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renewals, when, moreover, small glaciers existed in the higher 

 portions of the valleys. 



DEDUCTIONS FROM THE FOREGOING. 



When we consider the successive stages of glaciation, we 

 are led to the inquiries, why they occurred, why the centres of 

 accumulation changed, and why the movements of the ice-sheet 

 were so diverse. We owe to Mr. G. W. Lamplugh, I think, the 

 suggestion which points to a satisfactory solution. Starting with 

 an ice-cap in Scandanavia, the moisture laden winds from the 

 Atlantic would part with their burden in meeting the cold heights, 

 and tend ever to increase the accumulation on the west side of the 

 latter. This occasioned a very great accumulation in these 

 islands, first in Scotland, which sent its sheet in over the Antrim 

 coast, west by south, effecting also a general westerly movement 

 of ice which had collected all over Ulster. 



The accumulation still increasing in its western side, centralized 

 next over the area of the Inner Hebrides ; and in turn sent its 

 tongues southward along the channel and to some extent into 

 the valleys of northern Ulster, depositing there the red shelly 

 Boulder-Clay. 



This seems to have been followed by melting which occasioned 

 the formation of the Bollee gravel and boulder-beds. Although, 

 doubtless, in the higher grounds of Ulster, a new prevailing 

 accumulation was in progress, which culminated in the axis noted 

 by the late Mr. Close. 



SANDS AND GRAVELS. 



Sands and gravels of glacial origin are found widely scattered 

 over the sides of both valleys, and are particularly abundant in the 

 bottom of that of the Roe. Intercalated beds of sand and gravel 

 are noticeable, in the gravelly Boulder-Clay belonging to the third 

 stage ; but these do not demand any special attention here. We 

 shall consider briefly some eskers, moraines, and glacial flood 

 gravels. 



