Benson, —Siructural Features of the Margin of Australasia. 119 
and plutonic rocks associated with indurated slates, grey limestones 
sandstone, and conglomerate on Woodlark Island. On this i csi 
folded Miocene limestones rest. The whole D'Entrecasteaux Group appears 
formerly to have been united to New Guinea, and to have been separated 
therefrom and subdivided by east-west rifts accompanied by volcanic 
activity, and followed by meridional rifting and renewed vulcanicity. In 
both Woodlark Island and the Louisiades raised and tilted coral-reefs are 
a characteristic feature (Stanley, 1912, 1915).+ 
In regard to the trend-lines of the aor coast and the Finisterre 
Ranges (the Tertiary and Mesozoic rocks in which Suess considered “ the 
outer boundary of the folded range which сат succeeds them to 
the south "), Stanley (1923) no longer considers them as a portion of the 
same tectonic zone as the main ranges of ә island, but, following a 
эе made by Suess, views them as a separate geanticline “ * of 
maller dimensions, with a probable Asiatic ненна and thereby related 
E Halmahera, the Philippines, and Japan. This coastal feature i is modified 
by faults or steep folds, which cut obliquely the geanticlinal axis" (cf. 
Suess, 1909, p. 308). This axis, he believes, bends eastwards in the 
uon Peninsula, and extends into New Britain AR 19214). Parallel 
to it runs a line of active volcanic islands (the Schouten Group) from 
beyond the mouth of the Sepik River across ыш Strait, and this is 
continued by the great series of volcanoes along the northern coast of 
New Britain. Kober's view, on the other hand, seems to regard the north- 
coast ranges as forming the northward-thrust lateral portion of a single 
orogen comprising the whole of the highlands of New Guinea. 
The south-eastern portion of New Guinea thus affords several interesting 
problems. Suess (1909) groupe. the whole of this island series, together 
with New Britain, the Solomons, New Hebrides, New Caledonia, and 
northern New Zealan d, into a single great system, which he terms 
‘the first Australian arc," recognizing, however, an inner and an outer 
portion. The former, which includes the a of New Guinea and the 
islands off the south-eastern extremity, m thaps be considered to be 
= одаи also in New Caledonia ; ham latter is that containing the 
marck Archipelago, the Solomons, and New Hebrides. As held by 
various writers, especially David, Andrew ws, and Jensen, whose views were 
summarized in a previous paper (Benson, 1923), Australia grew generally 
from the south-west towards the north-east and east. It appears in 
accord with this that the и crustal activity, both seismic and 
volcanic, is very marked in the outer portion of the arc, and to a less 
degree in the inner, and then only near the recently fractured areas of 
New Guinea, away from which, both to the east and to t Me west, ге 
activity diminishes. There seems, indeed, reason for 
Stanley does (1921), two distinct arcs—the outer fairly DUE bebes 
only by narrow transverse subsidences, the inner very discontinuous and 
largely submerged. The precise rôle of New Britain is, however, almost 
as indefinite as that of the Kei Islands, though even if it be no more than 
an arcuate horst it cannot be considered as exactly analogous with the 
Kei Islands. As will appear, however, it does seem to be much more 
probable that it is a definitely folded arc. 
* The strike of this limestone is N. 20° E., or approximately at right angles to оны, 
general trend of the line, probably indicating a strong local flexure adjacent to a cro 
fault. 
T For a recent detailed account of the coral-reefs of these islands, based for the 
most part on a study of the British Admiralty charts, see Davis, 1922 
