Cotton. — Warped Land-surface at Port Nicholson. 135 



Tilted Coastal Platforms. 



The Platforms farther West. — As previously noted by the writer (1912 ; 

 1916a), the coast both east and west of the entrance to Port Nicholson is 

 bordered by remnants of platforms cut by marine abrasion when the land 

 stood considerably lower than it does now. Around the shores of Port 

 Nicholson itself, and on the. partially drowned ridges immediately to the 

 west of the entrance, which form part of the deeply depressed area, no traces 

 of uplifted benches clearly referable to marine erosion are to be found above 

 the rock platform that was raised a few feet above sea-level in 1855. Since 

 parts of this shore-line have not suffered severe retro gradation by marine 

 erosion, some remnants of uplifted platforms should survive if such had 

 existed ; and it may therefore be assumed from their absence that this part 

 of the coast has always escaped uplift, or that any strands that have been 

 uplifted have been lowered again below sea-level. The profile of the sea- 

 bottom off shore, as revealed by soundings, does not show terraces such 

 as would be produced by submergence of cliff-bordered remnants of cut 

 platforms ; but this negative evidence has little significance, for the initially 

 sharp, well-defined subaqueous features that would be thus produced would 

 soon be obliterated by deposition of the large amount of waste supplied 

 from the neighbouring mountainous area of rather easily eroded rocks, 

 which are subject to strong marine as well as subaerial erosion. 



To the west of the depressed area the high-standing marine platforms 

 indicate uplift and a limited amount of deformation. Two such platforms 

 are distinctly recognizable (Cotton, 1912, fig. 7 ; 1916a, fig. 8), but only the 

 lower of these can be traced for any considerable distance along the coast. 

 At Tongue Point it is continuous as a broad shelf (except where intersected 

 by a large ravine) for two miles, and at the ravine, where a section of the 

 ancient beach at the rear of the platform may be seen, its height is 230 ft. 

 In this portion no variation in the height of the rear of the platform has been 

 observed, though its variable width, and especially its variable seaward 

 slope, give a false appearance of irregular variation in height when it is 

 viewed from the offing. For three miles farther westward, as far as Cape 

 Terawhiti, the platform is traceable continuously, though it is thickly 

 covered with talus and only at a few places is wide enough to form a dis- 

 tinct bench. When the cliffs are viewed from the sea, however, the top of 

 the talus-covered wave-cut platform can be distinctly traced all the way, 

 and where the bench is narrow this cannot be far below the ancient strand- 

 line, which is thus seen to descend gradually to a height of about 100 ft. at 

 Cape Terawhiti. 



It appears, therefore, either that this portion of the coast was uplifted 

 with a gentle westward tilt, or that it was uplifted more evenly and 

 afterwards tilted gently westward ; and, though the evidence cited indicates 

 greater deformation of the ancient strand-line than the writer formerly 

 supposed had occurred (Cotton, 1912), this deformation is slight as compared 

 with that in the Port Nicholson area. 



It may be inferred, first, that the land west of the Port Nicholson 

 depression was uplifted with only slight deformation while Port Nichol- 

 son was sinking, the two areas being connected by a warped strip ; or, 

 secondly, that the two areas represent blocks moving qu'te independently 

 (though at the coast-line there is no recognizable fault-scarp separating 

 them) ; or, thirdly, that the uplift which raised the platforms on the west 

 affected the whole district nearly evenly, and that in the Port Nicholson 

 area the uplifted platforms have been resubmerged by more recent warping 



