1 9 2 Northamptonshire and L incolnshire. 



Oxfordshire, these beds get still more sandy, the lime- 

 stone of the Inferior Oolite disappears by degrees, sandy 

 beds replace them, which are overlaid directly by the 

 sands of the Great Oolite, the two forming together 

 what are generally known as the Northampton Sands. 

 By-and-by, in the district of Rockingham near Ged- 

 dington, the Inferior Oolite Limestone begins to re- 

 appear, overlying the lower part of the Northampton 

 Sands, and lying flat, and thickening by degrees, it 

 forms the surface of a great tract of country towards 

 Stamford and Thistleton, in Northamptonshire and Rut- 

 landshire, also towards Grantham, and in Lincolnshire, 

 being always underlaid by the Northamptonshire Sand. 

 The Inferior Oolite of this district is well known as the 

 Lincolnshire Oolite Limestone. The sands beneath it 

 have been largely worked in Northamptonshire for 

 ironstone, and their upper part is occasionally white, 

 ' with remains of plants, sometimes vertical, also thin 

 seams of lignite, and miniature underdaysj while 

 6 thin seams containing Cyrena (a fresh-water bivalve 

 shell) occur in this part of the series. These beds have 

 been distinguished by Mr. Judd as the Lower Estuarine 

 Series.* 



Above the Lincolnshire Oolite Limestone there lie 

 certain strata, named by Mr. Judd the Upper Estu- 

 arine Series., forming, in his opinion, the lowest part 

 of the Great Oolite of this area. They are well seen in 

 some of the cuttings of the Great Northern Railway, 

 and on the top of the Inferior Oolite Limestone quarries 

 at Ketton, Clipsham, and Casterton. As described by 

 Mr. Judd, there are in these strata 'bands of sandy 

 stone with vertical plant markings and layers of shells, 



1 'Geology of Rutland,' &c. J. W. Judd, p. 92, 'Memoirs of the 

 Geological Survey.' 



