CBETACEOUS SERIES IN LINCOLNSHIEE AND YORKSHIEE. 325 



the equivalent of the " Sponge-bed," retains its character as a thin 

 band of compact limestone, differing somewhat in appearance and 

 fracture from the overlying beds, not only through this county but 

 far into Yorkshire. It is generally thicker in Lincolnshire than at 

 Hunstanton, and the line of separation from the underlying bed is 

 not always so well marked as in the Hunstanton cliffs. 



InoceTSimus-beds. — Grey in colour and gritty to the touch, the 

 next 5 or 6 feet of the Chalk are usually compared with the Inocera- 

 mus-heds of Hunstanton. Here the bed appears to me rather more 

 nodular in its character than its Norfolk equivalent, the nodules 

 being of a less gritty material than the surrounding matrix. A 

 marked layer of green-coated nodules occurs about 6 inches above the 

 top of the Sponge-bed in the various pits near Welton. The base 

 of the Chalk appears to retain this gritty character throughout the 

 county. The greater part of the Chalk, for some 30 feet above the 

 basement-bed in this county, may be described as rough and nodular ; 

 this division, however, contains courses of smoother chalk, for ex- 

 ample, the " blue course " (Mem. page 43), near the base, and others 

 near the summit, where the chalk is divided into courses by more or 

 less marked bands of greenish-grey marl. 



The section recorded in the Survey Memoir at Mr. Gutter's pit 

 near Welton (see Section II. p. 366) is that of the face of the quarry 

 which is still worked ; but a little to the north of this, in the older part 

 of the workings further up the slope of the hill, the section can be 

 carried higher. The platy chalk with marked marly bands, the 

 uppermost bed in the section given, can be followed round the 

 pit and seen to continue for about 4 feet more upwards. 



(C.) The Grey Bed. — The equivalent of the Tottenihoe Stone. 



Overlying the Chalk jnst described a bed with strongly marked 

 characters occurs. This is about 3 feet thick, sometimes in more 

 than one course, and of rough rather nodular massively bedded chalk, 

 its darker grey colour showing plainly by contrast with the whiter 

 material above and below. 



Its base, in which there are many pale yellowish green-coated 

 nodules, is here not well defined, the greyer material being let down 

 in pipes and mottlings into the whiter chalk below ; in Central 

 Lincolnshire the lower 6 inches will frequently weather and split into 

 thin flaky pieces, and a band of grey marl forms a line of division 

 from the underlying chalk, which for about a foot down is often hard 

 and " knobbly." It passes up into a course of hard, nodular, and 

 whiter chalk, the top of the bed not being well marked. 



It is very f ossiliferous, and the fauna which I have collected from 

 it is characteristic of the Totternhoe Stone (see page 349), and its 

 structure, when seen in thin sections under the microscope, will 

 compare with that of this stone. 



The " Grey Bed " I believe to be without doubt the contintiation 

 of that which marks the summit of the Chalk Marl at Hunstanton, 

 and therefore it is the representative in Lincolnshire of the Tottern- 



