GEOLOGY 



Norton, and according to Mr. Beesley the Marlstone was 1 1 feet thick, 

 while the underlying shaly and sandy beds were 16 feet in thickness. 1 

 The lower beds yielded numerous fossils including fine specimens of 

 Cypricardia. 



North-west of Banbury the Marlstone rock bed is very well de- 

 veloped and forms a plateau which rises gradually from an altitude of 

 500 feet at that town to the famous escarpment of Edge Hill, 710 feet 

 above sea-level. The rock forms a rich brown arable soil specially 

 suitable for wheat growing. At Edge Hill the stone is a tough earthy 

 limestone of brown and greenish hues, used for building, paving and 

 road stone, and it has a thickness of 25 feet. There are large quarries 

 on Burton Dassett Hill, a few miles to the north-east, while outliers of 

 the beds occur at Bodington, Napton, and Upper Shuckburgh. 



The Liassic sea now became deeper again, and we have the clayey 

 series of the Upper Lias thrown down in the quiet waters. These beds 

 consist chiefly of bluish-grey clay and shale with nodules of clayey lime- 

 stone. The basement beds are pale earthy limestones, frequently nodular, 

 and their junction with the Middle Lias is generally well marked. The 

 organic remains include various fishes, and the ammonites A, annulatus, 

 A. fibulatus, A. serpentinus and A. communis ; belemnites occur, together 

 with numerous bivalve shells, and several insects, notably some allied 

 to the dragonflies. 



Near Ilmington the thickness of the Upper Lias has been estimated 

 by Mr. S. G. Hamilton at 1 20 feet ; at the tunnel north of Chipping 

 Norton, according to Mr. Beesley, it is about 36 feet, while near Ban- 

 bury it increases to about 60 feet. It occurs in the form of numerous 

 outliers and in valley bottoms northwards of Chipping Norton towards 

 Tysoe, and Upper Lias fossils have been found by Mr. Brodie in crevices 

 of the Marlstone rock bed on Edge Hill, 2 while still farther north there 

 is an outlier of Upper Lias, capped by Northampton Sands, on the hills 

 near Burton Dassett. 



At the close of the Liassic period a shallowing of the sea appears 

 to have set in, caused presumably by movements of uplift ; the climate 

 was warm and the waters of the sea were favourable to the existence of 

 vast numbers of aquatic animals whose remains make up a large part of 

 the succeeding Oolitic rocks. 



The Inferior Oolite Series is found in outlying patches near Ilming- 

 ton and also in the south of the county along the eastern side of the 

 Vale of Moreton. The series consists of two sub-divisions, the Midford 

 Sands below and the Inferior Oolite above. 



The Midford or Cotteswold Sands form a passage bed between the 

 Lias and the Oolites ; the materials of which they are made up and the 

 fossils found in them exhibit a gradual change from the conditions which 

 prevailed during the formation of the Upper Lias to those under which 

 the Oolites were deposited. The beds, 30 to 1 50 feet thick, consist of 



1 Woodward, op. cit. pp. 221, 222. * Woodward, op. cit. p. 270. 



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