Brenson.—Structural Features of the Margin of Australasia. 199 
is most intense in the eastern half, though without extensive overfolding ; 
but on the western side it is more open, and the strata are un ulating 
except where they are shattered by the broad crush-zones as shown by 
the recent investigations of Henderson and Ongley (1923). The same 
trend continues through the Kaikoura Mountains of the South Island, 
though a north-easterly strike is marked near the line of separation 
between the Palaeozoic rocks in the north-western portion of that 
Island and the Permian to Mesozoic rocks which make up the Southern 
Mountains, and the gneissic granodiorites of the south-west, appear to have 
been erupted at this period, proof of the intrusion of the granodiorite 
into the annelid-bearing Permian or Triassic sediments having recently 
been obtained by Moir and also by Park (1921). ` 
In the southern half of the South Island of New Zealand the main 
ranges bifurcate. One branch, containing the Palaeozoic sediments and 
granodiorites, continues to the south-south-west through Fiordland, bending 
later to the south-east into Stewart Island ; the other range bends directly 
to the south-east, running through Central Otago, and consists of the 
problematical Otago schists. These form a broad anticlinal mass of 
sericitic schist, usually appearing to pass laterally and vertically 
into fossiliferous Permian (?) and Triassic greywackes, &c., though 
west boundary of Otago a syncline (largely covered by Recent alluvium) 
and a sharp anticline of fossiliferous Triassic greywackes (forming the 
undulating unaltered Mesozoic se thland, which are wedged 
in between the two branches of the bifurcating range, as indicated above. 
Suess terms this bifurcation the meeting of two unilateral chains in 
detritus derived from the schists on which they rest, as demonstrated by 
's view that the 
lying schists may really be a packet of recumbent folds. This explanation 
was also independently conceived by the writer (Benson, 1921), with the 
addition that the Hokonui anticline was considered as a Parma-like forefold 
separating the overfolded area from the resistant massif beneath South- 
and; and, further, the existence of fault-blocks bringing the slightly 
altered upper recumbent folds down among the lower folds and more 
metamorphosed rocks was suggested as a means of explanation of the 
occurrence of rectilinearly and rather sharply bounded areas of greywacke 
among the micaceous schists. The lack of recognizable horizons, however, 
will long prevent the adequate testing of these hypotheses. It is to be 
noted that plutonic intrusions are almost entirely absent from the region 
5—Trans. 
