TEANSACTIONS OP SECTION J. 487 



the water was quite clear, but as every wave curled over to 

 break I saw that it was discoloured with sand, which the 

 strong shore-current carried towards the north. These waves, 

 which were 8ft. high, were breaking in about 18ft. of water. 



Some people think that a rocky headland projecting far 

 out to sea must stop the travel of sand and shingle. I do not 

 think this is the case ; it may, and sometimes does, stop the 

 shingle, but the saud travels round it. The obstruction often 

 keeps the shingle and coarser sand in a bay formed by its 

 base, where it remains until it is ground to fine sand, in 

 which condition it is able to travel round the obstructing 

 headland. 



At the projecting end of such headlands the waves dash 

 with violence against the rocks and the steep shore, disturbing 

 the bottom to considerable depths, thus keeping the sand 

 "alive;" and the shore-current, which nothing checks, carries 

 it round the rocks, at the same time filling all quiet bays and 

 recesses in them. 



In positions where the supply of shingle is great, and the 

 waves act at a favourable angle, the shingle-beach is able to 

 advance so as to surround the headland, in which case it must 

 follow that the water in front of the headland is sufficiently 

 shoaled to allow the shingle to travel. 



Dunedin and Banks Peninsulas are cases where only sand 

 can travel round the headland, and, the distance being great, 

 and the water deep, it may be inferred that only very fine sand 

 can travel round. Cape Foulwind is a case where coarse sand 

 and very fine shingle are able to get round the rocks. The bluff 

 of Napier and Point Elizabeth are cases where shingle travels 

 round them. 



Thus a succession of projecting headlands at a distance 

 from the source of supply of the shingle may completely stop 

 it, as it is either all ground to sand before it can reach the ob- 

 struction, or, having reached it, it is detained in a hollow 

 bight at the base of the headland, where it is exposed to the 

 grinding action of the waves until it is reduced to sand, which, 

 as it is formed, is sifted from the shingle, and carried on its 

 travels. Should, however, the sand be too coarse to travel in 

 the depth of water existing at the rocky point, it is cast ashore 

 in the coves and bays, and there further " treated " until it has 

 acquired the requisite fineness for locomotion in the required 

 depth of water. 



Were it not for the constant supply of fresh material to be 

 acted upon, the sea would wear the land away with alarming 

 rapidity. The hardest rocks where exposed to be scrubbed by 

 the waves are worn away in a very short time, but usually the 

 rocks are protected at foot by small beaches of shingle or sand, 

 constantly renewed. 



