502 Transactions. — Geology. 



In the Waipara district the same beds form ridges reaching 

 over 1,800 ft. high at their highest parts. 



The old Tertiaries at the lower end of the Takaka Valley 

 occur at sea-level, but they rise with the gradient of the valley, 

 and gradually ascend till in a distance of thirty miles they 

 reach Mount Arthur Tableland, 3,600 ft. above the sea, where 

 they are almost horizontal. JFrom the tableland going south- 

 ward the same beds cling to the western flanks of the main 

 range at elevations varying from 2,000ft. to 3,000 ft., descend- 

 ing westward towards the sea at Mokihinui and Westport and 

 intermediate places. This mantling fringe of Middle Tertiary 

 marine rocks ascending from sea-level on both coasts affords a 

 measure of the elevation of the land since the beginning of the 

 Pliocene, and, moreover, clearly proves the differential rate of 

 the upward movement 



The greatest elevation has in all cases taken place along 

 the main orographical axis of the Island, which is situated 

 closer to the west coast than the east. The differential land- 

 movement being most acute on the west coast introduced un- 

 equal stresses, which resulted in extensive faulting of the coal- 

 measures between the sea and the axis of greatest elevation. 

 A notable example of this faulting occurs in the Aorere Valley 

 near Collingwood. On the south side of the river the Ter- 

 tiaries lie at sea-level, but on the north side they crown the 

 range at an elevation of 1,000 ft., and dip away to the west 

 coast. 



Contemporary Volcanic Eruptions. 

 While the sediments of the Tertiary fringe were accumu- 

 lating on the littoral of the Miocene seas, volcanic eruptions 

 commenced in the area lying between Moeraki and Oamaru. 

 They were submarine, and took place at points lying some 

 miles to the seaward of the old shore-line, most notably in the 

 areas now known as Ngapara, Waiareka, Oamaru, and Kaka- 

 nui. These eruptions were not very violent ; and it was only 

 at Kakanui, and perhaps at Oamaru, that the ejected materials 

 were piled up so as to form volcanic islands. So far as can 

 be ascertained from the distribution of the matter, the volcanic 

 activity began after the close of the Waihao-Kakahu horizon, 

 and ended before the deposition of the Waitaki Stone began. 

 The main outbursts were apparently confined to the Mount 

 Brown or Hutchinson Quarry period. 



There is reason to believe that the volcanic eruptions in the 

 Hauraki Gulf area which produced the tuffs interbedded with 

 the Waitematas were contemporary with those near Oamaru. 



Life of Oamaru Series. 



At the time of the deposition of the sediments of this 

 formation there lived in the New Zealand seas a zeuglo- 



