Benson.—Structural Features of the Margin of Australasia. 123 
though superficially one of block-faulting, is essentially a continuation of 
t iocene orogeny, and that cross-faulting “of the blatter type," and 
volcanic eruption, have led to the present distribution and structure of 
the island masses. 2 
Seismological investigation shows that the crust-movements аге still 
in progress in the outer arc. To the east of the New Hebrides the sea- 
floor slopes comparatively gently to a depth of 2,000 fathoms, but to the 
it sinks rapidly to a depth of 4,490 fathoms (fig. 3), so that the 
w 
ridge is strongly asymmetric, its steeper slope facing towards Australia, 
more immedi 
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growing member of Suess's first Australian arc. Thence it passes through 
New Britain into New Guinea, and westward through this last island into 
the Charles Louis Range. It is in northern New Guinea that the seismic 
о 
Moluccas. Аз in the New Hebrides, the chief epicentres are under water, 
and lie on the steep slope leading down írom the southern coasts of 
sh 
folds are cut off by the present coas : : 
Return may now be made to the inner portion of the first Australian 
are, consisting of the south-eastern extremity of New Guinea and the 
chain are reef-masses covering a string of volcanoes built up from eruptions 
