140 LIAS OF ENGLAND AND WALES: 
the foreshore, and protruding some way in places beneath the 
Alluvial mud of the Severn. It was observed by George 
Cumberland in 1822, that " We can walk at low-water on the blue 
lias of Fretherne, to the extent of half a mile, as on an extensive 
level floor, and there see enormous ammonites under our feet, 
some exceeding four feet in diameter."* The beds are no longer 
exposed to this extent, but, as at Llantwit in Glamorganshire, 
we can observe the clusters of fossils here and there on the 
Liassic pavements : Pecten textorius, Avicula cygnipes, Lima 
gigaittea, and Pentacrinus occurring abundantly in portions of the 
rock, which elsewhere appear unfossiliferous. 
The most noteworthy fossils of Fretherne are the Gryphaas 
(G. arcuata). They occur in profusion here and there in the 
shales and limestones, and I have nowhere seen finer examples. 
They may be found at all horizons in the cliff-section, but are 
most abundant in the lower beds, and especially in a band of 
shale, above which I obtained a small example of Ammonites 
angulatus. The beds belong to the zones of A. angulatus and A. 
Bucklandi, and perhaps include higher stages, for Mr. Lucy 
reqords A. semicostatus, and I obtained a specimen of A. obtusus. 
Judging by these fossils the thickness of the zone of A. Bucklandi 
is not above 20 feet. It is noteworthy, however, that A. Bucklandi 
and A. semicostatus occur together about mid-way up in the beds 
exposed; and Mr. Lucy notes A. Conybearci together with A. 
Johnstoni, Avicula cygnipes, etc., in a band near the base of the 
cliffs. Many other fossils have been recorded by Messrs. Brodie 
and Lacy, including the Involutina, also Discina babeana (Orbicula 
Townshendi), spines of Cidaris, vertebrae of Ichthyosaurus, &c.t 
In an account of the Geology of Awre, published in 1 830, the 
Rev. C. P. Wilton,| at that time curate of the parish, records 
many fossils from the Blue Lias. These include Ammonites 
Bucklandi (3 feet in diameter), Lima gigantea, Avicula, Gryphtea 
arcuata, Pentacrinites, &c., together with bones of Saurians ; a 
group that indicates the zone of Ammonites Bucklandi. 
The basement-beds of the Lower Lias (zone of Ammonites 
planorbis) are shown in Garden Cliff, to the south of Westbury- 
on-Severn ; and according to E. Witchell the beds have been 
opened up at Elmore. At Garden Cliff the section of the beds 
is as follows || : FT. IN. 
f Tumbled beds of grey earthy limestone and 
clay, with Ostrea liassica, &c. 
Lower Lias -^ Compact blue and grey limestone, with O. 
| liassica, Modiola minima, &c. - - 2 
[_ Brown marly shales - - 1 8 to 2 
,,., ( Smooth slaty limestone (Monotis Bed) with 
RhseticBeds-1. Monotis decussata - - --06 
* Trans. Geol. Soc. ser. 2, vol. i. p. 370. 
f The list given in Hull's Geol. Cheltenham, p. 1C, is wrongly stated to be from 
the " Bone Bed," and the occurrence of some of the species mentioned is exceedingly 
doubtful. 
% Quart. Journ. Sc. Lit. and Arts, N.S., 1830, p. 69. A shell (Zer/) discovered 
by K>. Ryder of Awre is here named Ryderia. 
Geology of Stroud, pp. 8, 9. See also Proc. Cotteswold Club, vol. iv. p. 56. 
1| See also Bristow and Etheridge, Vertical Sections (Geol. Survey), Sheet 46, 
No. 7. 
