242 PE0CEEDING8 OF THE GEOLOGICAL SOCIETY. [Apr. 3, 



The same pink bed is seen in several other chalk-pits in the neigh- 

 bourhood, e. g. one near Ruckland, and two others on the main road 

 known as the High-street, between Tetford Hill and South Ormsby. 



Since my observations were made in Lincolnshire, I find that the 

 Eev. Mr. Wiltshire has published* a very clear and detailed account 

 of the magnificent section at Speeton ; this section I have placed for 

 comparison alongside of that from Louth. In both cases I regard 

 the lowest only of the red beds as the Hunstanton hmestone, and 

 the others to be more or less local red beds intercalated in the 

 lowest portion of the chalk. The remarkable agreement, however, 

 in thickness, lithology, and fossils, of the uppermost of these beds in 

 each series suggests (in spite of the distance of the sections) the 

 possibility of their being parts of one widely spread stratum (see 

 fig. 3). 



lY. The Beds below the Hujststanton Limestone. 



a. Unconformity at the base of the Hunstanton Limestone. — The 

 great physical break in the succession of strata, which has been so 

 well described by Prof. Phillips as occurring between the Chalk and 

 Speeton Clay of Yorkshire, is quite as strongly marked in Lincoln- 

 shire. This want of conformity of the Hunstanton Limestone with 

 the beds below is manifested in several ways. 



1. The strike of the Upper Cretaceous beds is not parallel with 

 that of the Neocomian and Jurassic beds, the result of which is that 

 in going northwards we find the latter overlapped and covered up 

 by the former. Thus the sands which form the upper member of the 

 Neocomian series, and which are probably 70 to 80 feet thick at their 

 most southern exposures in this county, appear to thin out gradu- 

 ally northwards, and finally disappear altogether near Caistor. The 

 limestones and clays, which form the second member of the series, 

 are in their turn similarly overlapped, no trace of them being seen 

 north of Clixby, while the sands and sandstones forming the third 

 member disappear in like manner near Elsham: North of this place 

 the Hunstanton limestone is found lying successively on the difierent 

 zones of the Kimmeridge Clay. On crossing the Humber, it is well 

 known that the " Red Chalk" is found lying in succession on each 

 of the members of the Jurassic formation, but that near Grimstone, 

 its strike becoming greatly altered, and running nearly at right 

 angles to its former course, the various Oohtes and Speeton beds re- 

 appear from underneath it in reverse order. 



2. The thickness of the upper member of the Neocomian series 

 increases in going eastwards as well as southwards. This I am 

 enabled to prove by means of the curious inliers which have been 

 already described as occurring in the midst of the Chalk Wolds. Thus 

 in the valley of Thoresway the upper sands are more than 12 feet 

 thick, while at the main line of outcrop in Nettleton Yalley, a mile 

 to the west, they have almost entirely disappeared f. Similarly, 



* See Wright's Mon. Brit. Cret. Echin. p. 8, Mon. Pal. Soc. vol. xv. 

 t I find that this fact was noticed, but without any explanation of it being 

 given, by Mr. Lee in 1837. 



