1867.] JUDD — LINCOLNSHIRE WOLDS, 229 



wMch special attention will be directed in the present communica- 

 tion), namely, that there are several beds of red chalk in this county, 

 in some localities of very similar lithological character, and only 

 distinguishable by a careful examination of their fossil contents. 

 Still further confusion has arisen, in other instances, from mistaking 

 a series of limestones, ironstones, and clays which present in places a 

 very marked oolitic structure, but which are of undoubted Neoco- 

 mian age, for part of the Jurassic formation. 



In the attempt to unravel the somewhat comphcated geology of 

 this district, the best clue is afforded by the remarkable beds for 

 which Mr. Seeley has proposed the name of the " Hunstanton Lime- 

 stone"*; and my first systematic efforts were directed to a careful 

 mapping of the outcrop of this stratum across the county. Through- 

 out the district now under consideration it serves as an excellent 

 datum line, the relations of the other beds to which can usually be 

 determined. Owing also to a combination of very pronounced litho- 

 logical characters with a most distinct and characteristic assem- 

 blage of fossils, it can be traced with comparative ease wherever 

 the country is not too thickly covered with drift ; and although it is 

 of no great thickness, its position between the Chalk and the Neoco- 

 mian formations invests it with much interest. The following 

 pages will be devoted to a description of the Hunstanton series as 

 developed in Lincolnshire, with a more general account of the strata 

 which he respectively above and below that series. 



II. The Hunstanton Limestone. 



a. Outcrop of the series in Lincolnshire. — The only localities of 

 these beds in this county, hitherto recorded, are South Ferribyf, 

 LouthJ, and Brinkhill§. It will be seen in the sequel that the red 

 beds at the second of these places do not belong to the Hunstanton 

 series, no outcrop of which occurs within five miles of that town. 



The section at Hunstanton is so well known, and has been so 

 frequently described, that it will not be necessary for my present 

 purpose to do more than call attention to one or two facts concern- 

 ing it. The bed of red limestone is at this place 4 feet in thickness, 

 and is divided by very distinct planes of stratification into three 

 nearly equal courses. The lowest of these courses graduates into 

 the " Carstone " beneath, while the upper one is separated by a 

 variable seam of red clay from the '' Sponge-bed," a layer of hard 

 white chalk, 15 to 18 inches thick, and full of the so-caUed " Spongia 

 paradoxica;^' there is never any appearance of gradation in colour 

 between the red and the white beds. 



The most south-easterly point in Lincolnshire at which I have 

 succeeded in detecting this series of beds, is a pit in a field on 

 the right-hand side of the road leading from Gunby to Welton- 



* Ann. & Mag. Nat. Hist. 3rd ser. vol. vii. p. 233. 

 t Wiltshire, " On the Eed Chalk of England," Geologist, 1859, p. 267- 

 X Ibid. p. 268. Seeley, " On the Eed Limestone of Hunstanton," Ann. & Mag. 

 Nat. Hist. April 1861. 



§ Wiltshire, "On the Ked Chalk," where the name is misprinted "Brickhill.'* 



