Thus there are four several areas within a comparatively small space (Fig. 1) in which the whole series of beds occurring in each, from the Great Oolite (including the same) down to the Upper Lias, are accessible ; and these severally I propose to describe.
They are situated at or about : — 1. Kingsthorpe ; 2. Northampton ; 3. Duston ; 4. Blisworth. The individual beds of these several localities vary considerably ; but collectively they may be said to present the following General Section, in which I have given maximum thicknesses in feet, and which, indeed, may be accepted as the typical section of a large portion of the county of Northampton : —
General Section of Oolitic Beds in the Northampton District.
feet.
X Stratified and variegated Clay at Blisworth, containing abundant Ostrea subrugulosa 2
A White Limestone, disposed in beds of from a few inches to about three feet in thickness, much fissured, varying in character, and containing characteristic Great-Oolite fossils 25
B Blue and Grey Clay, dug for brick-making, with ferruginous band at base, and Great-Oolite fossils 15
XX [Line of unconformity]
C White or Grey Sand, more or less coherent, and with occasional ferruginous stains — sometimes quarried for building stone. A plant-bed is usually found in this sand 12
D A series of very variable beds, composed sometimes of ferruginous sandstone in thin layers, which overlie calcareous beds containing shelly zones, false bedding being frequent : sometimes the whole section consists of calcareous rock with false bedding ; sometimes it presents a series of beds of compact ferruginous sandstone, with no fossils. In one instance, the entire section consists of white sand and sandstone, with no fossils 30
Coarse Oolitic or subcrystalline Limestone, with fossils, overlying a calcareo-arenaceous slate, like Collyweston slate 4
E Beds, chiefly consisting of Ironstone, containing Rhynchonella variabilis, and R. cynocephala, and Ammonites bifrons at the base 35 Upper Lias Clay.
I have provisionally distinguished the beds of D and E in this section, because I think I have evidence in the Northampton and Duston areas and elsewhere to justify me in so doing ; the particulars of this I will give in my description of the beds of those areas. I admit, however, that the beds of E may be simply the lowest beds of D under another and local phase of conditions ; but in this case a considerable addition must be made to the thickness of D.
Lists of Fossils from the several localities are given in Tables at the end of the Memoir.
