Park. — Geological History of Eastern Marlborough. 67 



In 1916 Cotton gave the name " Kaikoura movements " to the Pliocene 

 uplift that affected eastern Marlborough. I was the first (1905, pp. 501-2, 

 and 1910, p. 110) to recognize and describe the differential character of 

 this uplift, and should prefer the name " Ruahine movement." In the 

 Ruahine Range the effects of differential axial elevation are better dis- 

 played than elsewhere. Moreover, Professor Suess (1909) included the 

 Ruahine Range of New Zealand in his Third Australian Arc of folding, 

 elevation, and vulcanicity, and used the name " Ruahine " as representa- 

 tive of the uplift and vulcanicity of that region. I think the term 

 " Ruahine movement " ought to stand. 



Synopsis. 



My view is that the folding and elevation of the Juro-Triassic and older 

 rocks took place in the pre-Albian period of the Lower Cretaceous. This 

 orogenic movement, which I have called the " Rangitatan movement," 

 gave birth to the existing N.E.-S.W. axial chains of New Zealand. The 

 folding was accompanied by fracturing, faulting, and subsidence along lines 

 of structural weakness. The climatic conditions were pluvial, and the 

 denudation of the newly uplifted chains was relatively rapid. 



During the Albian, while the peneplaining of the mainland was in 

 progress, the sea began to invade the Clarence depression, where it laid 

 down Albian sediments. At the close of the Albian the Cenomanian 

 transgression became general, and soon the sea encroached on the newly 

 formed peneplain, Tahora,* that everywhere fringed the remnants of the 

 main chains. On the surface of this peneplain, and on the Albian beds 

 already deposited in the Clarence depression, sediments were laid down 

 throughout the remainder of the Upper Cretaceous period. 



Then followed the Eocene uplift, during which the weak post-Albian 

 beds were removed from the greater part of the uplifted Tahoran pene- 

 plain and from the Clarence depression. At the close of the Eocene began 

 the Oamaruian subsidence, during which the great Miocene formation was 

 deposited, in some areas on the slightly eroded surface of the surviving 

 Cretaceous strata, but mainly on the surface of the recently uncovered 

 peneplain. 



At the close of the Miocene there began a differential uplift in Otago 

 and Auckland, pivoting on the Napier-Wanganui zone, where the move- 

 ment still continued downward, this arising from the thrust accompanying 

 the tilting of the ends of the main chains. 



Before the advent of the newer Pliocene the Marlborough and north 

 Hawke's Bay areas were raised above sea-level. In the Napier-Wanganui 

 zone the deposition of marine sediments continued till the close of the newer 

 Pliocene, when this region also rose above sea-level. 



During the succeeding Pleistocene the alpine chains and the Kaikouras 

 were covered with ice-fields that fed the Clarence glacier, which, in my 

 opinion, formed the great post-Miocene conglomerate. 



Geological History. 



In Marlborough we are confronted with geological and physiographic 

 conditions altogether unlike those prevailing along the main axial chain. 

 The Inland Kaikoura and Seaward Kaikoura Mountains are w<dl-defined 

 ranges composed of folded argillites and greywackes of Juro-Triassic age, in 



* In Maori, tahora = great plains and low-lying maritime lands. 



