INTRODUCTION 



13 



a. Gritty limestone, 6 ins. 



b. Laminated sands and clays, 1 ft. 

 r. Oolitic limestone, 3 ft. 



Forest Marble. 



In this section the basal beds of Shipton-on-Cherwell are seen, but the under- 

 lying Forest Marble lias changed, in 2400 yards, from clay to fossiliforous lime- 

 stone, and the greatest care is therefore necessary in examining the matrix of the 

 recorded fossils. 



At Kirklington there is a very large quarry in the Bathonian limestone, with 

 only a capping of not very fossiliforous Cornbrash, the records of which can only 

 be received with caution. 



At Tslip likewise the fossils were obtained from a band of Cornbrash capping 

 about five feet of Forest Marble Clay, underlain by Bathonian Oolite, but at the 

 date when the fossils were collected by Mr. J. F. Whiteaves a wider meaning was 

 given to the name of Cornbrash than is adopted here or generally received. 

 Mr. Whiteaves, however, has kindly informed me which specimens he remembers 

 to have been obtained from the lower strata, then associated with the Cornbrash, 

 so that any source of error may be eliminated. 



Fia. 1. — Unconformity near 



if the 



18. Bicester to Bedford. — Two quarries are situated near Bicester Workhouse 

 showing rubbly Cornbrash overlying more massive building stone. The farther 

 one shows two sections along the sides of a re-entering angle, in which the lower 

 beds change, while the upper, with Avlcula ecldnata, remain constant (text-fig. 1) ; 

 thus the Cornbrash rides over a false-bedded section unconformably. 



At Blackthorn the rubbly Cornbrash is very distinct from the well-bedded 

 Forest Marble strata, and yields many of the characteristic fossils. On the road 

 to Buckingham only shallow openings are shown, and at Fringford it is only 

 reached at the base of an Oxford Clay brickyard. At Akely brickyard there is 

 now a very curious section, greatly affected by faults, the effects of which arc 1 hard 

 to realise; but the Cornbrash itself seems to be represented by a limestone 

 irregularly packed with fossils faulted between infra-Callovian clay and Great 

 Oolite Clay. At Bedford the Cornbrash is only exposed by cutting beneath the 

 Oxford ('lay. Such was the case in an excavation made for the Midland Railway 

 on the south side of the main line. Many fine fossils were thence obtained, and 

 some of the stone is now placed in the wall adjoining the entrance 1 to the 

 A nipt li ill tunnel. 



