424 :mE. BEEXARD SMITH ON THE [Sept. I9 12, 



slopes gently westwards from near the 500-foot contour to the 

 300-foot contour, from which it drops abruptly to the 200-foot 

 level. 



During the maximum extension of the ice the surface of this shelf 

 was, like the slopes above it, covered mainly by boulder-clay of a 

 somewhat sandy type (see p. 417). The retreat of the ice seems at 

 first to have been unaccompanied by any great melting, but rather 

 by evaporation, coincident with a falling-ofi* in the amount of 

 precipitation : for no signs of water-action at the margin of the 

 Irish-Sea ice appear in this district above the 500-foot contour, 

 although, apart from the ice itself, the gathering ground was large 

 enough for water to be set in motion, had the snow-line been at a 

 higher level. 



When appreciable melting did take place, moving water began to 

 modify the drift previously deposited upon the shelf or held in the 

 melting ice ; and, since this drift consisted largely of sandy Triassic 

 waste, with granitic and volcanic debris, the resulting products are 

 mainly of a sandy and gravelly nature. 



For example, one of two pits, situated by Whatson Beck, nearly 

 three-quarters of a mile north-north-east of Welcome ^STook, shows 

 6 feet of false-bedded sand with gravelly layers, capped by about 

 3 feet of gravel, some layers of which are disintegrated granite. In 

 the middle of the pit, about 3 feet of red stony clay rests on sand 

 and gravel, and passes laterally into the same. At the top are 

 some large boulders. Sections of a similar nature were seen at 

 several points, as, for example, about a quarter of a mile south-east 

 of Row, near Welcome Nook ; 100 yards east of Park Nook ; near 

 Low Kinmont, and Kinmont Wood. In a pit near the ' Camp,' 

 about 500 yards north-north-west of Corney Church, there was more 

 than 20 feet of coarse roughly-bedded gravel, most of which is 

 bound together by red muddy silt, but there are also beds of cleaner 

 sand and gravel. Some fairly large erratics and pebbles of red 

 sandstone were also noticed here. The gravel extends southwards 

 to and beyond the neighbourhood of Corney Hall, where it forms a 

 distinct feature above the granite, and is exposed a few yards north 

 of the Hall in a pit in which 3 feet of coarse false-bedded granite 

 sand overlies more than 6 feet of gravelly boulder-beds, on a similar 

 deposit at a lower level. In all these cases the well-worn character 

 of the gravel shows that the majority of the pebbles had been 

 carried a long distance by running water before being finally 

 deposited. 



The method of occurrence and nature of the above -described 

 deposits suggest that they were accumulated, as a lateral apron or 

 fan, at the oscillating edge of the ice-sheet, by waters which slowly 

 escaped in a southerly direction through indefinite or now-destroyed 

 channels in the drifts.^ At the same time, the more clearly-stratified 

 portions were doubtless formed in temporary marginal lakes. As 



1 The method of formation of such gravels was discussed by the late 

 Prof. Ealpli S. Tarr in ' Tlie Yakutat Bay Kegion, Alaska ' U.S. Greol. Surv. 

 Professional Paper 64 (1909) chapt. ix. 



