100 i LI AS OF ENGLAND AND WALES : 
Lower Lias ; while Prof. P. M. Duncan* adopted a sort of compromise by 
employing the term Infra-Lias, which includes both White Lias (Rhaetic Beds) 
and the zones of A. planorbis and A. angulatus. 
Bristow, who maintained that the beds belonged to the Lower Lias, disputed 
the sequence pointed out by Tawney, urging that there was but one series, by 
whatever name it may be called ; the Southerndown Series being merely the 
easterly prolongation and the representative of the Sutton Stone, and the 
total thickness being from 35 to 37 feet. Readmitted, however, that as the 
Sutton Stone reposes on the upturned edges of the Carboniferous Limestone, 
'and fills up irregularities and undulations in that rock, the thickness is some- 
what variable in different places. 
Subsequently Tawney abandoned his view on the Rhsetic age of the deposits, 
and for a time the question appeared to be settled. In 1884, however, 
Mr. Tomes expressed his conviction that the conglomerate-bed at Stormy 
Down near Bridgend "is the true representative of the Sutton Stone of 
Sutton, and West of the 'Guinea' bed of Binton and Grafton in War- 
wickshire, and of the White Lias of that county and the West of 
England ";f a view taken also by Mr. W. C. Lucy,{ who had accompanied 
Mr. Tomes on a visit to the South Wales district. At the same time 
Mr. Etheridge, who had previously considered that the Sutton Stone and 
white conglomerate might be of Rhaetic age, observed that their precise position 
was still an open question. 
No doubt some difficulty is experienced, in making out the 
precise relations of the white Sutton Stone and conglomerate, to 
the ordinary Lower Lias of this area. This arises in part from 
the cliffs being to a great extent inaccessible, while portions of the 
coast can only be visited for a short time when the tides are at 
their lowest ; and we have to scramble over ragged rocks. More- 
over the strata themselves are subject to variations, and are 
shifted in three or four places by faults, in situations where it is 
difficult to estimate the precise amount of the displacement. By 
measuring the strata in detail at several points, I was enabled in 
time to make out the sequence, and to satisfy myself that while 
the white Sutton stone and conglomerate (with occasional bluish 
modifications) form the base of the series, both at Sutton and 
Dunraven, these beds pass up insensibly into the blue and grey 
conglomeratic (Southerndown) beds, which are overlaid by the 
ordinary beds of the Lower Lias. The sequence, therefore, that 
was pointed out by Tawney is correct, although the Sutton Beds 
merge upwards into the Southerndown Series without any definite 
plane of demarcation, (See Fig. 45.) The total thickness of the 
conglomeratic series, where it could be definitely measured, varies 
from 50 to 80 feet, but it increases still more in its western 
development between Sutton and Southerndown. 
The whole of these beds may be regarded as the basement- 
beds of the Lower Lias, representing the Ostrea-beds and 
other portions of the zone of Ammonites planorbis, and including 
perhaps portions of the zone of A. angulatus. They are overlaid 
conformably by limestones and shales exhibiting the ordinary 
characters of Lower Lias, and belonging partly to the zone of 
A. angulatus, but mainly to that of A. Bucklandi. 
* Quart. Journ. Geol. Soc., vol. xxii. p. 89 ; vol. xxiii. p. 15 ; vol. xlii. pp. 101, 
113, 139 ; and Supp. to Fossil Corals, Palseontogr. Soc. 
f Quart. Journ. Geol. Soc., Tol. xl. pp. 353, 359 ; see also vol. xxxviii. p. 411. 
J Proc. Cottes-w. Club,TOl. viii. p. 254. 
Quart. Journ. Geol. Soc., rol. xl. p. 875 ; see also Proc. Cardiff Nat. Soc., 
vol. iii. pp. 89-62. 
