INFERIOR OOLITE : TOWCESTER. 179 
By the wood, to the north of the brickyard, a sand-pit has 
been opened to obtain material for moulding bricks. This pit 
exposed 10 feet of white, grey, and brown, carbonaceous and 
ferruginous sand, with loamy and clayey beds here and there ; and 
towards the top ochreous veins, while the beds are tinged purple 
in places. 
Mr. R. Trench observed that in the railway-cutting south-east 
of Blisworth, the Northampton Sand is exceedingly tain, so that 
eastward, but a single layer of stone represents the rock. 
At the south end of Blisworth Canal Tunnel the sand is only 
5 feet thick, resting on Upper Lias Clay, and overlaid by blue 
clay of the Great Oolite ( = Upper Estuarine). This was also 
the case at Gullet Coppice brick-kiln, south-east of Towcester. 
Underlying the Great Oolite at Deanshanger, west of Stony 
Stratford, there is a stiff bluish-black and greenish-coloured clay 
with lignite and (according to the workmen) also bones. This 
division belongs to the Upper Estuarine Series ; it was exposed 
to a depth of 3 ft. 6 ins. at the brickyard at Deanshanger, and was 
said to have been proved in an adjoining well to a depth of 18 feet. 
White Sand (Lower Estuarine Series), yielding water, was met 
with below ; but the overlying clay was said to get white and 
sandy towards the base, so that the Upper Estuarine division was 
probably rather less than 18 feet in thickness.* 
These attenuated representatives of the Northampton Beds do 
not appear to be fossiliferous, and they suggest that the formation 
does not extend much farther to the south-east. As remarked by 
Prof. Judd, , " It is probable that at some points the extremely 
variable beds, constituting the Northampton Sand, thin out alto- 
gether, and that the higher beds of the Great Oolite series lie 
directly upon the Lias."f This is the case probably at Olney, 
where the Upper Estuarine clays may rest directly on Upper Lias 
Clay. 
Dnston and Northampton to Maidtvell. 
Iron-ore is largely worked in the Northampton Sand of 
Northamptonshire, pits being opened to a depth of 1 or 20 feet, 
or even more, at Gayton and Blisworth, Hunsbury Hill, Duston, 
Spratton and Brixworth, Wellingborough, Finedon, Kettering, 
between Burton Latimer and the Cranfords, Twywell, Slipton, 
Gretton, and Easton near Stamford. 
The frequent changes undergone by the Northampton Sand 
render the actual extent of the profitable ironstone in each locality 
a matter of considerable uncertainty, and one that needs to be 
proved by trial-holes. Throughout the whole of the district from 
* H. B. W., Explanatioa of Horizontal Section, sheet 140, p. 5. 
f Geol. Kutland, p. 31. 
M 2 
