136 LIAS OF ENGLAND AND WALES: 
The boring extended to a depth of 68 feet beneath this. The 
grouping of the divisions of the Lias is given with considerable 
hesitation ; it is doubtful if Upper Lias be present. 
We have, however, evidence to show that the thickness of the 
Blue Lias limestones, which in this neighbourhood include the 
zones of Ammonites planorbis, A. angulatus, and A. Bucklandi, 
attain a thickness of 76 feet. This thickness becomes reduced at 
Twerton to 66 feet,* as proved in a boring at the coal-pit ; and it 
is much about the same thickness at Bath.f 
Of the clayey beds of the Lower Lias, near Bath, we have few 
sections and but little palaeontological information. A brickyard 
south of the Great Western Railway and east of Twerton station, 
showed about 15 feet of brown and blue mottled marly clay with 
ochreous nodules, and bands of fissile sandy and calcareous stone ; 
and these beds overlie stiff blue clay with Belenmites. 
At the Bath waterworks, situated in the valley east of Swains- 
wick, Moore obtained Hippopodium ponderosum, a fossil exceed- 
ingly rare in the district to the south, but abundant at certain 
horizons near Cheltenham, and further north. 
Lonsdale estimated the total thickness of the Blue clay and 
marl (above the Blue Lias limestones) at Bath at 200 feet ;J and 
this argillaceous series includes the beds up to the Midford Sands 
at the base of the Inferior Oolite. 
Chew Magna and Bristol to Purton Passage. 
The Lower Lias forms a broad platform north of Chew Magna 
on which lies the Inferior Oolite of Dundry. The higher beds of 
the Lias in this area are so rarely exposed that but little is known 
about them. The Lower Lias may be about 350 feet thick 
Ammonites Turneri has been obtained from the Lower Lias at 
the Reservoir at Barrow Gurney. Northwards at Castle Farm, 
on the Bedminster Road, the limestones have been quarried in 
places. We find brown clays and limestones, resting on dark 
blue clays, with bands of yellow (iron-stained) limestone, near 
the top of which Mr. E. Wilson has obtained some Gasteropoda. 
The fossils include Ammonites angulatus, Nautilus, Pleurotomaria, 
Lima gigantea, L. Hermanni, &c. showing that here the zone of 
A. angulatus is represented. 
Bristow noted a quarry west of the high road at Upper 
Knowle, south-east of Bristol, where the lower beds with Lima 
gigantea, and Ostrea liassica, were shown || ; and Moore recorded 
* De Kance, Rep. Brit. Assoc. for 1875, p. 132. 
f See section by Moore, at Kingsmead Street, Bath. In the account given, too 
great a thickness is assigned to the White Lias. Quart. Journ. Geol. Soc., vol. xxiii. 
p. 4'.)6. 
J Trans. Geol. Soc., sir. -2, vol. iii. p. 243. 
See section hy W. W. Stoddart, Wright, Lias Ammonites (Palseont. Soc.), p. 143. 
j| Vertical Sections (Geol. Survey), Sheet 40, N.o. 4. 
