158 J. MALCOLM MACLAREN, ESQ., B.SC, F.G.S., ON 



at the outset is probably connected with tlie presence on the 

 coast further to the north of comparatively soft, easily 

 denuded rocks of Cretaceo-Teriiary and Lower Tertiary age. 



9. Form of the oceanic floor. — So far, soundings have not 

 been sufficiently numerous to show Avhether the submarine 

 valleys are indicated by seaward channels in the ocean floor. 

 But the probability of finding such channels is v^^ry remote, 

 for the south-west coast of New Zealand, instead of standing 

 on a submerged platform, as does Norway, slopes away 

 sharply to the Thomson Basin, between New Zealand and 

 Australia, with its average depth of 2,600 fathoms. This 

 contradiction of the axiomatic expression of recent Avriters — 

 that a deeply indented coast line stands on a submarine 

 platform — is perhaps, after all, only apparent. For, from 

 ;stratigrapliical conditions in the Southern Alps, which need 

 not, in this paper, be indicated further than to mention that 

 the Southern Alps themselves are probably the eastern half 

 of an anticline, the western position of which has dis- 

 appeared, a great fault line, with a hade to the Avest, is 

 assumed to pass down the west coast of the South Island of 

 New Zealand. Such a fault would at once reconcile fact 

 .and theory, and would, inter alia, account in a measure for 

 the extremely straight coast line shown in the sounds 

 region. 



10. Geological Histori/. — The geological history of the 

 isouthern portion of New Zealand, during the Tertiary 

 period, is, thanks to the succession of marine and lacustrine 

 beds in the south, and of marine beds in the north, com- 

 paratively easy to trace. The elevation which resulted in 

 the initial formation of those river channels Avhich are now 

 occupied by the sounds, took place either in Lower or Upper 

 Eocene times, according to whether we follow Professor 

 Button or the officers of the New Zealand Geological Survey 

 in the grouping vf the Lower Tertiary rocks. The former 

 insists on an unconformity, between the Waipara and 

 Oamaru formations, representing a period of elevation at 

 that time — equivalent probably to Lower Eocene — while the 

 latter, broadly speaking, group the beds together as Cretaceo- 

 Tertiary, thus throwing the unconformity into Upper Eocene 

 xime. Whatever the correct interpretation may be, it is 

 certain, at least, that, in Lower Tertiary time, the Southern 

 Alps received their final foldings and flexures accompanied 

 by great upheaval, for all the beds since deposited he more 

 .or less horizontally on their flaidvs and moreover are 



