MIDDLE CHALK—BEDFORDSHIRE AND HERTFORDSHIRE. 465 
Part of this zone is exposed in the quarries at Coldharbour, near 
Dunstable. The upper level of the chief quarry shows about 
30 feet of massive white chalk with a layer of buff-coloured shaly 
marl. The apparent bedding is really curvilinear jointing, for the 
planes curve and run into one another. There are no flints, and 
the chalk is used in the manufacture of whiting. Fossils are rare. 
Another good section occurs at the Lime and Whiting Works, 
half-a-mile north-east of Luton Station. There are three levels to 
the quarry and they give a combined section through about 60 feet 
of chalk, the whole being rather soft homogeneous white chalk 
with a few scattered flints and two layers of grey marl in the central 
part. G-alerites subrotundus is common; Inoceramus Guvieri, 
Spondylus spinosus, and Terebratula semiglobosa also occur. 
The chalk of this zone occupies a large area near Hitchin, and a 
good section of its lower beds are exposed in Mr. Bansome’s quarry 
near the railway station, which is a continuation of the section 
given on p. 464 ; above the beds there noted there is about 70 feet 
of soft white chalk with a few scattered flints, but no regular layer 
of flints, except that near the top of the underlying zone. Galer- 
ites sulyrotundus and large Terebratula semiglobosa are common, 
with Terebratulina gracilis var. lata, Ptychodus decurrens and 
other fossils. Another pit in the fields further south shows 
rather higher beds of soft chalk containing Spondylus spinosus, 
which does not seem to occur in Mr. Bansome’s quarry. 
A quarry a quarter of a mile south of Little Wymondley shows 
15 feet of soft white chalk, with a band of grey marl and a layer 
of flints above it; Spondylus spinosus , Inoceramus Cuvieri ? and 
Terebratula semiglobosa occur here. 
The lower beds of this zone are to be seen in a quarry about a 
mile W.S.W. of Baldock, which shows soft white chalk without 
flints, but including a band of nodular chalk with yellow stains ; 
the soft chalk contains Terebratulina gracilis var. lata, Ter. 
striata, small Rhynchonella Guvieri, and other fossils. 
Higher beds with a few flints and Inoceramus Cuvieri are seen in a 
pit south-east of Baldock. 
There are two quarries in this zone near Boyston, one east and one 
south-west of the town. That to the eastward is the deepest, and the 
beds shown are : — 
feet. 
Thin-bedded chalk with scattered root-like and elongate flints 12 
Layer of grey shaly marl. 
Massive thick-bedded chalk, with a line of scattered flints at 
the top - 
Layer of irregular knobby flints. 
Thick-bedded white chalk S 
Spondylus spinosus and Discoidea Dixoni were obtained here. 
The other quarry is not more than 25 feet deep ; it shows similar 
white chalk, with some flints and a thin layer of grey marl. Spondy¬ 
lus spinosus occurs here also with Inoceramus Cuvieri and Tere¬ 
bratula semiglobosa. 
