Cotton. — Notes on Wellington Physiography. 



261 



downthrown area. It is probable that these lines are only suggestions, for 

 on the accompanying section giving probable faults* two given on the map 

 are omitted and another is introduced. As mapped they are nearly parallel 

 to one another, and appear to coincide with the strike of the rocks. For 

 those bounding on the east and west the longitudinal ridges of Miramar 

 Peninsula and the Kilbirnie ridge to the west of it there appears to be 

 no evidence. The elongation of each ridge is satisfactorily explained as 

 corresponding to rock structure. Neither ridge has, on either side, a 

 straight or gently curved base-line, but sprawling spurs are given off (see 

 fig. 6). Both shores of Lyall Bay (figs. 1 and 6) directly facing the ocean 

 to the south are bounded by cliffs. That these are not fault-scarps there is 

 abundant proof in the extensive rock platforms at their bases, which were 

 raised above the sea by the small uplift of 1855. These prove a former 

 long seaward extension of the spurs. Where the tombolo (fig. 6) connects 

 Miramar Peninsula to the mainland this has afforded protection from 

 marine erosion, and the spurs run far out, that from Miramar Peninsula 

 almost meeting that from the mainland. To the north of the tombolo 

 in Evans Bay, on both shores, smaller scarps are found, fronted by 

 less-extensive rock platforms than those of Lyall Bay, all evidently the 

 work of the waves on Port Nicholson, the energy of which is very much less 

 than of those of the open sea. They are, however, sufficiently powerful, 



^M^mm^mm^m^^^rM^ //.v 



Fig. 11. — Eastern Shore of Port Nicholson, looking North-east from the 

 Signal-station on Miramar Peninsula. 



urged by the prevailing strong northerly winds, to account for the destruc- 

 tion of the relatively small bulk of the spurs and slopes, the removal of 

 which has resulted in the present scarped shore. 



Similar arguments can be used against the probability of a fault bounding 

 the harbour on the east. The shore-line is fairly straight for several miles 

 in the entrance, but the obvious reason for this is that it is the side of a low 

 narrow ridge, without lateral spurs, between two straight valleys. The 

 shore is subject to powerful wave-action, as it is not sheltered from waves 

 entering the harbour-mouth, and marine erosion has been able, by the 

 removal of quite a moderate amount of material, to cut a continuous line 

 of cliffs. 



Farther north, towards the head of Port Nicholson, the land is higher, 

 and no longer a narrow ridge. Torrent-gullies, opening to the harbour 

 as small bays, are separated by tapering spurs which run down nearly to 

 sea-level without change of slope. The points only of the spurs have been 

 truncated by wave-action, and a marked decrease in the height of wave- 

 cut facets can be traced northward on successive spurs. This appears to 

 correspond to the decreasing energy of waves, running along the shore, with 



* hoc. cit.. p. 539. 



