OF THE UPPEE CRETACEOUS EN" WEST SUEEOLK AXD XOEEOLK. 563 



band of nodules beneath the Totternhoe Stone, but he failed to 

 recognize the true horizon of the latter, correlating that stone and 

 the overlying beds with his zone of Belemnites felenus. The list of 

 fossils which he gives as obtained from these beds shows an assem- 

 blage which might have been obtained from the Totternhoe Stone of 

 Eur well or Cherry Hinton. 



In 1880 one of us suggested that the Inoceramus-he&s might be 

 the representative of the Totternhoe Stone, thinking that the whole 

 of the Chalk-marl must have thinned out between Cambridge and 

 Hunstanton, and not imagining that it could have passed into such 

 hard chalk as that which forms the lower part of the Hunstanton 

 section. The recognition of the Totternhoe Stone above the hard 

 Chalk-marl of Stoke Ferry and the discovery of similar stone in a 

 similar position at many intervening localities have, however, con- 

 vinced us that the Inoceramiis-be&s lie below the real representative 

 >of the Totternhoe Stone. 



The white nodular limestone (so-called Sponge-bed) which directly 

 overlies the Red Chalk is about a foot and a half thick, and sepa- 

 rates readily from the beds above and below ; the inequalities 

 between its under surface and the Bed Hock are rilled with a deep- 

 red, nodular, ferruginous material, which Dr. Johnstone informs us 

 consists largely of peroxide of iron. We think there can be little 

 doubt that this white limestone is the same bed as that overlying 

 the marly Upper Gault at Grimston, Boydon, and Dersingham, 

 its character and thickness at the last-mentioned locality being just 

 the same as at Hunstanton. The great importance of this identi- 

 fication has alreadj 7 been indicated (p. 552), and will be more fully 

 discussed in the sequel. 



The Eed Eock below is certainly divisible into two portions or 

 layers, if not into three, as under : — 



3. Hard lumpy reddish chalk, or mottled red and white. 



2. Eough, nodular, red limestone passing down into 



1. Deep red gritty rock, softer at the base. 

 The commonest fossils in 1 and 2 are Belemnites minimus and 

 Terebratida biplicata, in 3 Exogyra Rauliniana and broken shells of 

 Jnocerami. Por further details respecting this well-known rock we 

 may refer our readers to Mr. Wiltshire's paper (Quart. Journ. Geol. 

 Soc. vol. xxv. p. 185). 



C. Zones of Holaster subglobosus, Belemnitella plena, 

 and Ehynchonella Cuvieri. 



In Cambridgeshire the chalk which overlies the Totternhoe Stone 

 presents the following succession in descending order : — 



feet. 



Base of - f Bough, nodular, shelly chalk 40 



Middle < Sandy, yellowish, nodular rock in thick beds (Mel- 

 Chalk. [ bourn Rock) about 3 



fSkaly marls enclosing band of bard white nhalk 



j | (zone of Bel. plena) -A 



fvTxk ^ Firm white chalk passing down into whitish chalk, 



| which changes rapidly into next 50 



^Grey chalk, blocky and fine-grained 30 



