part 3] GLAC'IATION OF XORTH-EASTERN IRELAND. 379 



The Cookstown and Dungannon Area. 



This area, especially in its southern part, is characterized by 

 enormous moraines, which are considered to be frontal moraines 

 produced by the western ice during the period of its final retreat. 

 There are also extensive spreads of current-bedded sands and gravels. 



A large sand-pit in the town of Coalisland shows a deep section 

 in stratified sands and gravels, which are somewhat contorted. The 

 pebbles and boulders include schist, flint, burnt flint, red sandstone, 

 basalt, chalk, Carboniferous Limestone, epidiorite (Tyrone Axis), 

 and granites, also boulders of white Lough-Neagh Clays, with 

 numerous masses of silicified wood derived from the same deposit. 



Dungannon stands on one of the great series of moraines above 

 mentioned, and at the Tyrone Brickworks (about a mile and a half 

 north of the town) is a section that shows blue and red boulder- 

 clay overlying red stratified clay and sand which contain ironstone- 

 nodules and lignite from the Lough-Neagh Clays, the outcrop of 

 which lies east of the section. 



The boulder-clay contains much Carboniferous shale (local), big 

 and well-striated boulders of Carboniferous Limestone, Tyrone 

 diorites and epidiorites, schist and granites, and a porphyrite from 

 the same region on the west. The lower deposit of stratified sand 

 and clay, with its material derived from the Lough-Neagh Clays 

 on the north-east, appears to be a relic of the glaciation by the 

 Scottish ice ; while the boulder-clay above was undoubtedly pro- 

 duced by the later flow from the west. 



West of Dungannon, as the hilly country is approached, the 

 moraines become still more conspicuous, the largest in the district 

 being that running through Mullaghbane (2g miles south of 

 Castlecaulfield), Castlecaulfield, and Donaghraore, to the neighbour- 

 hood of Cookstown. West of this line the moraines can be seen, 

 rank behind rank, for several miles. They consist almost entirely 

 of material from the west ; but at several localities, as, for example, 

 in a quarry opposite the castle at Castlecaulfield, a purplish boulder- 

 clay contains, in addition to the western rocks, numerous pebbles 

 of flint which can only have been derived from the country on 

 the north-east, again indicating the passage of the Scottish ice 

 over this area. Numerous angular boulders of basalt, similar to 

 the Tertiary rocks of the Antrim Plateau, also occur in this pit ; 

 but their angularity indicates, in all probability, their origin from 

 some local dyke. 



The Country south of Lough Neagh. 



South and south-west of Lough Neagh is a large tract of land 

 lying below the 100-foot contour, and occupied by peaty and 

 swampy flats. From the peaty flats emerge many drumlin-like 

 masses of glacial deposits, chiefly boulder-ckny, but with patches of 

 morainic gravels, as at Hunts CorneiyMaghery, and Charlestown. 



When examined on the ground, these mounds are seen to possess 

 a roughly linear arrangement, the lines running approximately 



