314 JURASSIC. 



limestones, shelly in places. In the north-western part of Lincoln- 

 shire the Rev. J. E. Cross divides the beds as follows : — 



Lincolnshire Limestone, 36 feet. 



San ton Oolites, containing Hi unites ahjedus, Gcrvillia acuta, etc., with soft 

 ferruginou^s bed at base (Dogger).^ 



Mr. W. A. E. Ussher has locally divided the beds as follows : — 



Ponton Beds. White and cream-coloured oolite. 20 to 30 feet. 



Kirton Beds. Bluish-grey limestone, oolitic in places. 30 to 40 feet. 



Basement Beds, consisting of band of hydraulic limestone, and shale (Lower 

 Estuarine Series of Yorkshire) ; these beds would be about 15 to 20 

 feet thick, including ferruginous beds of the Dogger Series or 

 Northampton Sand. 



Economic products, etc. 



The Barnack Rag, a light brown shelly oolite, is said to have been quarried by 

 the Romans, and the quarries exhausted four hundred years ago, although a great 

 deal of stone has in recent years been sold as Barnack Rag.^ Peterborough 

 Cathedral and Crowland Abbey were in part constructed of this stone. The 

 Ketton Stone, a cream-coloured oolite, about eleven feet thick, was used in the 

 construction of modern works in Peterborough and Ely Cathedrals, and in many 

 buildings in Cambridge, for St. Dunstan's Church in Fleet Street, London, etc. 

 The beds yield valuable building-stone also at Casterton, Geeston, Collyvveston, 

 Morcot, Denton, Corby, Weldon (twenty-five feet of stone), Geddington, Pipwell 

 Abbey, etc. 



The " silver bed " of Ponton was used in the construction of Lincoln Cathedral ; 

 the "roe-stone" bed is also employed for building. The beds are worked at 

 Haydor, near Grantham, and in the railway-cutting at Ancaster. 



The Stamford Marble, as seen in Tinkler's quarry, Stamford, is described by 

 Prof. Judd as a hard blue-hearted limestone, one foot to eighteen inches in 

 thickness, containing Corals, also Ncrimva cingetida, N. triplicata, and other shells, 

 teeth and palates of Pycnodiis and Strophodtis. When polished, it is a favourite 

 material for chimney-pieces.^ 



North of Lincoln the stone is worked at the Dean and Chapter pit, and other 

 places; here the lowest and best bed is called the "silver bed." At Maidwell, 

 north of Northampton, the stone (Maidwell Limestone) has been worked. The 

 beds, besides being largely used for building-purposes, are used for road-metal and 

 burnt for lime. The term Northamptonshire Lime was applied to the beds 

 in 17S8 by the Rev. John Michell. 



The soil on the Lincolnshire limestone is light and not very productive ; but 

 good barley is grown in some places. 



1 Q. J. xxxi. 121. 



^ Porter, Geol. of Peterborough, p. 114. 



2 Geol. Rutland, etc., p. 160. 



