478 SECTIONAL TRANSACTIONS.—C. 
Province. ‘Thus Titterstone Clee, formerly part of the latter, was covered 
with Coal Measures of Midland facies. 
Dr. T. NEvILLE Grorce.—The Carboniferous shore-line in S. Wales. 
The general Armoricanoid trend of the South-Western Province was 
established in pre-Carboniferous times, and the Carboniferous sediments 
accumulated in an oscillating geosyncline to the south of St. George’s Land. 
Though generally the Lower Limestone Shales are conformable with the 
underlying O.R.S., they locally transgress, and probably overlap north- 
wards. Thus the shore-line at the commencement of the Carboniferous 
can be fixed, and its movements in Lower Avonian times deduced. 
The intra-Avonian unconformity, visible between the Vale of Neath and 
Kidwelly, indicates a southward retreat of the shore-line in C,S, times, 
followed by a re-advance, causing Sz beds to transgress probably down to 
the O.R.S. 
In D times the shore-line lay beyond the existing coalfield, though not 
far distant to the north. At the close of the Avonian, regional emergence 
accounts for the unconformity beneath the Millstone Grit; while the 
overlap of higher goniatite zones over lower ones suggests an embayment 
in the mid-portion of the North Crop between two southward-extending 
headlands. 
The east to west trend of the Armoricanoid axes was modified in places by 
transverse structures which had considerable effect upon sedimentation 
and coast-line configuration during the Carboniferous period. 
Dr. E. NEAVERSON. 
The Carboniferous Limestone of Flintshire and Denbighshire forms a 
fringe dipping off various zones of Lower Ludlow rocks which formed the 
Carboniferous land surface in this part of St. George’s Land. West of the 
Denbighshire Moors the great Ordovician tract of Snowdonia extends 
north into Anglesey. Carboniferous rocks occur in the eastern part of 
this island and on the southern shore of the Menai Strait. The ancient 
shore-line in North Wales is now modified by marginal faulting of com- 
paratively slight effect as a whole. 
The limestone often rests on a basement of red conglomerate and sand- 
stone containing water-worn boulders of older rocks. In Anglesey these 
are mainly pre-Cambrian and Ordovician rocks of local origin. Around 
the Denbighshire Moors the red beds contain abundant boulders of Upper 
Ludlow flagstone not known in situ in North Wales, but a former north- 
ward extension from the type-area is indicated. ‘The junction of basement 
beds and limestone corresponds approximately with the base of the Dibuno- 
phyllum zone, thus dating the Carboniferous transgression from the north. 
The Carboniferous Limestone is formed almost entirely of marine organic 
debris ; hence peneplanation of the adjacent land mass is inferred, or perhaps 
a cliffed plateau protected against marine abrasion by offshore shoaling. 
In the Vale of Clwyd the lithology of the D, limestones suggests a 
landlocked bay with slight tidal range. ‘There is some evidence of overlap 
at the southern end of the Vale, though nothing higher than D, occurs on 
the western side. The present Clwyd Range was possibly separated from 
the western massif in D, times, and there was probably an extension up the 
Dee Valley to Corwen in D, times. The occurrence of knoll-limestones 
in North Flintshire is noteworthy. 
In Flintshire the Holywell Shales have yielded marine faunas representing 
several goniatite zones. Above these are typical Coal Measures which 
