OXFORD CLAY. 325 



The Kellaways Beds may be traced between Bourn and Folking- 

 ham in Lincolnshire, and other divisions of the Oxford Clay have 

 also been noted in that county.^ 



In Yorkshire the Oxford Clay, consisting chiefly of grey shale, 

 attains a thickness of from 120 to 150 feet on the coast, but is 

 much less inland. It occurs at Castle Hill, Scarborough, 

 Gristhorpe Cliffs, Cunstone Nab, etc. (See Fig. 47, p. 309.) 



The Kellaways Rock comprises a variable set of beds of sand- 

 stone, calcareous grit and shale, whose thickness varies from 30 to 

 70 or 80 feet, and even 120 feet. Where seen at the southern 

 extremity of Gristhorpe Bay, the beds are about 30 feet thick, and 

 the fossiliferous band (only 5 inches) occurs at the top, the beds 

 below being destitute of organic remains. In other places the base 

 of the rock is fossiliferous. The rock is exposed at the North 

 Cliff and Castle Hill, Scarborough, Red Cliff in Cayton Bay, 

 Newtondale, Cave, Hackness, etc." It has also been exposed at 

 Drewton on the Hull and Barnsley Railway.^ Mr. Hudleston 

 observes that the Kellaways Rock in Yorkshire is a more compre- 

 hensive formation than in Wiltshire. Taking the whole of the 

 Yorkshire area, the Kellaways Rock, Oxford Clay, and Lower 

 Calcareous Grit, replace one another to a considerable extent, and 

 must be viewed simply as varying parts of one great formation 

 known elsewhere as the Oxford Clay.* The following fossils 

 characterize the divisions of the Clay : — 



Upper Beds. Ammonites peraj-tnatiis (rarely). 



Middle Beds. Small Ammonites, A. crenatiis, etc. 



Lower Beds. Bekiiinites Owciiii, A. Lambcrti, A. athlda, A. crcnatns, etc. 



Varieties of A. cordatus occur throughout the Clay. In the 

 Kellaways Rock the species include A. Jason, A. athleta, A. 

 Goivcrianiis, A. Koeiu'gi, A. macroccphalus, etc. At Coney Birks, in 

 the valley of the Riccal, in Yorkshire, the Kellaways Rock becomes 

 quite a coarse grit, and covers the hill-side with large fallen blocks, 

 one of which measured 27 feet in length by 9 feet in breadth.* 



The Oxford Clay has been reached in the Sub-Wealden boring, 

 near Battle, at a depth of over 950 feet ; and also at Dover. (See 

 Fig. 31, p. 202.) 



Ecofiomic products, etc. 



The Oxford Clay is difficult and expensive to cultivate ; it requires draining, and 

 is mostly under permanent pasture. The ' Dorset-blue ' and the North Wilts 

 cheeses, and that of Stilton, in Huntingdonshire, are among the products of the 

 dairy-farms. (See p. 270.) The old Forest of Braydon (Wilts) was situated on 

 the Oxford Clay. 



^ Jukes-Browne, Geol. South-west Lincolnshire, etc. (Geol. Survey), p. 70. 

 "^ J. Leckenby, Q. J. xv. 4; C. F. Strangways, Explan. Sheets 95 S.W. and 

 S.E. (Geoh Surv.), p. 12 ; 95 N.W. p. 45 ; 96 S.E. p. 9. 

 3 W. Keeping and C. S. Middlemiss, G. Mag. 1883, p. 219. 



* P. Geol. Assoc, iv. 355, 410 ; G. Mag. 1882, p. 147 ; 1884, p. 146. 



* C. F. Strangways, Explan. Sheet 96 S.E. (Geol. Survey), p. 9. 



