212 ME. G. W. LAMPLTJGH ON THE SPEETON SEEIES [May 1 896, 



applied to the Lincolnshire Carstone. But HHoplites Deshayesii be 

 in place in Lincolnshire as in Norfolk, it would appear that where 

 the Carstone is fully developed its lower portion must lie within 

 the ' Zone of Belemnites brunsvicensis,' in which event the interval 

 between it and the Tealby Limestone cannot be great. 



Indeed under any circumstances, if I am right in thinking that 

 no break exists at Speeton between the ' Passage-marls ' and the 

 clays containing B. brunsvicensis, Hoplites Deshayesii, and Amaltheus 

 bicurvatus, any unconformability which may exist at the base of 

 the Carstone, as supposed by Mr. Strahan, must possess a relatively 

 small time-value where that deposit overlies the Tealby Limestone 

 Series, since on comparison of this part of the Lincolnshire sequence 

 with that of Speeton there is seen to be little or nothing lacking. 



At the upper boundary of the deposit it is very probable that 

 there may be in some degree a lateral as well as a vertical passage 

 into the Red Chalk. That the accumulation of sand in the shal- 

 lower or more exposed areas probably continued for some little time 

 after the deposition of the chalky sediment had commenced in 

 adjacent regions is, I think, directly suggested by the evidence 

 made known to us by Mr. "W. Hill in his careful study of the lower 

 beds of the Upper Cretaceous rocks. 1 With the Red Chalk com- 

 menced that period of slow depression, which in its later stages 

 brought back once more an uniformity of conditions over the 

 eastern part of England which had not existed since Kimeridgian 

 times. This depression swept away the more local influences which 

 had hitherto prevailed in South Yorkshire and North Lincolnshire, 

 where a belt of country had been slowly brought up within reach 

 of the denuding agencies and gradually planed down. South and 

 east of the elevated area, even where the marine conditions were 

 continuous, the proximity of land and the gradual change in its 

 outline affected from time to time the factors which govern the 

 accumulation of sediments, so that in Mid-Lincolnshire the 

 deposits of this period are marked by their local and changeful 

 characters. 



V. Statement of the Coeeelation. 



The result of this investigation is to show that in Lincolnshire, 

 as in Yorkshire, the various species of belemnites present in the 

 rocks afford the most natural and convenient means for classifying 

 the strata ; but that the well-defined zones which they form do not 

 always coincide with the lithological divisions. 



Of these zones, that of Belemnites lateralis appears to be quite as 

 fully represented in Lincolnshire as at Speeton. The 'Zone of 

 Belemnites jaculumf which occupies so large a proportion of the 

 Speeton Clay, is in most of the Lincolnshire sections condensed into 

 narrow limits, and may be in part unrepresented. 



The ' Zone of Belemnites brunsvicensis ' is well exhibited, but from 

 the unfossiliferous character of some of the sediments and the lack of 



1 Quart. Journ. Geol. Soc. vol. xliv. (1888) p. 320. 



