INTRODUCTION. 23 
the North Sea with the exception of a short break in Yorkshire. But about half- 
way between these two points, in the very centre of England, the deposits of this 
age are very meagre, and yield scarcely any Gasteropoda, indeed but few fossils of 
any sort. That portion of the outcrop which lies between Banbury and a little east of 
Blisworth represents this series in its most degraded condition, and at the point 
where the new railway to Northampton diverges from the old line (north of Roade 
station) a few feet of unfossiliferous sand is all that intervenes between Bathonian 
beds and the blue shales of the Upper Lias. I have very little doubt that if we 
could follow the beds for a short distance on the dip (i.e. to the south-south- 
east) it would be found that the Inferior Oolite had disappeared entirely. We are 
therefore prepared for the entire absence of the Inferior Oolite throughout the 
south-east of England, as proved by numerous borings, and we perceive that this 
south-easterly attenuation, which has been noted at several points in the midland 
and west midland districts, is but the prelude to entire extinction. 
But to return to the outcrop, this extreme thinning and change of beds in the 
centre of England is no doubt due to the configuration of the old land surface at 
the time of the deposition of the Inferior Oolite. Into these physical details there 
is no need for us to enter on the present occasion ; it is enough for our purpose that a 
markedly new phase of the Inferior Oolite is gradually attained in the country 
which lies to the east of the main line of the London and North-Western Railway. 
The line as thus indicated may be said roughly to divide the two great regions of 
the Inferior Oolite from each other, that on the north-east being on the whole of a 
less marine character than the more typical and better known region to the south- 
west. But, just as the Cotteswold type differs from that of Dorsetshire, so in the 
great north-eastern division does the Northampton-Lincoln type differ from that 
of Yorkshire. 
Hence we may divide the Inferior Oolite of England geographically into four 
principal districts as follows : 
No. 1. The Dorset District, including part of Somerset in the direction of the 
Mendips. 
No. 2. The Cotteswold District, extending from the neighbourhood of the Men- 
dips to a line across the centre of England approximately indicated by the London 
and North-Western Railway. 
No. 3. The East Midland District representing the outcrop of beds of Inferior 
Oolite age in Northants (east of the above line), Rutland, Lincoln, and perhaps 
south-east Yorkshire as far as the Pocklington axis. 
No. 4. The Yorkshire Basin constituting an isolated area and presenting many 
peculiar features. 
Of course there may be some room for difference of opinion as to the boundaries 
of these four areas or districts, but generally speaking each of them is characterised 
