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Proceedings of the Royal Irish Academy. 



following it westward to the sea, and northward along the coast 

 between Portnafrankanagh and Scotch Port Rock, its massive character 

 is well observed, as well as the manner in which remnants of the 

 dark-gray mica-schist — here almost absorbed — lie between thick 

 bands, and are moulded over great lenticular liummocks of the 

 intruded mass. Southward of the area of gneiss, the peninsula, as far 

 as the newer gray granite of Termon Hill at Black sod Point, is formed 

 of knotted, silvery mica-schist, which seems to be the lowest portion 

 of the metamorpliic series, strati graphically speaking, here to be seen. 



Opposite this on the mainland, another important projection of 

 quartzite from the Corslieve range occurs, at the outskirt of which, 

 and separating it from the mica-schist area, runs the boundary in a 

 zig-zag course, marked as usual with a band of limestone, which 

 appears here and there through the almost continuous peat-covering. 

 So continuous is the covering on the north side of the projection that 

 the position of the boundary line can only be conjectured. 



Passing another such, but smaller, projection from the range, we 

 may cross to Achill Island, where the divisional zone between the 

 two great groups is to be seen at four points. 



A band of mica-schist strikes south-westward through Corraun- 

 Achill, leaving high quartzite hills on the east in this peninsula, and 

 a quartzite area on the north-west, fringed by limestone. It crosses 

 Achill Sound, to be followed in a narrow valley to Ashleam Bay, 

 near the soutliern extremity of the island. The mica-schist, which is 

 dark-gray, and contains a graphitic seam and coarse sheared grit, dips 

 south-eastward under quartzite, a pebbly band intervening ; and on 

 the north-west side of the bay the schist dips away from quartzite 

 which forms the hill on that side, a pebble -bed here also intervening. 

 There can be little question that the schist is the summit of an 

 anticlinal fold, as shown in the accompanying section. 



Fig. G. — Section across valley near Ashleam Bay, showing quartzite {q) with 

 pebbly grits on either side, micaceous and graphitic schists, and coarse 

 dark-gray grit beds between : also mica-schist (w) faulted up against 

 corresponding rocks south of the central hill. 



The quartzite on the south-east side forms a ridge, to the south of 

 which the mica- schists again appear, much dislocated and doubly 



