LINCOLNSHIRE LIMESTONE. 313 



Lincolnshire Limestone. 



This formation comprises beds of compact cream-coloured and 

 marly limestone and shelly oolitic ragstone, and was named 

 by Prof. Judd, from its development in Lincolnshire.^ The 

 beds rest on the Collyweston Slate near Stamford, and on the 

 Northampton Sands in other localities. Some of the beds are 

 largely made up of Corals, which usually have been converted into 

 masses of finely crystallized carbonate of lime. Among the genera 

 noticed are Thamnastrcca, ClaJophyllia, IsastrcBa, Thccos?tiilia, etc. 



Among other fossils are the Mollusca Ammonites Miirchisona:, 

 A. suhradiatus, Natica ciiicta, Tancrcdia axiniformis, Pieropcrna, 

 JVerincEa cingenda, Cerojnya Bajociana, Pholadomya fidiada, Pinna 

 cuneata, Modiola Sowcrbyana, Astarte elc^ans, Pecten pumiliis ; the 

 Brachiopoda, Terebratula submaxillafa, T. perovalis, etc. ; also the 

 Plants Pecopteris, Ptcrophylliim, and Palccozamia. 



The Lincolnshire Limestone and the Collyweston Slate are 

 placed on the horizon of the Inferior Oolite, a position for the 

 limestone which was first suggested by the Rev. P. B. Brodie and 

 Dr. Lycett. Prof. Judd groups the Limestone as the zone of 

 Ammonites Soiverbyi. 



In Lincolnshire the oolitic limestones which constitute the 

 formation attain a thickness of about 200 feet, forming the "Cliff" 

 escarpment : they thin out near Kettering, being only eight feet at 

 Raven Wood near Glendon, two miles from that town. At Stamford 

 the thickness is about eighty feet. Prof. Morris has remarked that 

 in some quarries, as near Ketton, a line of separation is marked in 

 the Oolitic rocks by borings of Lithodomi, which lived in the 

 partly consolidated rocks previous to the deposition of the Upper 

 Estuarine Series. 



At Oundle and Higham Ferrers the Northampton Sand is 

 directly overlaid by the Upper Estuarine Scries (base of Great 

 Oolite). IMr. Sharp thus grouped the beds:- — 



Stamford. Oiindle. 



i Lincolnshire Limestone \ ty ^\ 



with Collyweston Slate, i*- ^^^°^^''' 

 Northampton | Lower Estuarine Series. Lower Estuarine Series. 

 Sand. ( Ironstone Rock. Ironstone Rock. 



Prof. Judd considers that the Lincolnshire Limestone was de- 

 posited under moderately deep-sea water conditions, but there are 

 evidences in its lower portion of littoral accumulations. 



North of Lincoln about eighteen feet of limestone is exposed, 

 the upper part flaggy, and containing a shelly limestone with many 

 small Gasteropods ; below are compact creamy and blue-hearted 



^ Geology of Rutland, etc., pp. 33, 139. See also J. Morris, Q. J. ix. 317, G. 

 Mag. 1869, p. 102 ; S. Sharp, Q. J. xxix. 225 ; P. B. Brodie, Proc. Cottesw. 

 Club, i. 52, ii. 132 ; Ann. Nat. Hist. 1S57 (2), xix. 56 ; G. Mag. 1S69, p. 236 ; 

 and Jukes-Browne, Geol. S.W. Lincolnshire, p. 52. 



" Q- J- xxix. 2S3. 



