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On the Chalk and Flint of YorJcshire, as compared with the 

 Chalk and Flint of the Southern Counties of England. By 

 James Mitchell, LL. D. F. G. S. Communicated by the 

 Author.* 



The chalk and flint of Yorkshire, whilst they possess qua- 

 lities sufficient to identify them with the chalk and flint of the 

 southern coimties, have at tjie same time some considerable dif- 

 ferences deserving of attention. 



The district in Yorkshire in which they are found, is exposed 

 to view on the sea-coast, commencing about a mile east of the 

 town of Bridlington, and extending round the bold and lofty 

 promontory of Flamborough Head, and thence onwards to the 

 north, to beyond the heights called Specton. Inwards the chalk 

 district extends through a low range of hills to a point to the 

 east of the town of Mai ton, being about twenty miles from 

 York, and the same distance from Scarborough. 



The Yorkshire chalk is much harder than the chalk in the 

 south. As soft chalk as any in England may be found in the 

 pits on either side of the river Thames, and it is so much so, 

 that the fossils found in it may be cut out or displayed on pe- 

 destals to advantage, with a pen-knife and plate brush. A si- 

 milar chalk is found in Hertfordshire, Buckinghamshire, and 

 Bedfordshire. 



The chalk at Dover, at Norwich, at Lewes, at Brighton, and 

 in the Isle of Wight, is harder; and a still harder chalk is 

 found on Handfast Point and under Ballard Downs, in the Isle 

 of Purbeck ; and the hardest of all which I have examined, is in 

 the quarry at the foot of Corfe Castle, in the same district. But 

 even the chalk of Corfe Castle, superlatively hard as it is, falls 

 short of the stony hardness of the chalk of Flamborough Head, 

 and the district proceeding from it inland. A proof of its hard- 

 ness may be observed in the use made of it in forming the pub- 

 lic roads. There were heaps laid along the road beginning two 

 miles from Malton, and extending onwards six miles towards 

 Scarborough. It was also the material used for several miles on 



• Eead before the Geological Society, London. January 7, 1835. 



