NOTICE OF CUTTINGS IN A DISTRICT OF THE LONDON AND 

 BIRMINGHAM RAILWAY, 



BETWEEN 



Castle-Thorp, Northamptonshire, and Bletchley, Buckinghamshire. 

 By the Rev. Josiah Bull, Jun., F.G.S. 



During frequent visits to a portion of the London and Birmingham Rail- 

 way, some facts have fallen under my observation which have induced me to draw 

 up the following notice, although my acquaintance with geology is limited, and I 

 have little opportunity of acquiring a practical knowledge of subjects connected 

 with it. The opinions I entertain may, consequently, be incorrect, but facts can- 

 not be useless, and I therefore willingly make a statement of them. 



The line of railway between Bletchley and Castle-Thorp nearly traverses the 

 breadth of the Oxford clay, or rather a stratum of clay, which has been regarded 

 as constituting the widest part of that formation south of Huntingdon. There is 

 certainly an uniformity in the character of this deposit, throughout its whole 

 extent ; but it by no means agrees with the ordinary features of the Oxford clay, 

 nor even with that formation in its immediate neighbourhood. Its fossils are dif- 

 ferent, and many of them evidently extraneous. It presents, also, other appear- 

 ances which shew that this deposit must have originated under circumstances of a 

 totally different nature to those which were present during the deposition of that 

 formation. 



The first point at which my observations have commenced is Castle-Thorp, 

 on the borders of Northamptonshire. At the time I visited this spot, there was 

 a cutting of about eighteen feet in depth through the deposit to which I have 

 alluded, and the nature of which I shall presently describe. There was also a 

 section, of a similar character, about half a mile from this, upon the south side of 

 the hill. The line immediately proceeds across the valley of the Ouse, where a 

 large viaduct is erecting. Beyond this point, at the north side of the valley, is 

 a cutting of considerable depth, through horizontal strata of gravelly sand and 

 clay, and boulders of limestone. Here also occur, in a horizontal position, large, 

 fiat, tabular masses of limestone, having a yellowish brown exterior, and being 

 blue within. A little farther on, the same limestone occurs in a large mass, 

 forming a stratum, which dips at a small angle towards the north. This lime- 

 -stone is covered by a clay similar to that at Thorp. Beyond this hill is the valley 

 of Bradwell Abbey, and the ground rises again towards the village of Loughton. 

 Here is a very fine section opposite the church at Loughton, the depth of which 

 will not be less than forty feet, when the summit of the hill is reached. The 

 depth, at present, is about twenty-eight feet through the same bed of clay ; and I 



VOL. I. K 



