Vol. 52.] IN YORKSHIRE AND LINCOLNSHIRE. 211 



h. The Carstone. 



The lithological characters and stratigraphical relations of the 

 pebbly ferruginous sand which in Lincolnshire overlies the deposits 

 above described, and extends upward to the Red Chalk, have been 

 carefully set forth in the Survey Memoirs l and in Mr. A. Strahan's 

 excellent paper on the subject in this Journal. 2 Except in the layer 

 immediately below the Red Chalk, where Belemnites minimus and 

 Terebratula biplicata are found, fossils are of very rare occurrence 

 in it. Such as have been discovered are contained in eroded 

 phosphatic nodules, and are supposed to have been derived from 

 lower strata which have been destroyed. 



The species recorded 3 are : Ammonites speetonensis ? ; A. plicom- 

 phalus ? and Lucina ? from a nodule-bed at its base near Otby ; and 

 A. Deshayesii, A. triplex, Requienia?, Astarte, Corbula, Modiola, 

 Myacites, Pholadomya, Cyprina, and Teredo, from Claxby. 



.Not having myself succeeded in finding any of these fossils in the 

 deposit, I have been unable to investigate their mode of occurrence 

 and the character of the supposed ' pebbles ' with which they are 

 associated, and therefore am not in a position to discuss their 

 origin. But from the nature of the list and the general features of 

 the nodules in the stratum, I am inclined to consider their derivative 

 nature not proven. At any rate, Ammonites Deshayesii is not far 

 from its proper horizon, and, as already stated (p. 198), I am satisfied 

 that where this species occurs in the Carstone at Hunstanton it is 

 not derivative, but in place. The other ammonites mentioned, being 

 all uncertain species, are of slight account in the discussion, while 

 the remaining determinations of the list are too incomplete to afford 

 any information. 



As regards the stratigraphical relations of the deposit, I can cor- 

 roborate Mr. Strahan's account of its upward passage into the Red 

 Chalk, and the presence of Belemnites minimus in it just below the 

 junction. In the southern part of its outcrop the Carstone has a 

 thickness of about 40 feet, but northward it thins away, until in the 

 last sections seen before reaching the Humber it remains only as a 

 pebbly base to the Red Chalk. Both phenomena are exactly repro- 

 duced, as shown in an earlier part of this paper, by the ferruginous 

 sands exposed in a few places along the western edge of the Yorkshire 

 Wolds, which are no doubt the northern equivalents of the Carstone. 

 And as it has been also shown that these Yorkshire sands can be 

 correlated with much probability with the ' Passage-marls with 

 Belemnites minimus ' (A) of Speeton and Knapton (which, it may 

 be noted, contain at the first-mentioned place ' lydites ' and other 

 small gritty particles), it follows that the same correlation must be 



1 ' Country around Lincoln,' pp. 105 et bcqq. ; ' East Lincolnshire,' pp. 23 

 et seqq. 



2 ' On the Lincolnshire Carstone,' Quart. Journ. Geol. Soc. vol. xlii. (1886) 

 p. 486. 



3 Ibid. p. 488 ; the Claxby list was supplied to Mr. Strahan by Mr. H. 



Q.J.G.S. No. 206. 



