18 James Croll — Transport of Wastdale Crag Blocks. 



part of the country had been derived from the debris of the rocks of the 

 Midland Counties." ^ He came also to the conclusion that the slate 

 fragments may have been derived from Charnwood Forest. In the 

 Vale of More ton he found erratic boulders from two feet to three feet 

 in diameter. The same northern character of the drift of this 

 district is remarked by Professor Eamsay and Mr. Aveline, in their 

 Memoir of the Geology of parts of Gloucestershire. In Leicester- 

 shire and Northamptonshire the officers of the Geological Survey 

 found in abundance drift which must have come from Lincolnshire 

 and Yorkshire to the north-east. 



Mr. Lucy, who has also lately directed attention to the fact that 

 the Cotteswold Hills are scattered over with boulders from Charn- 

 wood Forest, states also that, on visiting the latter place, he found 

 that many of the stones contained in it had come from Yorkshire 

 still further to the north-east.^ 



Mr. Searles Wood, jun., in his interesting paper on the Boulder- 

 clay of the North of England,^ states that enormous quantities of the 

 chalk debris from the Yorkshire Wold are found in Leicester, Eut- 

 land, Warwick, Northampton, and other places to the south and 

 south-west. Mr. Wood justly concludes that this chalk debris could 

 not have been transported by water. '* If we consider," he says, 

 " the soluble nature of chalk, it must be evident that none of this 

 debris can have been detached from the parent mass, either by water 

 action, or by any other atmospheric agency than moving ice. The 

 action of the sea, of rivers, or of the atmosphere, upon chalk, would 

 take the form of dissolution, the degraded chalk being taken up in 

 minute quantities by the water, and held in suspension by it, and in 

 that form carried away ; so that it seems obvious that this great 

 volume of rolled chalk can have been produced in no other way than 

 by the agency of moving ice ; and for that agency to have operated 

 to an extent adequate to produce (a quantity that I estimate as 

 exceeding a layer 200 feet thick over the entire Wold), nothing 

 less than the complete envelopment of a large part of the Wold by 

 ice for a long period would suffice." 



T have already, on a former occasion, assigned my reasons for 

 disbelieving in the opinion that such masses of drift could have been 

 transported by floating ice.* But if we refer it to land-ice, it is 

 obvious that the ice could not have been in the form of local 

 glaciers, but must have existed as a sheet moving in a south and 

 south-west direction, from Yorkshire, across the central part of 

 England. But how is this to harmonize with the theory of glacia- 

 tion, which is advanced to explain the transport of the Shap 

 boulders ? 



The explanation has, I think, been pointed out by a writer in the 

 " Glasgow Herald," of the 26th November last, in a review of Mr. 

 Lucy's paper. 



^ Quart. Journ. Geol. Soc, vol. xi., p. 492. Memoir of the Country around 

 Cheltenham. 18o7. Geology of the Country around "Woodstock, 1859. 



2 Geol. Mag., Vol. VII. p. 497. ' Quart. Journ. Geol. Soc, vol. xxvi. p. 90. 



* Philosophical Magazine for November, 1868. 



