324 ME. W. HILL OK THE LOWEB BEDS OF THE ITPPEJI 



the chalk here extends throughout Lincolnshire and Yorkshire. I 

 propose, in this county, to deal with each separately, and note any 

 important difference which may occur further to the north, or help 

 in the correlation of the Yorkshire series. 



The diagram No. II. is drawn up from sections exposed in the 

 following pits : — that worked by Mr. Eutter | mile S.S. W. of Welton 

 Mill, at the cross roads on the west side of the road to Candlesby (page 

 44 of the Memoir) ; the pit on the opposite side of the road to the 

 Cross Keys Inn, close by the first and forming with it a continuous 

 section ; lastly, a pit | mile west of Welton and 5 mile N.N.E. of 

 the Mill (page 51 of the Memoir). 



(A.) Bed Chalk or Hunstanton Limestone. 



This bed, continuous throughout Lincolnshire, is about 11 feet 

 thick at the southern extremity of the Wolds. It retains this 

 thickness to the north of Louth, but diminishes to 4 feet in the 

 northern part of the county. It is the " amplified counterpart " of 

 the Hunstanton Limestone. Its base seems invariably to partake of 

 the nature of the underlying material, and it is frequently difficult 

 to say exactly where the Eed Chalk begins. It passes up into rough 

 and rather nodular chalk with marly partings, and its summit is 

 frequently, though not always, marked by a thin band of red clay, 

 which separates it from the pinkish or yeUowish-grey chalk, the 

 equivalent of the so-caUed Sponge-bed of Hunstanton, which over- 

 lies it. 



The list of fossils given in the Memoir from this bed is a short 

 one, and I can, with one important exception, add little to it. 

 Belemnites minimus, which occurs commonly in the Gault and 

 Hunstanton Limestone of Norfolk, is also abundant in the Eed Chalk 

 of this county, occurring throughout it, though individuals are more 

 abundant near the base. I am fortunate, however, in being able to 

 add to the list Ammonites interruptus from Withcall, a fact which 

 considerably strengthens our expressed opinion that this bed is the 

 equivalent of the Gault, 



(B.) Lower Chalk. — Chalk Marl. 



The Chalk Marl, as before noted, alters its lithological characters 

 and becomes thinner as it is followed northward. At Hunstanton 

 its base is recognized in the so-called Sponge-bed, which is followed 

 by the grey and gritty Inoceramus-bed, with a layer of green-coated 

 nodules at its base. This, passing up into hard whitish chalk, is 

 finally overlain by a marked course of grey-coloured chalk, also with 

 green-coated nodules at its base. This bed, the representative of 

 the Totternhoe Stone, marks the summit of the Chalk Marl, and the 

 fauna obtained from this division will compare with that from the 

 upper part of it in Cambridgeshire, Hertfordshire, &c. 



" Sponge-bed." — The pinkish or yellowish-white chalk which im- 

 mediately overlies tl e Hunstanton Limestone in Lincolnshire, and is 



