Cotton. — Warped Land-surface at Port Nicholson. 139 



of small ravines only are passed, and these hang above the shore-line as 

 a result of cliff -re cession that has recently been in progress. Slight sub- 

 mergence produces no noticeable effect on the mouths of hanging valleys 

 such as these, and so the exact position of the hinge-line of tilting cannot 

 be ascertained from them. Farther on, however, Gollan's Valley and the 

 valley of a small stream debouching close to Pencarrow Head are drowned 

 to such an extent as to indicate very considerable submergence (fig. 2, and 

 Plate XXXI, fig. 2). 



Gollan's Valley is fairly large, heading eight miles inland, but the other 

 is only two miles long. The streams in both are of such size, however, 

 that it may be supposed that they reached the sea at grade prior to 

 submergence. It is clear that both, when first drowned, were occupied 

 by winding lanes of sea-water, the one three miles and the other rather 

 more than a mile in length. These bays are now cut off from the sea and 

 converted into fresh-water lakes by gravel bars 20 ft. in height above sea-level 

 and accordant with the pre-1855 storm-beach ridge, which is well developed 

 along the neighbouring shore-line in Fitzroy Bay. At the western end of 

 each bar the outflowing water has opened a channel through the gravel. 



The enclosed bays are much reduced in size by the growth of swampy 

 deltas at their heads, and the length of the two lakes which now occupy 

 their lower parts (Koangatera in Gollan's Valley and Koangapiripiri in the 

 other) is thus reduced to about half a mile in each case. The upper part 

 of Gollan's Valley is also thickly aggraded with alluvium. Near the mouths 

 the sides of both valleys are cliffed, and out-jutting points are strongly 

 truncated (Plate XXXI, fig. 2). The cliffs reach a height of 100 ft, on 

 the shores of Koangatera and 50 ft. around Koangapiripiri, and they are 

 evidently the work of waves at a time when the bays were still deep and 

 open to the ocean. For a mile up the somewhat winding Gollan's Valley 

 the swampy delta is bordered, however, by low wave-cut cliffs. These 

 must be .the work of waves raised on the narrow landlocked waters, and 

 their presence indicates a long period of still-stand prior to 1855, for the 

 relative levels of sea and land were constant long enough not only for the 

 development of distinct cliffs (though on mature hill-slopes of weathered 

 rocks, it is true) by waves with a fetch of no more than a few hundred yards, 

 but also for the delta-front to advance for quite a mile past the farthest 

 inland point where cliffs are traceable. This indicates that the uplift of 

 1855 was either the precursor of a new series of earth-movements or was 

 an isolated phenomenon ; and the shore-line features at the western side 

 of the entrance to Port Nicholson lend support to this view. 



As the writer has shown elsewhere (Cotton, 1921), this is a matter 

 of great practical importance. If movements like that of 1855 had been 

 common in the immediate past the outlook for the future safety of the 

 city of Wellington and the continued usefulness of its harbour would be 

 rather poor ; for it must be remembered that the cause of the disastrous 

 earthquake of 1855 was directly connected with the uplift which then 

 occurred, and also that the harbour was made fully 5 ft. shallower by the 

 same movement. As it is clear from what has been stated above that the 

 1855 movement was the first of its kind in this district for thousands of 

 years, the outlook for Wellington is distinctly hopeful. 



A rough indication of the measure of the submergence shewn by the 

 drowning of the valleys to form the bays now occupied by the lakes 

 Koangatera and Koangapiripiri can be obtained by comparing the widths 

 of the mouths of the embayments with the widths of similar but unsub- 

 merged vallevs in the district at various heights above the floor, and also 



