Wright and Muff — Pre-glacial Raised Beach. 255 



about 10 feet high stands on the raised-shore platform, and 



exhibits the following section : — 



Feet. 



Boulder-clay, . . . . . . 4 



Lower head, . . . . . . 5 



Black sand and pebbles (of slate and 



quartz) in lines, . . . . . . 1-2 



Platform. 



It now stands about 5 yards from the cliff, and shows that 

 at one time the drifts covered a considerably larger extent of 

 platform than at present (see Plate XXIII.). 



It is worth noting in this connexion how seldom any erosion 

 of the drifts is effected by the waves. Vegetation often obscures 

 the cliff to its very base, and even spreads out on the platform, 

 which is always overgrown by lichens (see Plate XXVI.) . It 

 seems to be swept by waves only at high tide during storms with 

 an on-shore wind. 



The superposition of the boulder-clay proves the pre-glacial 

 age of the lower head and raised beach. The lower head, in its 

 turn, marks a period before the oncoming of the ice, when debris 

 from the old sea-cliff accumulated on the beach, after it had 

 been raised above the reach of the waves. The occurrence of 

 blown sand close down to the rock-platform indicates that eleva- 

 tion commenced before the head began to accumulate. 



Three-quarters of a mile to the east of the section just 

 described, where a road descends on to the shore, the section in 



the cliffs is as under : — 



Feet. 



Boulder-clay, . . . . . . . . 26 



Sand and gravel, . . . . 7^- 



Rock-platform. 



At the base, and resting on the platform, there is a thickness 

 of 3 feet of coarse gravel, which is succeeded by beds of fine and 

 coarse sand, with layers of well-rolled pebbles. Not only is the 

 sand sifted into beds of different degrees of coarseness, but the 

 pebbles are fairly well sorted into sizes. A few pebbles of distant 

 origin were picked out of the gravel (see p. 261). 



The boulder-clay is of a greyish colour, and contains numerous 

 small pieoes of slate as well as larger striated stones, all of which 



