168 
THE CRETACEOUS ROCKS OF BRITAIN. 
which must be some 80 or 90 feet above the base oUthe Chalk. In 
the village of Letcombe Basset a bed of very hard siliceous chalk 
is seen and the same or another bed is exposed in the road-cutting 
on Holborn Hill, west of the village, the beds seen here being as 
follows : — 
ft. 
Hard stony chalk (probably siliceous) ----- 6 
Soft crumbling grey marl ------- 4 
Tough blocky chalk seen for 3 
In the roadway south-east of the church, about 150 feet above 
the base, there is some rather hard and rough greyish chalk re¬ 
sembling Totternhoe Stone, but a sample of this was sliced and 
examined bv Mr. W. Hill, who reports it to be an ordinary hard 
chalk marl, rather full of shell fragments and foraminifera, but not 
comparable with true Totternhoe Stone. 
No good exposures were seen near Wantage, but near Manor 
Farm strong springs issue from blocky chalk at about the usual 
horizon. 
The exposure of the basement beds north of Lockinge has already 
been mentioned (see p. 167). Beds near the base can be seen in 
the main road south of East Hendred and at the Broadway south 
of Harwell, where there are many fragments of Am. [ Schloenb .] 
varians and Am . [Acanth .] Mantelli. Higher beds, which must 
be near the top of the zone, are shown in a small pit south of 
Arfield Farm, consisting of grey chalk weathering into platy pieces, 
and containing Am. varians and Plicatula infiata. 
The middle and upper parts of this zone are well exposed in the 
railway cuttings between Upton and Chilton on the Didcot and 
Newbury line. 
The first cutting near Upton begins at a level of about 60 feet 
above the base of the Chalk Marl. The beds exposed consist of firm 
marly chalk in which Am. [Schloenb.] varians is the most abundant 
fossil. Microscopic examination of this chalk showed it to have 
the ordinary characters of Chalk Marl, except that the remains of 
siliceous sponges, both mesh and spicules,* were present in some 
abundance. 
In the next cutting the lowest beds are rather hard, and contain 
many fossils, including sponge remains; these beds pass up into 
marly and blocky chalk, of which there is from 16 to 20 feet, and 
the highest beds contain two courses of hard grey chalk. These 
courses are probably the lowest of those which are seen at the 
entrance of the next cutting east of Chilton, where the following 
succession can be measured : — 
# 
See Quart. Journ. Geol. Soc., Vol. xlv. p. 408. 
