Halfway Quarry
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Climate exposure
This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.
Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.
Geology & landscape
Mining / Industrial: Quarry · Geological Period: Devonian · Rock Type: Sandstone
Landscape processes: Coastal
Description
Description This site is an important locality for stratigraphy and environments at the base of the lower Old Red Sandstones of Wales. It shows a sequence from Ludlow-age shallow marine sediments (Roman Camp Beds), via the sandstone-rich ‘Downtonian’ Long Quarry Beds of possible beach/barrier origin, into the basal Red Marls. The nature of the transition from Ludlow marine rocks to continental Red Marls in south-west Wales is controversial, with differing views on whether or not an unconformity exists at the base of the Long Quarry Bed. This is a key exposure showing a full sequence, important for the determination of the environments present, the history of this transition and for defining formal rock-stratigraphic units. The Ludlow-Downtonian Roman Camp Beds and Long Quarry Beds here contain the plant genera Thallomia, Cooksonia and Steganotheca. The Roman Camp Beds have yielded an axis of either Cooksonia or Steganotheca bearing in situ tracheids; incontrovertible evidence of the earliest vascular land plants. This occurrence is unique in pre-Devonian strata and it marks the site as a palaeobotanical locality of international importance.