412 ME. BEEXAED SMITH ON THE [Sept. I912, 



(2) The Ieish-Sea Ice. 



In the ueighbourhood of Eootle the Ennerdale ice had become 

 to all intents a part of the Irish-Sea ice, while the Eskdale ice 

 still maintained its identity in some degree, yet by the time 

 Whitbeck was reached it, in turn, was almost inseparable from 

 the Irish-Sea ice. After passing Whitbeck the edge of the ice was 

 forced first into the mouth of the Whicham Valley near Silecroft, 

 diverting the flow of the ice down that vaUey, as above explained 

 (p. 410), and then some distance up the broad estuary of the 

 Duddon, where it also affected the flow of the local ice. Having 

 incorporated the Whicham- Valley and Duddon ice it passed across 

 parts of Purness and Morecambe Bay, and impinged upon the 

 Fleetwood and Blackpool coastline. 



The evidence for these movements will be found below in the 

 description of the drifts left by the Irish-Sea ice, which it is now 

 proposed to set forth in some detail, and at the risk of subsequent 

 repetition. 



VI. The Deift-Deposits of thr Plaix axd the Adjacent 

 Hill-Slopes. 



In describing the drifts of the plain ^ between St. Bees and 

 the Duddon, Mackintosh recognized three divisions in upward 

 succession : — 



(a) A Lower reddish, yellowish, or yellowish-brown Boulder Clay 

 or ' pinel,' ofteu varied by a light bluish or greenish tint, and 

 containing the greatest number of large boulders. This, he 

 considers, was mainly derived from the waste of the volcanic rocks 

 and Coal-Measure shales of Cumberland. 



{b) The sand and gravel formation of the plain, containing pebbles and 

 a few boulders of most of the rocks found in the clay above and 

 below it. 



(c) An Upper red loamy clay (pai-tly derived from the waste of 

 Permian [Triassic] strata), containing few boulders. 



In his discussion of the general results of his studies- — embodied 

 in eight papers — he considers that the rounded, smoothed, and 

 polished boulders must have been chiefly shaped by floating ice 

 and sea-waves. He infers that floating or ground-ice glaciated a 

 great part of the Lake District ; that the drifts were deposited by 

 the sea and floating ice ; that more or less of the clay and loam 

 comprising them may have originated as subglacial mud ; that the 

 Middle Sand and Gravel were accumulated during the gradual rise, 

 and not during the fall of the land, as C. E. De Bance believed ; and 

 that the Upper Boulder Clay of the plains was deposited during a 

 succeeding submergence, the vertical extent of which was at the 

 very least 1300 feet. 



^ ' On the Dispersion of CriflFell Granite & Caldbeck Porpliyry over the Plain 

 of Cumberland' Geol. Mag. vol. vii (1870) pp. 567-68. 



^ ' On the Drifts of the West & South Borders of the Lake District, & on 

 the Three Great Granitic Dispersions ' Geol. Mag. vol. viii (1871) pp. 310-12. 



