Cotton. — Notes on Wellington Physiography. 245 



Art. XXVII. — Notes on Wellington Physiography.* 



By C. A. Cotton, Victoria College, Wellington. New Zealand. 



[Read before the Wellington Philosophical Society, 4th October, 1911.] 



Plates XVIII-XXI. 



Contents. page 



Introduction . . . . • • • • • ■ • ■ 245 



Structure . . . . • • • • • • • • 245 



Land features . . . . . • • • • • ■ • 246 



Cycles of erosion . . . . ■ ■ • • • • 248 



Forms of the Kaukau cycle . . . . . . . . 249 



The Tongue Point cycle . . . . . . . . 250 



The present cycle . . . . . ■ 251 



The Port Nicholson area . . . . . . . . 251 



Coast features . . . . . . • • • ■ ■ ■ 254 



The cliffs . . . . . . . . • • . . 254 



The coast platforms . . . . ■ . • . ■ . 255 



The Wellington fault . . . . • • . . 257 



The fault-scarp . . . . • . . . 257 



Nature of the movement . . . . . . . . 259 



Other faults . . . . . . . . ■ • . . 260 



Changes in drainage of the Karori-Khandallah or " Long" Valley 262 



Type of topography . . . . . . • • • ■ 264 



Summary . . . . • • • • ■ • • • 265 



Introduction. 



In the preparation of these notes a detailed examination has been made 

 only of the district lying to the west of Port Nicholson, which for con- 

 venience will be referred to as the Wellington Peninsula. By means of 

 hasty traverses and observations made from a distance, however, it has 

 been possible to reach general conclusions which, the writer believes, hold 

 true for the whole of the district represented in the locality-map (fig. 1). 



Structure. 



With the exception of a few small patches of Recent sands and gravels 

 occurring as beaches and river-flats, the rocks are a single series of sandy 

 argillites and fine- and coarse-grained greywackes.f They are closely 

 folded in a complex manner, but, owing chiefly to the unfossiliferous cha- 

 racter of the rocks, the structure has not yet been unravelled. On any 

 cross-section rapid changes in the direction of dip are the rule, but the 

 attitude of the strata is so much more nearly vertical than horizontal that 

 as far as their effect on topography is concerned they may be regarded as 

 vertical. There has been no folding of any consequence in more than one 



* When this paper was written the writer had not seen the criticism of Bell's paper 

 by W. M. Davis in the Bulletin of the Am. Geogr. Soc. (vol. 43, No. 3, 1911, p. 190,. 

 Had he read that article earlier he would have been able to profit by several valuable 

 hints given by Professor Davis. 



t This thick, unfossiliferous series is correlated on lithological grounds with the 

 Maitai system of New Zealand geologists, which, according to Marshall (" New Zealand," 

 Handbuch reg. Geol., 7 Band, 10 Abt., p. 35, 1911), is of Trias-Jura age. The period of 

 folding is believed to be late Mesozoic. 



