TRANSACTIONS OP SECTION J. 483 



I must now fortify the weakest position in this line of 

 argument by showing sufficient reason for assuming that the 

 material drifted up the east coast ultimately passes through 

 Cook Strait. 



The charts show the same range of tide at either end of the 

 strait. At Gape Campbell and Port Underwood spring-tides 

 rise 8ft., and neap-tides 6ft.; at Queen Charlotte Sound, 

 Porirua, and Kapiti, springs 8ft., neaps 6ft. Nevertheless, as 

 the tides come from the south-east, it is fair to suppose that 

 they run through the strait for a longer time, if not with a 

 stronger current, than the return tide flowing from the west to 

 the east, because the tidal wave, the return eddy of which 

 creates the tide on the west coast, is continually retreating 

 away towards the west at the rate of a thousand miles an 

 hour. 



There is about four hours' difference in the time of high 

 water between the east and west sides of Cook Strait, and a very 

 strong current is set up through the strait with the rising tide. 



If any material at all is carried by these currents, it will be 

 carried farthest by the tide which lasts longest, and will be 

 spread and deposited where the current is checked by the open 

 sea — that is, in the great bight between Capes Farewell and 

 Egmont. There can be little doubt that the tide-rips carry 

 great quantities of material from the wear of the land ; other- 

 wise it would be impossible that the extraordinarily deep 

 -channel through that part of the strait where the current is 

 strongest could be prevented from 'silting up to the depth of the 

 banks that surround each entrance. 



I assume, therefore, that the drift -material of the east 

 coast finds its way at last to Cook Strait, and then works its 

 way through to the west by the preponderance of the westerly 

 tidal currents. 



I have thus driven this problem into a corner, and found 

 that all the wear-and-tear of the mountains of the South 

 Island goes to extend New Zealand towards Samoa at its 

 extreme north point. This is a grand deduction, and I hope 

 the critics will make shipwreck of any attempt to dis- 

 prove it. 



But the fact of the shingle and sand travelling continuously 

 in one direction may be disputed, and I must endeavour to set 

 this point on a firm foundation. In the Minutes of Proceedings 

 of the Institution of Civil Engineers there is much writing and 

 discussion on the subject of the travel of material along 

 beaches. It is acknowledged that it does travel, but the extent 

 and causes are the subject of much difference of opinion. Thus, 

 in one of these discussions, Mr. J. T. Harrison, C.E., notices 

 the drift of shingle by the south-east winds which are the pre- 

 vailing winds in that part of the Mediterranean, which drive 



