404 MAJOR A. E. DWEEEYHOTTSE ON THE [vol. lxxix, 



Slievenaglogh, Slieve Bearnagh (2394 feet), Slieve Meelmore, and 

 others ; and that this rampart was overridden from the north is 

 shown by the enormous accumulations of glacial deposits in the 

 Silent Valley and the valley of the Annalong River on the south. 

 These deposits consist very largely of granitic debris, but occasional 

 boulders of Silurian grits and altered slates also occur. 



The mountain-tract is divided into two portions by the pass 

 which carries the road from Hilltown to Kilkeel by way of the 

 Deers Meadow, and the fact that the northern ice flowed over this 

 pass is indicated by the striated surfaces and by the transport of 

 thousands of boulders of the altered Silurian rocks (banded horn- 

 stones, etc.) of the Deers Meadow southwards through the narrow 

 valley between Slievemuck and Pigeon Rock Mountain. The 

 .highest point of the pass is 1225 feet ; but that the ice stood at a 

 much higher level than this is shown by the striae on the southern 

 spur of Pigeon Rock Mountain at 1500 feet, and the granite- 

 boulders on the summit of Slievemoughanmore already mentioned. 



To what extenb the Mourne Mountains were overridden by the 

 ^subsequent western glaciation is a much more difficult matter to 

 decide. On Castle Bog, between Tievedockeragh and Eagle 

 Mountain, I found several pebbles of flint in sandy drift beneath 

 peat at about 1100 feet; but these might obviously have been 

 •carried by either the- Scottish or the western ice, though a well- 

 marked overflow-channel known as The Windy Gap, at about 

 1300 feet (between Slievemoughanmore and Eagle Mountain, and 

 falling south-eastwards), might be taken as an indication of an 

 ice-movement from the north-west. 



About 4 miles south-west of The Windy Gap is another 

 overflow-channel on the northern flank of Slievemee at about 1200 

 feet, and this also falls in a south-easterly direction ; while on 

 Finlievemore at 1300 feet are stria? pointing south-eastwards. 



Near the summit of the col south of Slievemee are two parallel 

 crescentic moraines at a height of 1000 feet. They are convex 

 towards the south-east, and were doubtless the product of an 

 ice-lobe pushing its way over the col from the north-west. 



It is thus clearly shown that ice passed over the south-western 

 part of the Mourne Mountains from a north-westerly direction ; but 

 it must be borne in mind that this may have be£n a portion of the 

 Scottish flow escaping from the enormous pressures in the rapidly- 

 narrowing triangular area on the west which has already been 

 described. 



I have been unable to find any undoubted Tyrone rocks at high 

 levels in the Mourne Mountains, and, until such are forthcoming, 

 the invasion of the group by the western ice must be a matter of 

 conjecture. 



That the ice from the Tyrone area flowed along the northern 

 face of the Mourne Mountains is indicated by the direction of the 

 strise at 500 feet O.D. on the north side of Loughanlea Hill, at 

 700 feet at Eofanny Plantation on the southern flank of Craiga- 

 lusta and on the northern slope of Slievenaman, at 650 feet on 



