182 
LOWER OOLITIC ROOKS OF ENGLAND : 
Northampton Beds' 
Fissile and somewhat oolitic 
slaty beds (White Pendle or 
Duston " Slate ") with Be- 
lemnites [Lima, Hinnites 
abjectus'] : more or less cur- 
rent-bedded ... 
Even layers of brown cal- 
careous sandy rock (Yellow 
and Best Brown Hard 
building- stone). Cardium 
cognatum 
Blue-hearted calcareous sand- 
stone (Rough Eag and Hard 
Blue Eag), the blue portion 
more distinctly oolitic than 
the outer brown portions ; 
Astarte elegans (with shell 
preserved), Lima, lignite, 
Trigonia, [Ceromya bajo- 
ciana, Gervillia, Pholadomya 
fidicula, Cardium cognatum}, 
Ammonites opalinus, Nautilus 
[Ironstone] 
FT. IN. FT. IN. 
4 to 6 
about 12 
6 to 
- about 
All the beds are more or less calcareous and sandy, with fer- 
ruginous veins. Where protected the top-beds are massive. Occa- 
sionally broken-beds may be observed, and they appear to be due 
to the dissolution and removal of calcareous matter. Sharp has 
given a detailed account of this section, and the local names and 
other remarks in square brackets, as well as eome of the thick- 
nesses, are given on his authority. 
He mentions that at the et Old Slate-quarry Close," a stone- 
pit was opened some years ago, ancf there were then exposed 
several of the old workings that had been carried on, at some 
unknown and distant time, for the obtaining of slate 'alone. The 
old process was that called " foxing," still sometimes adopted at 
Colly weston; shafts were sunk, and the "slate" was extracted 
from beneath the overlying beds by means of adits.* 
At Harleston there is a quarry showing the stone-beds, which 
are worked to a limited extent and are rather more sandy than at 
Duston. The upper strata present a broken appearance in a sort 
of " Gully," features evidently produced by dissolution of the car- 
bonate of lime.f Beneath come " slaty " beds of sandy rock, locally 
termed the " White bed/' Below come the main stone-beds 
(Harleston Stone), which are used for building-purposes. Astarte 
elegans and other fossils are to be found. 
West of Duston and near Harpole, white sands are met with, 
attaining a thickness of 30 feet ;J and these beds with the fer- 
ruginous rock and building-stone of Duston, may be compared 
with those seen at Newbottle Spinney (see p. 176). 
* Quart. Journ. Geol. Soc., vol. xxvi. p. 370. 
f Similar features have been noticed by Sharp, Quart. Journ. Geol. Soc., vol. xxyi. 
p. 363. 
t Aveline, Gaol, part of Northamptonshire, p. 11. 
