CRETACEOUS SEBIES IN LINCOLNSHIRE AND YORKSHIRE. 



331 



General Succession of the Lower Beds of the Upper Cretaceoiis series 

 in Lincolnshire, 



ft. 



(Hard, creamy, yellow chalk without flints, con- 

 taining a marked layer of whitish chalk — the 

 columnar bed about 15 



f „ p 7? 7 f -^"^ ^^ dark grey shaly marl, sometimes stained 



" /?w- I j,g^(jjg}j (jY purple ; in some localities including 



[ a layer of harder whitish chalk 2 



^Bedded whitish chalk in courses, sometimes sepa- 

 rated by thin marly bands 21 



The upper part of this division is coloured pink 

 . in central Lincolnshire. 



"• Indefinitely bedded and rather marly chalk, with 



marked marl bands 16 



This bed is also partly coloured pink in central 

 Lincolnshire. 



Zone of Belem- 

 nitella plena. 



Grey Chalk. 



Grey Bed.' 

 f 



Chalk 

 Mai-1. 



< 



j A marked course of grey-coloured chalk, with 



1 green-coated nodules at its base 2 to 4 



Rough chalk, with marked marl bands, smoother 



courses at intervals, base grey and gritty 30 



f Hard compact bed of chalk, sometimes stained 

 yellowish red, the colour graduating into the 

 bed below 2 



c tJ J 



r ATTT T -f "^^^ Chalk or Hunstanton Limestone 



* \ Thins in the northern part of the county to 4 ft, 



§ II. Yorkshire. 



The evidence concerning the sequence of the Lower Beds of the 

 Upper Cretaceous series in Yorkshire is of the scantiest, and far 

 different from that of Lincolnshire, where quarries are of frequent 

 occurrence at all horizons. There are, in fact, so far as I know, 

 only three exposures along the whole escarpment of the Wolds 

 where a reliable section of the sequence can be obtained. Small pits 

 or patches of bare chalk afford just sufficient evidence of the con- 

 tinuation of beds of marked lithological characters, but, as will be 

 explained, little reliance can be placed on their relations to beds 

 above or below. 



There is a gradual rise in the base of the Chalk in Yorkshire as 

 we proceed to the N.W. along its outcrop, from 150 feet at Welton, 

 near the Humber, to about 600 feet between Leavening and Acklam. 

 It will be seen in the sequel that this point nearly coincides with 

 that at which the Eed Chalk is thinnest and the overlying beds 

 show a slight attenuation. 



With the gradual change in the direction of its outcrop from 

 N.W. to E.N".E. the base begins to descend, and it ultimately nearly 

 approaches sea-level at Speeton. But in neither case does its line 

 of outcrop coincide with the true strike of the beds, which must be 

 taken along a line joining the points where its outcrop is intersected 

 by the plane of the sea, i. e. N.jST.E. from North Ferriby to Speeton 

 Cliff. The centre of the Yorkshire basin therefore is somewhere to 

 the east of Driffield. The northern escarpment of the Yorkshire 



