108 C. E. de Bance — Glaciations of the Lake District. 



Boulder-clays occur both in Lancashire and in North Wales, the one 

 precisely resembling the Upper Clay in composition, colour, and 

 character of included fragments ; the other being a tough, hard, 

 blue or black coloured clay, invariably occurring at levels above 

 300 feet; while the ordinary red Lower Till is hardly ever found 

 above 50. The low-level Clay appears to have been formed under 

 marine conditions, the pebbles and boulders being brought on float- 

 ing ice from the ice-foot surrounding the Lake District, while the 

 high-level Clay is evidently the result of a small ice-sheet of com- 

 paratively local origin, no foreign erratics occurring in it. 



In the railway cutting between Penrith and Keswick two 

 Boulder-clays are seen, the one red, the other blue; the former 

 precisely resembles the Upper Till of Lancashire and Cheshire, 

 while the latter would appear to be the representative of the "land- 

 ice Lower Till " of Lancashire and Carnarvonshire. 



In some places Mr. Mackintosh calls his Clay "2" by the Furness 

 name, "pinel," and to this division he assigns the reddish clay of 

 the Penrith cutting ; and as there can be no doubt that his division 

 " 3 " is the true " Middle Drift " of Prof. Hull, it follows that his 

 divisions " 1 " and " 2 " are the representatives of the two Lower 

 Tills described above. 



In Carnarvonshire the two Lower Tills may be seen, the one 

 resting on the other ; the red lying on an eroded and sea- worn 

 surface of the blue or black clay below, which fact would tend to 

 prove, as I had inferred before visiting North Wales, that the 

 formation of the land-ice Lower Till commenced universally in the 

 north-west of England, before the commencement of the deposition 

 of the Marine Lower Till; at the same time, it is not impossible 

 that, after the subsidence commenced, glaciers reached and even 

 entered the sea, whose moraines were swept off the surface of the 

 ice, and carried by tidal currents southwards, and deposited in the 

 silt there forming, producing the Marine Lower Till: thus simul- 

 taneously land-ice Lower Till might be forming beneath the sub- 

 marine glaciers, and Marine Lower Boulder above it ; and after a 

 time, towards the Middle Drift age, when the climate ameliorated, 

 the ice melted and the Marine Clay sank down in some places 

 quicker than in others, giving rise to those twistings and oblique 

 laminations so often observable in that clay. 



The mounds of drift, associated with roches moutonnees at Grange 

 Bridge, below Derwentwater, appear to have been formed by one 

 of the later glaciers, and once to have extended entirely across the 

 valley below Grange Fells, damming up a lake behind, until the 

 river cut a passage through. The Eev., Mr. Bonney has referred to 

 the fine roche moutonnee on the left bank of the stream at Grange, 

 which has certainly not been touched by the sea, which would be 

 the case if the mounds were formed by it, as suggested by Mr. 

 Mackintosh.' Below Eosthwaite the Derwent receives Stonethwaite 

 Beck, which, a little above that hamlet, is formed by the junction 



1 Geol. Mag., 1866, p. 292. 



