440 ME. BEilNAED S3liTH ON THE [Sept. IQI^, 



1 to 2 miles wide. They were thus described by the late Prof. E. S. 

 Tarr (U.S. Geol. Surv. Prof. Paper Xo. 64, 1909, pp. 128 & 129) :— 



' The wave-cut cliff is from 75 to 100 feet in height and nearly 



rerticaL The lower half consists of a riidelj- assorted till-like deposit, including 

 horizontal bands of -well-assorted materials ; the upper half is -well-stratified 

 gravels. . . . Thei'C are layers of sand and gravel, with individual boulders of 

 large size here and there, and with occasional beds of boulders. While most 

 of the layers are gravel, there are also numerous beds of sand and, still more 

 rarely, layers of clay. . . . The pebbles in the gravel layers are well rounded 

 and varied in character, and include a large percentage of foreign fragments. 

 iNo disturbance of the strata such as would have resulted from either ice-thrust 

 or slumping was seen. These gravels attain great thickness, being revealed in 

 some of the stream-cuts to a depth of more than 150 feet.' 



' All evidence that is obtainable points to the conclusion that the gravels of 

 Nunatak Fiord are remnants of marginal accumulations. . . . That they are 

 waterlaid is evident from their stratification ; and that, to some extent, at 

 least, they were deposited in standing water is proved by the large boulders 

 scattered through the gravels, which are too large to have been brought by a 

 glacial torrent, but might have been transported in icebergs. So they were 

 probably accumulated, in part at least, in local marginal lakes. ... It is in- 

 ferred, therefore, that the gravel supply came largely from glacial streams 

 issuing from the main ice -tongue, and that the dip of the layers towards the 

 valley axis is due to the removal of a substratum of ice on which a thick 

 blanket of gravel was deposited. 



The drifts acciimulated at this period would necessarily be of a 

 yaried character : for, on the comparatively flat ground upon which 

 the ice was then resting, any slight disturbances of equilibrium in its 

 mass would be translated into marginal oscillations, which would 

 give rise to varying conditions of deposit of sediment. 



The sands and gravels are not found everywhere : in some cases, 

 no doubt, because the ground was still occupied by ice which after- 

 wards withdrew quickly ; in other cases, perhaps, because they were 

 removed during a re-advance. 



In this connexion it is interesting to note that the largest areas 

 of Lovver Boulder Clay, not covered by sand and gravel, occur near 

 the mouth of Eskdale and along the coast southwards to Annaside, 

 and on the plain south-west of Silecroft and south of Millom. We 

 might conclude, therefore, that the ice-margin rested (at the period 

 which we are considering, after the tongues of land-ice had parted 

 from it) on the Lower Boulder Clay, where the gravels are generally 

 absent, with convex lobes thrust out towards the mouth of Esk- 

 dale, the Whichara Talley, and the Duddon Estuary, and concave 

 embayments, in which sands and gravels were accumulated, swing- 

 ing westwards between these lobes. 



Thus the conclusion, previously expressed (pp. 412 & 420), that 

 the Irish-Sea ice invaded the mouths of the valleys, and in its retreat 

 seemed to withdraw from them reluctantly, is borne out. This 

 wave-like contour of the ice-margin will probably be found to have 

 obtained at other points, both north of Eskdale and south of the 

 Duddon Estuary. 



Accumulations of sand and gravel were formed, not only within 

 embayments in the ice-front, but also in the converse embayments 

 of the land-surface invaded by the lobed ice-margin. 



