5 



with a great assemblage of boulders, the latter having been 

 left, whilst the finer material has been washed away. These 

 boulders are especially numerous in the protected cove at the 

 back of the Bluff at a distance of about half a mile from the 

 latter. Here there are hundreds of large erratics between 

 tide-marks and also on land at or near the base of the 

 moraine cliffs (plates vii., viii., and ix.). By far the greater 

 number of these are granitic and chiefly of the local type. 

 There are, however, other granites and some sedimentary 

 rocks represented which are not local. Very siliceous quartzites 

 occur among the erratics. On the beach near high water-mark 

 three masses of quartzites lie in close proximity to one another, 

 measuring respectively 8 ft., 6 ft., and 4 ft. in their longer 

 diameters. One large quartzite between tides has attached 

 to it a bed of brecciated marble 1 ft. in thickness. One 

 boulder of fine-grained, pink-coloured granite 3 ft. in length 

 is highly glaciated and polished. Some of the granites are 

 of exceptional size. One of these, on the beach, which is fall- 

 ing apart along joint-planes, measures 23 ft. in length (plate 

 ix.). These beach erratics are most plentiful opposite to the 

 old cliffs where the sea has encroached on the moraine, and 

 for a distance of half a mile of coast they are in countless 

 numbers. 



A suggestion might be made by some that these boul- 

 ders, which are mostly granite, were worn from the Bluff in 

 the ordinary course of subaerial waste, and subsequently 

 transported along the beach by wave action. The evidence, 

 however, does not favour this view. It would follow as a 

 natural order of things that the ice-sheet in passing over the 

 granitic ridge (of which only isolated fragments remain in 

 the headlands and islands) would quarry the stone and carry 

 it forward. The immense quantity of this granite, which is 

 spread over hundreds of square miles of the inland districts, 

 is sufficient evidence of this : but the presence on the beach 

 of numerous stones foreign to the locality indicates the work 

 of an agent more far-reaching than wave action. Neither 

 can we assume that the granite boulders have been derived 

 from granite dykes penetrating the schists on which many 

 of them rest. The schists, except in a narrow zone where 

 they form a junction with the granite, are quite free from 

 granitic intrusions. Moreover, if we refer the beach boulders 

 to ordinary local waste and transport, there ought to be a 

 long train of these stones, most numerous at the base of the 

 Bluff and gradually thinning off with distance from this 

 source. It is, however, not so. Between the Bluff and the 

 great 'field of beach erratics there is half a mile of coast along 

 which granite boulders scarcely occur, whilst the greatest 



