314 Dr. C. A. Cotton—Later Geological 
V.—Tar Srructure anv Later GerontocicaL History oF 
New ZEALAND. 
By C. A. Corton, D.Sc., F.G.S., Victoria University College, Wellington, N.Z. 
(Concluded from the June Number, p. 249.) 
UPPORTED by the great weight of Hutton’s authority, his views, 
with which those of Haast 1 and the early views of Hector” were 
in general agreement, have gained wide acceptance, notwithstanding 
the opposition of McKay. Marshall, for example, as late as 1911 wrote 
as follows: ‘‘ The great elevation [ Mesozoic orogenic movement] was 
succeeded by nearly as great a depression. The majestic mountain 
ranges were gradually lowered until nothing but a chain of islands 
showed above sea level. ‘lo what a great extent this movement 
prevailed is seen at Lake Te Anau, where the Oamaru formation, 
some 8,000 feet thick, rises to the tops of the mountains. At 
Wakatipu and in the Rangitata valley the Oamaru rocks are found 
in the recesses of the mountains. In the Trelissick basin and 
between the masses of the Kaikoura ranges there was deep water. 
The valleys of the tributaries of the Buller are filled with Oamaru 
sediments.” § 
Brief reference may here be made to the effects of the Kaikoura 
movements, though anything like a complete account of the structure 
and surface forms produced cannot be attempted. In Marlborough 
the great reverse faults, first noted by McKay, and the huge tilted 
and compressed blocks from which the Kaikoura ranges have been 
carved are most impressive.* Though less intense the effects in 
North Canterbury are similar in kind, and a geological map of the 
district would present the appearance of a mosaic of ‘ oldermass’ and 
‘covering strata’ formations as a result of block faulting, with the 
preservation of the latter on the lower blocks and their removal by 
erosion from the higher. 
Some remarkable intermontane basins occur as a result of these 
movements,° and the rivers that cross the basins flow out of them by 
way of deep, perhaps antecedent gorges across the oldermass of the 
upthrown blocks. ‘The largest of these structural basins, the Waiau— 
Hurunui Plain, may be mentioned as an example. It is traversed 
by two rivers of considerable size, the Hurunui and the Waiau, 
which, curiously enough, make their way out by separate gorges, 
while the lowest initial gap in the basin rim—as indicated by the 
structure of the covering strata—is not occupied by a stream at all. 
A railway enters the basin from the south by way of this gap. The 
covering strata are in part preserved in the low-lying interior of the 
1 J. von Haast, ‘‘On the Geology of the Waipara District’’: Col. Mus. 
and Geol. Surv. of N.Z., Rep. Geol. Expl. 1870-1, pp. 5-19, 1871. 
2 J. Hector, ‘‘On the Geology of the Manuherikia Valley’’: Otago Prov. 
Goy. Gaz., 1862. 
3 P. Marshall, ‘‘New Zealand and Adjacent Islands’’: Handbuch reg. 
Geol., Bd. vii, Abt. i, p. 40, Heidelberg, 1911. 
4 See C. A. Cotton, ‘‘ Physiography of the Middle Clarence Valley ’’: Geo- 
graphical Journal, vol. xlii, pp. 225-46, 1913. 
5 R. Speight, ‘‘ The Intermontane Basins of Canterbury’’: Trans. N.Z. 
Inst., vol. xlvii, pp. 336-53, 1915. 
