QUATERNARY DEPOSITS OF BRITISH ISLES BROOKS. 333 



necting former islands with the mainland; the neck of the Hill of 

 Howth is a notable example. Reference is made to these raised 

 beaches in many of the Geological Survey Memoirs dealing with 

 maritime districts. The 25- foot beach attains its greatest height 

 at Malin Head, where it is about 33 feet above high-water mark; 

 north of Londonderry it stands at 32 feet, in Lough Foyle and along 

 the coast of Derry and Antrim about 25 feet. In sheets 20, 21, 28, 

 and 29 the maximum height attained seems to be 15 to 20 feet, includ- 

 ing the well-known bed at Larne. At about this height well-marked, 

 shelly, raised beaches extend down the east coast ; at Dublin, the level 

 is 10 to 15 feet, and in the Counties of Wicklow and Wexford it 

 ranges from 12 to 6 feet, very conspicuous in places. 



On the south coast we have no mention of a postglacial raised 

 beach except at Cork, where in the quieter channels a grass-grown 

 flat backed by an old cliff a few feet above present high-water mark 

 may represent this feature. On the flat occur kitchen middens. The 

 only points on the west coast where any vestige of a raised beach is 

 seen are Drumcliff Bay, near Carney, County Sligo, where a beach- 

 like bed 6 to 7 feet above high-water mark contains remains of 

 oysters, clams, and periwinkles (Memoir sheets 42 and 43, 1885), and 

 near Sligo (Memoir sheet 55) , where a " silty bed containing cockles " 

 lies appreciably above high-water mark; and the middle island of 

 Aran, where a shell-bearing beach is recorded by Kinahan, and at 

 the mouth of the Kenmare River, in County Kerry, where there is 

 a thin bed of oysters and other shells just above high-water mark 

 (Memoir sheets 182, 183, and 190). There is thus a striking decrease 

 in the height of this beach from northeast to southwest. 



The molhiscan fauna of the 25-foot beach of northeast Ireland has 

 been studied by Mr. Lloyd Praeger (1896) ; he finds a complete ab- 

 sence of arctic species, and only three of northern type, while nine 

 species are of marked southern type. In the present seas of the dis- 

 trict the numbers are four northern and three southern. This indi- 

 cates that the climate was somewhat warmer than the present, instead 

 of being colder, as it was when the higher beaches were formed. 



Below the level of the 25-foot beach in northeast Ireland are 

 numerous other beach terraces extending down to high-water mark. 

 Among these a 15-foot beach is often distinguished; in fauna and 

 general characters it is not very different from the 25-foot beach and 

 is probably very little later. Kinahan (1878) supposed it to be 

 separated from the latter by a 30 to 40 foot elevation, and referred 

 the Kilroot gravels to the 15-foot beach, since they contain imple- 

 ments considered by Mr. Du Noyer as younger than those from 

 Magheramorne and Larne. In the river valleys the 25-foot beach 

 is often continued as a gravel terrace 25 feet above the present level 

 of the water, and evidently due to the same submergence. By anal- 



