ChaelesWORTH — Glacial Geology of Norlh-West of Irclnnd. 215 



all sizes, plucked from the granite hills of the south. As already sliown, they 

 ascend the great Errigal, Muckish, and Crocknafarragh quartzite range, almost 

 to its liighest point, and must have passed not only through tlie larger and 

 deeper gaps bnt also clean over the high level cols, wliere they occur in very 

 gi'eat numbers. 



Tliey rest on the summit of t'ue diorite ridges of Derryreel and Croagh- 

 losky, and on the quartzite hill of Tievealehid. They are extraordinarily 

 numerous along the coastal strip extending from Ijloodv Foreland to Falcarragh. 

 Jioulders of granite, coarse and finely crystalline, distinctly banded, and of all 

 sizes (up to (S feet in lengtli)are strewn in great abundance along the lulls to 

 the south of Sessiagh Lough. 'J'hey are common over all the Dunfanaghy area, 

 and are seatteied over the Horn i)eninsula in great numbers and range up 

 to 7 feet in diameter. 'J'lie larger boulders not infrequently exhibit the typical 

 glacial form ; the smaller ones, on the other hand, are usually well rounded. 

 They are extremely abundant along the shore to the east of Horn Bridge and 

 along the southern part of the peninsula, decreasing apparently in numbers, 

 as traced northwards across the latter, becoming comparatively rare towards 

 Horn Head and the northern coast. 



The erratics of the Crocknakilla '•' felstone-porphyry " have a similar 

 disT.ribution, occurring at Faugher, Dunfanaghy, and Horn peninsula. No 

 boulders of this rock were observed to the south of the outcrops. 



Boulders of granite everywhere dot the surface of the Clonmass and Ards- 

 peninsulas (up to 9 feet in length). They are very abundant and large over 

 all the country south of Carrigart and at Carrigart itself, while they are 

 especially large and angular at Ballyness. They also occur in liosguill, e.g. 

 to the east of Ko.5apenna. In Mulioy ]5ay they are very few. 



These granite erratics first begin to pass off the eastern margin of the 

 granite in the neighbourhood of Garton Lough, where boulders up to 10 feet in 

 diameter rest on the schist. Great numbers lie scattered over the surface at 

 Losset Beg, and were traced in diminishing numbers from here northwards 

 to Coldrum, where they occur sporadically. At Stragaddy the granite 

 boulders are extremely numerous and of good size. They are also 

 present in the vicinity of Lough Greenan, while an occasional boulder 

 was noted near Kilmacrenan Station (4 feet in length). They also occur in 

 places round the shores of Lough Keel and on the surface of the country near 

 this lake.^ Very few boulders were met with in the southern half of Mulroy 

 Bay, though east of Gortnaclere and Springfield they again make their 

 appearance in appreciable numbers, whence northwards and westwards they 



1 At " B " of " Ballyscanlor " of the one-inch O.S. map occurs a huge granite erratic, 

 ca. 13 feet long, its other dimensions in uroportion. 



