154 Saunders — Geology of South Bedfordshire. 



pieces, or plates, are not differentiated — the shield in both is of a 

 single piece ; but it is obvious that in Cephalaspis the rostral, orbital, 

 and comual element predominate, whilst in ScapJiaspis the discal 

 region chiefly is represented. 



EXPLANATION OF FIGURES. 



Fig. 4. Eelievo ) of Bidymaspis Grindrodi, sp., noT., from the Lower Old Eed, 



5. Intaglio j Ledbury. 



6. Outline of the shield of Didymaspis. 



7. Bone-lacunse from the posterior portion of the shield of the same. 



8. Outline of Auchenaspis, 



T 



V. — Notes ok the Geology of South Bedfordshike. 

 By J. Saunders, Esq. 

 HE Geology of South Bedfordshire is now being exhibited 

 X more fully than hitherto, as the extension of the Midland 

 Eailway from Bedford to London is opening up a series of sections 

 in the newer Secondary rocks which characterise this part of 

 the county. The following notes were chiefly taken during a walk 

 made last summer along the line, between the towns of Bedford 

 and St. Alban's (Herts). For the first few miles the excavations are 

 slight, and exhibit only the Drift sands and gravels of the rich 

 valley of the Ouse, though these are well worthy of careful examina- 

 tion for flint implements and mammalian remains, which have been 

 discovered on the north side of the river, at Biddenham, by J. Wyatt, 

 Esq. About three miles from Bedford is an excavation in the Oxford 

 clay ; the upper portion is dark brown merging into dark blue 

 beneath, and it aboimds in fossil wood in various stages of carboniza- 

 tion, the colour of which ranges from brown to jet black ; it is so abun- 



.■a 



•?, 



fo 



g 

 1 



1 



.s 



< 



(M 



ES 



a b c d e f g 



Diagram to Illustrate the Geology of South Bedfordshire. 

 a. Oxford clay. 6. Greensand. c. Gault. d. Tottemhoe stone, c. Supposed bed of clay 

 under the Lower Chalk. /. Lower Chalk, g. Chalk with flints. The dip of the strata 

 is a little greater than that of the surface of the country. 



dant in places that some of the excavators fancied they were coming 

 upon a coal-mine. Eunning through the mass of clay is a profuse 

 abundance of roots and fibres in inextricable confusion. Belemnites 

 are common in this bed, as is also Ammonites Calloviensis in the 

 clearages, but the fossils are so hopelessly compressed and fragile as to 

 defy all attempts at extrication, save in the smallest specimens. This 

 formation extends to Ampthill, where it is more largely developed, 

 and where a tunnel is carried through it immediately beneath the Park. 

 The approaches to the tunnel exhibit a series of beds of clay, brown 

 at top and merging into dark blue below, with intermediate bands of 



