D. Mackintosh — The Drifts of the Lake District. 311 



inferred that land-ice may have planed, smoothed, polished, and 

 striated rock-surfaces, and pushed loose debris forward to the 

 nearest protected situations, but that rounded, smoothed, and polished 

 boulders must have been chiefly shaped by floating-ice and sea- 

 waves,^ — that floating or ground ice glaciated a great part of the Lake- 

 district; that the four drifts were deposited by the sea and floating-ice, 

 though more or less of the clay and loam composing them may have 

 originated as subglacial mud ; that the blue clay was accumulated 



^x \ \ ^, O \ ' MACCLESFIELD 



^rTv.o\ \ \ \ \ \ • ^ 



WREXHAIWO 



■ \ \ \ \ \ \ \ 

 \ \ \ \ \ \ ' 



\ \ \ \ 



\ \ 



O WOLVERHAWIPTOM 



Fig. 9. — Map of the Three Great Granitic Dispersions in South Britain. 

 (Explanation on page 312.) 



under a comparatively shallow sea, and denuded (if not u.pheaved 

 and again depressed), before it was overlaid by the pinel or Lower 

 Brown Boulder-clay ; that the middle sand and gravel were ac- 

 cumulated during the gradual rise, and not during the fall of the 

 land, as Mr. de Kance believes ; that the Upper Boulder-clay of the 



^ According to Forbes no actual glacier is capable of smoothing or polishing 

 boulders, though by means of a gritty base it may smooth and polish rock-surfaces. 



