66 Guide to Belfast. 



wliich they referred to the fluviatile genus Unio. These 

 shells have been more recently dug out by Mr. Swanston 

 in 1878 from Crumlin river beds, and found to be the 

 common Mytilus edulis} These occur in a dark blue mass 

 of clay, which rests on true boulder clay, with numerous 

 erratics derived from the boulder clay ; hence the clays 

 cannot be earlier than the Glacial period. The Afytilus 

 beds point to the fact that the whole of the area was con- 

 nected with the sea at some period subsequent to the Glacial 

 period. A further point of interest is that, recently, the 

 shrimp Mysls relida has been taken living in the depths of 

 the present lough. That the river systems of the country 

 had been established before the subsidence which is now 

 occupied by the lake, is suggested by the fact that a well- 

 defined channel can be traced on the bed of the lake 

 following the course that would have been taken by the 

 Bann river before the subsidence of the ground at this 

 portion of its course. From these evidences we are there- 

 fore led to conclude that the lake had its origin subsequent 

 to the Glacial period. Popular tradition places it in the 

 Human period, and it may not be improbable that the 

 tradition is altogether without foundation. (See Sir Archi- 

 bald Geikie's Ancient Volcanoes of Great Britaiti, vol. ii, 

 page 448, et seq.) Silicified wood is found along the shores 

 of Lough Neagh. Local peasantry attribute petrifying 

 qualities to the waters of the lough; but as the silicified 

 wood in question is found also in the boulder clays to the 

 south and east of Lough Neagh, it would appear that speci- 

 mens found on the shore have been derived from these beds, 

 which, in turn, had found their supplies from deposits of the 

 same age as the lignites of Ballintoy. Silicified wood has 

 also been found in boulder clays at Armagh, indicating an 

 abundant forest from which such widespread erratics have 

 been derived. 



The only other lakes calling for mention in the county of 

 Antrim are Lough Mourne, four miles north of Carrickfergus, 

 and Lough-a-veema, six miles by road, north-west of 

 Cushendun. This latter lake is of interest from the 



1 Geological Magasine, February, 1879. 



