent origin—and being, in 
fact, but a raised fringing reef—clings to the flanks of all the volcanic islands from 
the east end of Timor to the west end of Java; and that, narrow as these islands 
are in proportion to their length, their actual volcanic portion is confined within 
still narrower limits; and huge as are the piles of volcanic materials gradually accu- 
mulated in some of the mountains, they owe a good part of these materials, and 
their elevation also, to a comparatively recent period in the earth’s history, during 
the existence of creatures now living on the earth. 
Sketch of the Geological Structure of Australia. 
By J.B. Juxes, M_A., F.G.S. 
This document was chiefly drawn up from the author’s own observations during 
four years, in which he had opportunity, as naturalist of H.M.S. Fly, of seeing the 
greater part of the Australian coast. Along the eastern coast there is one con- 
tinuous line of hills, extending from Bass’s Straits to Cape York in Torres Straits, a 
distance of 2400 miles; beyond which it is prolonged in rocky islands up to the 
coast of New Guinea. This chain has a granitic axis, flanked by metamorphic and 
palzozoic rocks in the south, as described by Count Strzelecki. From Port Bowen, 
in lat. 22° 30’, the author’s own observations commenced. The coast principally 
consisted of schists, porphyries and basalts; at Cape Upstart granite occurred, and 
was extensively developed on the coast to the northward, and far into the interior, 
forming hills 4000 feet high. North of Cape Melville, the granite almost disap- 
peared; and instead, great masses of porphyry with felspathic, quartzose and me- 
tamorphic rocks composed all the headlands and islands. ~ This line of coast appears 
to cut obliquely through a chain having granite for its axis, flanked by porphyries 
and mietamorphic rocks.” On the south-east coast, the crest of the main chain lies 
70 or 100 miles from the shore, leaving a considerable space, which is occupied by 
stratified rocks, consisting of palzozoic shales, sandstones, &c. The same rocks are 
found on the western flank of the chain, in the district of Port Phillip, and its coal- 
beds exist at Western Port. West of the coast range granite shows itself in the bed 
of the Bogan, just before it enters the Darling, and in the upper parts of the Gle- 
nelg. South of the Murray, it forms the north and south ranges of the Pyrenees, - 
the range of Mount Byng, &c. The great mass of the Grampians, more than 4000 
feet high, is composed of sandstone similar to that of Sydney ; south of which are a 
number of volcanic cones and vast sheets of lava. Over all the lower parts of the 
country, from Port Phillip to the Murray, is spread a great tertiary formation, 
abounding in shells, echinoderms, and corals. At Cape Jervis, South Australia, 
the rocks consist of mica-slate, gneiss and clay-slate ; and at Adelaide of coarse 
chlorite schist, and about Gawler Town, blue clay-slate prevails. Veins of copper 
and lead abound in the various ranges. The interior appears to consist everywhere 
of tertiary clays and sandstone; which also form the coast, for 600 miles, from 
Streaky Bay on the east to Mount Ragged on the west of the Great Bight. About 
Mount Ragged granite is again seen, and frequently forms hills to the west, whose 
bases are concealed by the tertiary. From King George’s Sound, an elevated di- 
strict runs northward at least 250 miles, consisting of granite, metamorphic rocks, 
gneiss, &c. Between this district and the sea, is a low plain, twenty miles wide, of 
recent tertiary rocks, which extend northward to the islands forming the western 
boundary of Shark’s Bay, forming the whole western coast of the Swan River 
Colony. Along the north-west coast from Shark’s Bay to Dampier’s Land is a vast 
tract of flat country, scarcely raised above the sea level, and fronted by dunes of 
sand. Between Collier’s Bay and Cambridge Gulf is a great promontory of strati- 
fied sandstone like that of Sydney. The next portion of the coast described from 
personal observation is that at Port Essington, which consists of a red or white fer- 
st 
