Llanelly Formation [Whitehead Limestone]
Early Carboniferous (Arundian)
PERIOD |
GROUP |
FORMATION |
Carboniferous |
Carboniferous Limestone |
Llanelly Formation |
Lithology
Thinly bedded, pale grey calcite and dolomite mudstones, commonly called 'chinastones'. with thin, interbedded, dark grey and brown shales. The calcite and dolomite mudstones weather whitish grey/buff. They are poorly fossiliferous except for some foraminifera, stromatilitic algae and occasional serpulid worms (Green, 1992).
Upper Boundary
The top is a sharp unconformity at which the topmost green-red mottled clay palaeosol is overlain by coarse sandstone of the Cromhall Sandstone.
Lower Boundary
The base is placed at a distinctive disconformity above the underlying Gully Oolite (Crease Limestone), above the rich iron bearing rocks of the Forest of Dean District. Locally, an angular unconformity is apparent, sometimes referred to as the
'mid-Avonian break' (Green, 1992).
Representative Sites
Tintern Quarry
Scully Grove Quarry
Information on lithology and boundaries taken from the British Geological Survey Lexicon of Named Rock Units
and BGS Memoirs. |
