310 JURASSIC. 



and the top of the Midford Sands. The term Northampton Sand 

 was proposed in i860 by Messrs. W. T. Aveline and R. Trench.^ 



Traced northwards and eastwards from the Cotteswold area, the Inferior Oolite 

 assumes sandy characters, and it has been shown by the Geological Survey that 

 the lower zone of the Great Oolite (which includes the Stonesfield Slate) inider- 

 goes similar changes. Thus, as Prof. Judd has remarked, the two series of sandy 

 beds are brought together, and as the higher series is almost always unfossiliferous, 

 it was found impracticable, as a rule, in the Oxfordsliire area, to separate the 

 sands of the Great Oolite from those of the Inferior Oolite : hence the term 

 Northampton Sands has unfortunately in that area been applied to the whole mass 

 of variable sandy strata which intervene between the Upper Lias Clay and the 

 upper zone of the Great Oolite.- (See p. 299.) 



In the northern part of Northamptonshire and in Lincolnshire, 

 the Northampton Sands include the Lower Estuarine Series of 

 Prof. Judd, and occur beneath the Collyweston Slates and Lincoln- 

 shire Limestone (Inferior Oolite). Prof. Judd has observed that 

 the Northampton Sands sometimes rest on an eroded surface of the 

 Upper Lias Clay, and in some localities there is no evidence that 

 any part of the INIidford Sands is represented. The thickness of 

 the Northampton Sands and Lower Estuarine Series varies from 

 twenty to eighty feet. The following divisions of the beds have 

 been made in the Northampton district (see Diagram, p. 286) :^ — 



Feet. 

 4. White or grey sand and sandstone, contain- 12 ) ^ rj ■ o • 



mg a plant-bed \ 



3. Thin beds of ferruginous sandstone and 



shelly calcareous beds — very variable, 



being sometimes entirely calcareous, at 



others consisting of white sand and 



sandstone 30 \Fcn-2ioinoiis Beds. 



2b. Coarse oolitic limestone with fossils ) 



2a. Slaty bed ] 4 



I. Ironstone-beds containing Rhynchondla 



variabilis, R. cyjiocephala, etc 35 ) 



Upper Lias Clay. 



Amongst other fossils from the Northampton Sands are Terchra- 

 iula perovalis, Avicula Braamhu^iensis, Gervi/lia acuta, G. Hartmanni, 

 Ltidtia Wrtgh/ii, Pholado7nya fidicida, Grcsslya pe7'egrtna, Isocardia 

 cordata, Hinnites ahjectus, Lima duplica/a, Ostrea gregaria, Pcdcn 

 personatus, P. demissus, Astarte dcgatis, Cardium Buckniani, Cctv- 

 viya Bajodana, CticuUcca cancellata, Trigonia costata, Nerincea 

 dngenda, Nautilus, Bdeinnites giganteus, and Ammonites ISItuxhisona^. 

 The Lower Estuarine Series contains thin scams of lignite and 

 occasionally Cyrena. 



Amongst the localities where the beds may be observed are 

 Kingthorpe, Northampton, Duston (slaty beds), Ellsworth, and 

 Gayton. (See Fig. 46.) At Lincoln the thickness of the sandy 



^ Explanation of Quarter-sheet 53 S.E. (Geol. Survey), p. 8. 

 "^ Geology of Rutland, etc., p. 30. 



2 Sharp, Q. J. xxvi. 358 ; xxix. 285. See also Morris, G. Mag. 1869, p. loi ; and 

 Jukes-Browne, Geol. S. W. Lincolnshire, p. 45. 



