7 20 Proceedings of the Royal Irish Academy. 



as the White Sea. On its floor was deposited a laminated clay containing 

 the shell Yoldia arctica, a species characteristic of that deposit. 



As southern Denmark does not appear to have been involved in this 

 movement of the earth's crust, the presumption is that the subsidence was 

 not of regional dimensions. Scotland, however, appears to have participated 

 in this depression, for marine clays containing distinctly northern shells 

 in situ have been found at some distance above sea-level round the Scottish 

 coast. But we have no evidence that other parts of the British Isles sank 

 below their present level. 



Following the period of subsidence during which the Yoldia Sea was 

 formed, a general elevation of the lithosphere took place in the northern part 

 of our hemisphere. The recently submerged land slowly rose again; the 

 floors of the Cattegat and the Belts became dry land, and the Baltic area 

 became converted into an immense fresh-water lake, known as the Ancylus 

 Lake. A considerable amount of new land was thus won from the sea and 

 added to the European Continent, and on the land surface thus recovered 

 peat-mosses and forests flourished. In a subsequent sinking of the crust, 

 these became submerged, and traces of submarine bogs and forests, belonging- 

 to this period, are of very common occurrence, fringing the existing coasts of 

 northern Europe. 



" In the Baltic area itself, at Falsterbo, a peat deposit with oak and 

 hazel has been found at a depth of 100 feet. Submerged peat and submerged 

 kitchen-middens with neolithic remains have been found on the western 

 coast of Denmark, 1 and at several points round the coasts of the British 

 Islands and the north of France similar indications of a recent subsidence 

 are to be seen. From the positions in which peat in situ has been found 

 round the coast of Britain, it is inferred that the land stood at least 

 60 or 70 feet above its present level, and probably very much more. The 

 map of Ireland (Plate V), giving the localities at which submerged peat has 

 been observed round the coast, shows that this country, too, sank in recent 

 times considerably below its former level. That the depression took place at 

 a period prior to the formation of the lowest raised beach is proved by the 

 succession seen on the shore near Portrush, and again on the shore to the 

 south-east of Wexford. In these localities submerged peat underlies marine 

 deposits which are now some feet above the level of high tide." 2 



Quite recently peat containing stems and roots of trees, seeds, leaves, 



1 Nils Olof Hoist " Kvartar-studier i Danmaik ouh norra Tyksland," Geol. Foren,Forahndl. Bd. 

 26, p. 433 etseq. 



- " The Geology of Clare Island, Co. Mayo." Mem. Geol. Survey of Ireland (1914), p. 41. 



