406 CRETACEOUS. 



but has an undulating boundary, cutting across the beds obliquely.* 

 Red bands occur again in the hard chalk of Speeton (zone of 

 Holaster suhglohosus). The lowest bed of Red Chalk is the equiva- 

 lent of the Hunstanton Limestone (see sequel), and it has been 

 traced from Speeton along the western margin of the Yorkshire 

 Wolds, by Market Weighton, west of Hull, and southwards on the 

 western border of the Lincolnshire Wolds to Hunstanton. 



The zone of Belemnitella plena has not been recognized ; while that of Belem- 

 nitella vmcro7iata is wanting, although this species and B. quadrata have been 

 recorded from the highest beds at Bridlington. These beds are rich in Sponges. 

 Large columns of flints like Paramoudras have been noticed at Flamborough.'' 

 The flints as a rule are greyish or white, and splintery. Much of the Chalk is 

 excessively hard.^ Layers of brown carbonaceous clays, one or two feet thick, 

 have been noticed in the Chalk near Londesborough. 



LINCOLNSHIRE. 



The Wolds of Lincolnshire, which are formed of the Chalk, 

 are, as Prof. Judd has pointed out, much covered with superficial 

 deposits ; hence the district does not present that uniformly bare 

 and arid appearance so characteristic of the Chalk ; in fact, nearly 

 the whole of it has now been brought under the plough, and with 

 the most satisfactory results. 



The Chalk of this area is divided as follows : * — 



]\Tiddlo Chilk ^ Chalk with flints and Lioceramus Bronsniarti. 



Hard rocky Chalk. 



T^ ^^ r^u^ii i Chalk. Zowe o{ Holaster subs^Iobosiis. 

 Lower Chalk. } ^^^ ^^^^^^ 



No fossils indicating Upper Chalk have been determined, but possibly these 

 beds are concealed beneath the Drift. The highest beds comprise Chalk with 

 nodules and large tabular masses of flint, and sometimes Paramoudras ; beneath 

 comes a great thickness of hard chalk without flints, characterized here and there 

 by bands of pink and red chalk, one well-marked bed at Louth being about six 

 feet in thickness. The Louth red chalk can be traced over a considerable area : 

 it contains Holaster siibglobosus, Discoidea cylmdrka, Tercbratida biplicata, T. obesa, 

 etc., species which occur also in the lowest bed of White Chalk. This is under- 

 laid by the Red Chalk proper (Hunstanton Limestone), twelve feet in thickness, 

 the upper part of which (called the ' Sponge-bed ') contains the curious markings 

 termed Spottgia paradoxica (see p. 408), that also occur higher up in the White 

 Chalk without flints. Bclc7>inites tiihiii/tus and other fossils occur in this Red 

 Chalk.* (See p. 407.) The western entrance of Withcall Tunnel, east of Donning- 

 ton, shows Lower Chalk resting on Red Chalk.'' 



^ J. F. Blake, G. Mag. 1874, p. 364 ; P. Geol. Assoc, v. 240, 251, vi. 170 ; 

 C. Barrois, Ibid. vi. 166 ; C. F. Strangways, Explan. Sheets 93 N.E., 95 S.W. 

 and S.E. (Geol. Survey) ; Phillips, Geol. Yorkshire, Part L edit. 3, pp. 54, 95 ; 

 Rev. T. Wiltshire in Wright's Monog. Brit. Cretaceous Echinoderms (Palseontogr. 

 Soc), p. 8 ; Geologist, ii. 262. 



- R. Mortimer, P. Geol. Assoc, v. 347. 



3 Dr. J. Mitchell, Proc. G. S. ii. 113. 



* Jukes-Browne, Geol. E. Lincolnshire (Geol. Surv.), 1886. 



* Judd, Q. J. xxiii. 235, xxiv. 223. 



^ A. Strahan, P. Geol. Assoc, viii. 386. 



