Dr. Hull says : — " The origin of Lough Neagh has been a 

 subject of much speculation and of some mystery, because, being 

 older than the glacial epoch, it cannot be referred to glacial 

 agency, and, being situated on deposits other than limestones, 

 it cannot be considered as the result of chemical solution. Its 

 proximity to the old volcanic region of Antrim has naturally 

 led to the inference that it was in some way connected with 

 local sinking of the surface through volcanic agency. It was 

 not, however, till the geological structure of the adjoining 

 districts of Tyrone on one side, and Antrim on the other, had 

 been accurately laid down on the maps of the Geological Survey, 

 that a key to the history of its origin was found ; and Mr. W. 

 E. T. Hardman, one of the officers of the Survey, has very ably 

 applied the results of his examination of the district surrounding 

 that lough to the determination of its mode of formation. Its 

 northern portion is bounded by the miocene basalts of Antrim ; 

 its southern, partly by alluvial tracts, partly by masses of drift 

 resting on pliocene clays, which in turn overlie the triassic or 

 carboniferous strata. Its length from north to south is fifteen 

 miles, and its breadth twelve, giving an area of nearly one 

 hundred and fifty square miles. The general depth is only from 

 20 to 40 feet, gradually increasing towards the northern shore ; 

 and the surface is 48 feet above that of the sea. Mr. Hardman 

 shows that along the southern shores the pliocene clays origin- 

 ally deposited under the waters of the lake rise to a level of 1 20 

 feet above the sea, or 72 feet above the existing surface of the 

 lake, showing how much greater the area of the lake must 

 have been in this direction. 



11 During the progress of the survey it was found that the strata 

 on both sides of the lake are traversed by several large faults 

 ranging in E. N. E. directions. One of these ranges through 

 the basaltic plateau of Antrim by Templepatrick, where the 

 vertical displacement is about 500 feet, the downthrow being 

 on the south side. These faults are later than the basaltic 

 sheets of the miocene age which they displace, and of older 

 date than the pliocene clays, which are not affected by them, 



