History of New Zealand. 247 
Picton! and one in the Makara Valley, Wellington,” are regarded as 
of Tertiary age. The exposures are so poor in each case that the 
form of the surface on which the beds were deposited cannot be 
ascertained. We are not under the necessity of believing that the 
surface must by that time have been reduced to a plain, for it may 
have been rejuvenated from time to time by uplift, though adjoiming 
areas where deposition was in progress were sinking. It is quite 
possible that portions of these districts have never been submerged 
since first uplifted by the Mesozoic movements, though the seulpturing 
to which they owe their present mountainous character followed 
much later uplift. Planation may well have happened more than 
once in the long intervening period. North-eastward of Wellington 
there is no evidence of submergence having taken place until rather 
late Tertiary times.® 
Farther to the north, in the centre of the North Islands, Speight * 
notes the presence of a plateau surface truncating the structure of 
the oldermass in the Kaimanawa Mountains, which he ascribes to 
marine erosion. The surface presumably passes under and forms the 
floor of the Tertiary beds (referred to the Miocene) of that district, 
which occur up to the height of 8,700 feet above sea-level. It 
appears probable from Speight’s description that the covering strata 
were formerly continuous across the island in the Kaimanawa area, 
and that the plateau of the higher part of the range has been stripped 
of its cover by erosion. 
In the south-eastern and north-western parts of the South Island 
the covering strata, with the exception of some of the basal beds, are 
mainly marine and of such a nature as to indicate that they 
-accumulated in an open sea where the supply of terrigenous sediment 
was very small. Though the total area over which these rocks now 
occur is not large, their former extension over a much wider area is 
proved by the presence of outliers. 
_ From the above considerations and from a general survey of what 
is known of the Tertiary rocks it is apparent that during the period 
of their deposition a great part of the site of the present islands of 
New Zealand was continuously submerged, and that very little of the 
remainder was left above water. 
It is important to note that the members of the covering strata, 
whether always strictly conformable or otherwise, appear to follow 
one another without discordance of dip, no satisfactory evidence to 
the contrary being known. Thus it may be stated that, except 
quite locally,® the only movements affecting the region after the 
1 A. McKay, Geol. Surv. N.Z., Rep. Geol. Expl., 1890, pp. 153-4. 
2 A. McKay, ‘‘ Report on Tertiary Rocks at Makara’’: Col. Mus. and Geol. 
Surv. N.Z., Rep. Geol. Expl., 1874-6, p. 54, 1877. 
3 J. A. Thomson, ‘‘ Mineral Prospects of the Maharahara District, Hawke’s 
Bay.’’: 8th Ann. Rep. Geol. Sury., Mines Statement, 1915, p. 165. 
2 R. Speight, ‘‘ Geological History ’’ in L. Cockayne’s Report of a Botanical 
Survey of the Tongariro National Park, Department of Land, C. 11, Welling- 
ton, 1908, p. 7. 
5 The hypothetical block movement which has been assumed in order to 
account for the Great Marlborough Conglomerate has been referred to on an 
earlier page. In a paper on the ‘‘ Structure of the Paparoa Range’’, read 
before the Geological Section of the Wellington Philosophical Society, 
