760 SIE HENRY H. HOWORTH ON THE [NoV, 9, 



materially altered in position since they were deposited, for 

 although in the recessed portions of the various bays on the 

 south coast the non-occurrence of raised beaches probably proves 

 that their continuity has been broken at many places, yet their 

 occurrence on the headlands shows that substantially the coast- 

 line remains where it was when they were laid down, while the 

 raised beach on the Thatcher Bock in Torbay is another palpable 

 evidence of the same fact. 



As I have said above, there is at present no reliable evidence 

 that the relative level of land and water on our shores has altered 

 since the Christian era, and it would seem almost certain that all 

 our true raised beaches — that is, those which represent old beach- 

 surfaces and not mere deposits of pebbles and shells by high tides 

 — are older than Roman times. They may be of different ages, 

 but the persistence of one very notable raised beach at a level 

 of 20 to 40 feet in Scotland seems to point to one particular 

 upheaval having a wider range than could be caused by merely 

 local causes, while the quiescence of the level since the Christian 

 era seems to support the view that the upheaval was rapid 

 and cataclysmic in Britain, as I have ti-ied to show it was in 

 Scandinavia. 



The discovery of a number of dug-out boats of a very primitive 

 type in connection with the raised beaches of the Clyde pro- 

 bably points to the relative date of the upheaval as having been 

 in what is called the Neolithic age. A similar inference may 

 perhaps be drawn from the finding of flint tools in connection 

 with the raised beaches in the Isle of Man, in regard to which my 

 friend Mr. Lamplugh writes : — " We gain a valuable clue to the 

 approximate age of this beach in the presence of Neolithic 

 chipped flints on its surface in places. The shingle seems to have 

 been resorted to by the inhabitants for the sake of its pebbles of 

 flint derived from the drift, which have sometimes been struck 

 into flakes on the spot. ... I found in the outer part of the beach 

 a single artificial flake which had been partially worn down by 

 marine attrition, and mxTst therefore have been in existence as a 

 flake during the accumulation of this portion of the beach. 

 Between Hue Point and Blue Point I found these chips, in one 

 place, in the blown sand covering the inner part of the old shore. 

 These facts denote that at any i-ate part of the platform was in 

 existence in Neolithic times, but that it may not have attained its 

 full breadth until after the close of that period " (Survey Mem. 

 Isle of Man, p. 403). 



Let us now turn to the mollusca of the raised beaches. A 

 monograph on the raised beaches of the southern coast was 

 published by Prestwich in the Q. J. Geol. Soc. xlviii. p. 263. In 

 this paper he gives several lists of shells found in them. In one 

 case only does Mya arenaria occur, although the shell is such a 

 common living shell in the Channel, namely on the Thatcher Rock 

 in Torbay, which has a peculiar history and is probably much 

 older than the other raised beaches of the Channel: Pengelly 



