294 Transactions. 



sufficient magnitude to bring about sudden marked increase in the supply 

 of^waste can have taken place.* 



1(2.) Since there is other evidence that uplift of small amount has very 

 recently taken place, it is worth while considering its efficiency as a cause 

 of progradation. Rapid uplift, even of small amount, seems to be capable 

 of producing the result if the profile of the neighbouring sea-floor was 

 graded before the movement took place. Slight shallowing of the sea 

 would disturb the equilibrium, .subjecting the off-shore deposits to a some- 

 what stronger wave-action than formerly, and therefore causing them to 

 be reworked and the finer material to go into suspension. Meanwhile 

 the Clarence and the other smaller rivers would continue to pour oiit their 

 enormous load of waste, the bulk of which would be slightly increased by 

 rejuvenation following the small uplift. The balance previously existing 

 between the supply of waste and the transporting-power of waves and 

 currents having been in this way disturbed, some of the surplus waste 

 would be thrown up along the shore, covering over the rock platforms of 

 the uplifted coast. A similar coastal strip of flat land at the mouth of the 

 Waipara River, in North Canterbury, has also been explained by Speight-f- 

 as the result of uplift. 



It would seem that, in the case of the Marlborough Strand-plain, after 

 the off-shore profile has become graded with respect to the present level 

 of the sea, and waves and currents are again able to dispose of the waste 

 supplied, the attack of the waves on the shore will probably again become 

 energetic, the strand-plain will be cut away, and the cliffs at its rear will 

 again begin to recede. It is, indeed, possible that progradation has taken 

 place many times in the recent past, continuing for a brief period after 

 each small movement of uplift. 



Art. XLI. — Supplementary Notes on Wellington Physiography. 



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

 [Read before the Wellington Philosophical Society, 22nd October, 1913.] 



Fault-line Valleys. 



On the map{ accompanying my former " Notes on Wellington Physio- 

 graphy " the Wellington fault is indicated as ending south-westward in the 

 valley of the Tinakori Stream. This is the end of the fault-scarp, and 

 therefore the end of the line upon which recent movement took place. 

 There is, however, evidence of extensive earlier faulting in the form of a 

 broad zone of crushed rock at the head of the Tinakori Stream and on 

 the divide between it and the Kaiwarra, and farther on there is such an 

 exact alignment of the Upper Kaiwarra and Silver Stream Valleys with the 

 Tinakori Stream and with the Wellington fault-scarp that I am now con- 

 vinced that all these features constitute a single lineament. 



* R, Speight, however, considers that Canterbury streams indicate that " a maxi- 

 mum of erosion [due to a climatic cause] is past, and another cycle of deposition has 

 commenced." (Trans. N.Z. Inst., vol. 43 (1911), p. 410.) 



t R. Speight, Trans. N.Z. Inst., vol. 44 (1912), pp. 224-25. 



t Trans. N.Z. Inst,, vol. 44 (1912), fig. 2, p. 247. 





