178 D. MACKINTOSH ON THE DEIFT-DEPOSITS 



13. On the CoEEELATioN of the Drift-deposits of the Worth- west 

 of England with those of the Midland and Eastern Counties. 

 By D. Mackintosh, Esq., E.G.S. (Read January 7, 1880.) 



Contents. 

 Introductory Eemarks. 

 Southerly Extension of the Upper Boulder-clay of Cheshire &c. into South 



Shropshire. 

 Probable Extension of the Upper Boulder-clay along the lower course of the 



Severn valley. 

 Dispersion of angular debris from the Malvern Hills. 

 Low-level drifts south of Worcester. 

 Redistribution of Triassic Pebbles. 

 Drift- deposits of the East-Midland counties, around Nuneaton, Coventry, 



Kenilworth, and Leamington, and in Leicestershire, Rutlandshire, &c. 

 Drift-deposits around Gainsborough. 

 Correlation of the Drift-deposits of West Yorkshire with those of Lancashire 



and Cheshire. 

 Concluding Remarks and Suggestions. 



Introductory JRemarhs. 



Mr paper on boulders*, in the Quart. Journ. GeoL Soc. for August 

 1879, terminated abruptly, owing to my having been advised to 

 postpone the concluding part, on the Correlation of the Drift- 

 deposits, which will form the main subject of this paper. But 

 before dismissing the special subject of boulders, I would refer to 

 a letter received from Mr. Charles Darwin, E.R.S. &c. (who was the 

 first to elucidate the boulder-transporting agency of floating ice), con- 

 taining an account of the great Ashley-Keath boulder (see p. 442 

 of paper), which he was the first to discover and to expose, by exca- 

 vating on one side and beneath it, so as to find that the block rested 

 on fragments of ISTew Eed Sandstone, one of which was split into 

 two and deeply scored. I have little doubt that this boulder went 

 south from some of the mountains around Ennerdale, as I have seen 

 boulders resembling it on Dent Hill, near Cleator. The facts men- 

 tioned in the letter from Mr. Darwin would seem to show that the 

 boulder must have fallen through water from floating ice with 

 a force sufficient to split the underlying lump of sandstone, but not 

 sufficient to crush it. 



Southerly Extension of the Upper Boulder-clay of Cheshire Sfc. 

 into South Shropshire. 



In the western part of the plain of East Denbighshire and Shrop- 

 shire the Dpper Boulder-clay degenerates into a loamy gravel, which 



* At p. 450, line 20 from the top, for " Criffel granites " read "varieties of 

 Criffel granite ;" and at line 24 from the top of the same page, for " Boulder- 

 clay," read "Lower Boulder-clay." At p. 453, line 2 from bottom of table, for 

 " mass," read " lower part." At p. 448 I ought to have mentioned that the 

 distinguished local authority on the striated rock-surfaces around Liverpool, Mr. 

 Morton, F.G-.S., had recently been led to doubt some of his former opinions 

 concerning their origin, and to favour the theory of floating ice (see Proe. 

 Liverpool Geol. Soc. ibr 1876-77, pp. 294, 295). 



