part 3] GLACIATION OF NORTH-EASTERN IRELAND. 391 



situation. This is covered with a thick deposit of peat, and, if 

 this were removed, the col would be below the level of The Murder 

 Hole. 



At Macosquin the drift is thin, the basalt coming to the surface 

 in man} r places. In a thin gravel consisting chiefly of basalt 

 I found a pebble of Ailsa Craig eurite, and one of gabbro from 

 the Tyrone Axis. 



A quarter of a mile north-east of Macosquin, near Coleraine, lies 

 a mound of stratified gravel containing basalt, schist, quartzite, 

 and a fine-grained granite, and 1 mile from Macosquin on the 

 same road are two channels falling southwards. . The Blackburn 

 occupies the eastern one, flowing from an open peaty flat on the 

 north, through the narrow valley at Blackburn Bridge, into the 

 open valley of the Macosquin Biver. 



In the sandpits near Coleraine Station the following rocks 

 occur : — diorite, hornblende-granite, syenite, red granite, red 

 quartz-porph} r ry, and mica-schist, all from the Tyrone Axis, also 

 Ailsa Craig eurite, several varieties of pink granite (probably 

 Scottish), and chalk and flint. The two last-named constituents 

 are present in large quantity, and were derived from the neigh- 

 bourhood of Bortrush on the north. 



Near Macfin Station, 5 miles south-east of Coleraine, and on 

 the bank of the Biver Bann, is a gravel-pit in which the following 

 section is exposed : — 



Tlxiclmess in feet. 



Horizontally stratified yellow sands 6 



Gravel 4 



Fine sandy gravel, strongly current-bedded, with 



many pebbles of basalt (base not exposed) ... 15 



The current-bedding dips in a direction varying from east to 

 south-east. 



In addition to the basalt which forms the bulk of the gravelly 

 material, pink hornblende-granite, coarse red muscovite-granite, 

 mica-schist, red sandstone, Silurian grit, vein-quartz, iron-ore 

 (Tertiary), burnt flint, banded chalcedony, flint, and Ailsa-Craig 

 eurite occur. All these rocks are such as could be derived from 

 the north-east or north, there are no big boulders, and the materials 

 are all water-borne. 



The floor of the gravel-pit is some 50 feet above the level of the 

 river, and forms part of a steep bank. The top of the deposit is 

 flat, and defines a terrace which is continued on the opposite bank 

 of the Bann. It should be noted that the valley of the Bann 

 narrows suddenly at this point, half a mile below the railway 

 viaduct, and that this narrowing coincides with the first appear- 

 ance of a typically northern drift. I consider this terrace to be 

 an outwash fan from the Scottish ice, at a time when the morainic 

 deposits of Drummaquill, Bally money, and Armoy (previously 

 described) were being laid down. 



Q. J. G. S. No. 315. 2 e 



