276 LTAS OF ENGLAND AND WALES : 
showed the clays overlaid by Northampton Sands. Here about 
8 feet of blue pyritic clay (with Ammonites Holandrei) was to v 
be seen. 
The clays have also been worked at Thenford Hill quarry, near 
the Camp and Windmill, between Thenford and Thorpe Mande- 
ville. There Mr. Thompson obtained Ammonites Holandrei, 
A. jibulatus, Nucula Hammeri> Leda ovum, &c. ; he regarded the 
clays as belonging to his Lower Leda-ovum beds. Similar beds 
were opened up in a clay-pit near Wappenham. 
Over this area and to the north and north-east, the Upper Lias 
along its main outcrop, is overlaid by straggling outliers of 
Northampton Sands and Great Oolite, and the inclination of the 
ground corresponds generally with the dip of the strata, so that 
the streams draining into the Tove at Towcester flow over the 
dip-slope. This structure indeed prevails over those parts of 
Northamptonshire where the Upper Lias in developed, and 
Mr. Aveline observes that in many places " the brooks have 
merely removed the overlying sands and flow over the top beds 
of the clay, the toughness of which has a tendency to resist any 
further denudation."* 
Outliers of Upper Lias, capped in most cases by Northampton 
Sands, occur to the north-west, at Wardington, Eydon, Arbury 
Hill, Staverton near Daventry, &c. I found evidence in the 
country between Little Preston and Fawsley Park, to show that 
the Basement Beds of the Upper Lias, extend over larger areas 
than are shown on the Geological Survey maps.f 
The clays have been worked in many places for brick-making. The so- 
called " Unfosailiferous beds " having been opened up south-west of Weston, 
near Weedon Lois; between Morton Pinkeney and Sulgrave, between 
Farndon and Chipping Warden, between Everdon and Newnham (where the 
beds are worked beneath the Northampton Sands), at Upper Weedon, on the 
Weedon and Daventry Road near Daventry, in the railway-cuttings between 
Weedon and Daventry, and in a brickyard near Welton, where the clays have 
been preserved through a fault. J 
In the brickyards north of Eydon, the Middle Leda-ovum beds have been 
exposed, yielding Ammonites fibulatus, Leda ovum, &c. Many fossils were 
obtained here by Mr. Beesley, who remarks on their excellent preservation, 
the nacreous layer being present. . 
Other sections have been exposed at Badby, to the E. of Everdon, and 
at Easton Neston near Towcester. 
The main mass of the Upper Lias extends along the valley of 
of the Tove by Towcester to near Castlethorpe. The clay has 
been worked for brick-making south-east of Tiffield, between 
Blisworth and Towcester ; at Kingthorn near Greens Norton, west 
of Towcester (Upper Leda-ovum beds) ; near Silverstone ; Grafton 
Regis, and in other places. 
The evidence obtained in pits near Deanshanger, shows that the 
Great Oolite is separated from the Upper Lias by about 20 feet 
of the Upper Estuarine Series and Northampton Sands. The 
* Geol. part of Northamptonshire, pp. 7, 8 ; and Geol. parts of Northamptonshire 
and "Warwickshire, p. 7. 
f H.B.W., Explanation of Horizontal Section, Sheet 140, p. 7. 
j Thompson, Journ. Northamptonshire Nat. Hist. Soc., vol. iv. p. 16 ; Hep. Brit. 
ABSOC. for 1891, p. 335. 
See also Aveline and Trench, Geol. part of Northamptonshire, p. 8. 
