BEACH AND BOULDERS NEAR BRATJNTON AND CROYDE. 669 



the outside — if the felsite cannot be a harder, more solid fragment 

 of the Bittadon vein — and, further, if they cannot have been derived 

 from known or inferred submarine bosses of rock *, which some 

 believe furnished many of the boulders dredged up on the south 

 coast of Devon and Cornwall ; if the great boulder of red granite 

 on the shore below Saunton Down must be identified with some 

 Scotch rock, and if the block of dark grey felsite should be referred to 

 one of the Arenig porphyries — that is on the hypothesis that these 

 are north-country boulders — must we assume local glacial action 

 to account for their occurrence where we now rind them? and if not, 

 what explanation can we offer of their being found in that district 

 at all ? 



That they owe their present position on the jagged rocks of the 

 coast and under the ancient beach to the action of the waves of a 

 sea at about the same level as at present seems almost certain, 

 because there they lie half buried in the shingle recently thrown up 

 by the sea, and blocks as large are hurled by the waves to much 

 higher levels in many of the creeks and coves around the coast f; 

 but where did the waves pick them up ? 



A glance at the map will show that the district in question is 

 just in the line of advance of the great tongue of ice that crept 

 along the west coast of Scotland and the Lake District, and abutting 

 against the ice-clad coast of North Wales, was held back by it, so 

 that it was forced to turn round by Chester on the east and Anglesey 

 on the west. Part of its terminal moraine ought to be found in the 

 Irish Sea — at any rate, bergs from it must have floated off into the 

 Irish Sea ; and there is nothing improbable in the idea that many a 

 half-melted mass stranded off the coast of Devon and left boulders 

 strewn over the sea-bottom around. That the boulders were not 

 dropped during a period of submergence where now found is shown 

 by our never rinding any masses of drift, but only isolated blocks, 

 and they all look sea-worn. Nor were they carried ashore on bergs, 

 because they are close up to a wall of solid rock where a berg could 

 not have floated them. 



Of course we must not attach any great weight to the fact that 

 they have no glacial markings, as we only see them at all because the 

 waves have washed away the surrounding sand and shingle, and 

 that might have obliterated the striae ; but I think that any one who 

 examines the blocks will allow that it is improbable that such is the 

 explanation of the absence of all traces of ice-action. However, 

 I will not lay much stress on this point. 



Mr. Townshend Hall records some boulders with grooves, though 

 they do not seem to have commended themselves to him as un- 

 doubtedly of glacial origin. If these were striated blocks, they still 



* Smeaton, 'A Narrative of the Building and a Description of the Con- 

 struction ofiihe Eddystone Lighthouse with Stone,' 1813. 



Godwin- Austen, Quart. Journ. Geol. Soc. vol. xi. 1855, p. 532 ; ibid. vol. xii. 

 1856, p. 38. 



PridecMx, Trans. Plymouth Inst. 1860, p. 40. 



Pengelly, Trans. Devon. Assoc. &c. vol. ix. 1877, p. 182. 



t See Carne, Trans. B. Geol. Soc. Cornwall, vol. iii. 1828, p. 222 etseq. 



