362 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 9,
observable on the roadside at d, whence a spring flows, except
during drought : springs occur at other points of the same junction ;
and a stream dividing Kingsthorpe and Northampton takes its rise
from the same.
I have not obtained fossils from this Clay at Kingsthorpe, except at the point of junction, although frequently in other localities Ostrea Sowerbyi and some other Great Oolite fossils abound in it. Until recently, it was worked for brick-making at e, near Buttock's Booth.
Its base is marked by a ferruginous band of from a few inches to a foot in thickness, observable at its junction with the underlying sand at a pit immediately north of Kingsthorpe, on the Brixworth road, marked f, and at other places.
The pit last mentioned (f) is at the base of the hill between Kingsthorpe and the limestone quarries, and exposes a section of about 12 feet of a white or grey sand, C, the Upper Division of the Northampton Sand*. The line of junction with the clay above is irregular, affording evidence of an eroded surface, and marking an unconformable division between the Great and the Inferior Oolite — a division observable over a considerable area, and in perfect accordance with a certain important fact, to which I shall hereafter allude.
This Sand is stratified, exhibits in places ferruginous stains, and is occasionally varied by the occurrence of argillaceous bands and patches. It is more or less coherent, and sometimes so indurated as to make a very durable building-stone, formerly much quarried, many public and other buildings in Northampton having been constructed of it during the last century.
It yields no fossils ; but near its base is a plant-bed : a band, from 6 inches to a foot in thickness, made up of thin horizontal layers of sand separated by dark laminae (which, when first split, present a surface indented apparently with leaf- and stalk-markings, filled with vegetable matter), overlies a bed in which are what appear to be numerous vertical root-perforations, penetrating to a depth of from one foot to two feet.
Beneath the plant-bed is a somewhat ferruginous bed of dark brown sandstone, apparently unfossiliferous. This is the upper bed of the very variable series which I have grouped under D, as the Middle Division of the Northampton Sand.
A characteristic section of this series of beds may be seen in the Nursery or "Shittlewell" pit (g), a few hundred yards south of Kingsthorpe.
Section of the Nursery or Shittlewell Pit.
ft. in.
1. Very ferruginous Sandstone, in thin layers, sometimes shivered 3 ft. to 4 0
2. Ferruginous Sand, sometimes indurated into stone 2 6
- For the division of the Northampton Sand into Upper, Middle, and Lower,
see Diagram of General Section (p. 380).
