Porthloo
Also within
Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| SV907115 | — | Favourable | 0.82 | 2023-01-13 |
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
Geological Feature: Raised Beach · Geological Period: Quaternary · Rock Type: Breccia
Landscape processes: Coastal
Description
Description Exposures of Quaternary sediments in the cliffs at Porthloo comprise, from the base upwards, a succession of raised beach deposits, organic silts and sands, head deposits and a capping layer of loess. This sequence shows changes in the climates and environments of the Quaternary Period ranging from storm beaches deposited during the Ipswichian Interglacial through to the Late Devensian loess sheets. In particular, the site is noted for the extensive and well developed brecciated head deposits which have made it the recognised type locality for the Porthloo Breccia. Analysis of organic deposits located in pockets within the Porthloo Breccia have yielded Late Devensian radio-carbon dates around 30,000 years before present. Analysis of pollen remains within the organic layer is indicative of arctic tundra conditions providing insight into the palaeoclimate at this time. The aeolian loess deposit which caps the sequence has been dated to around 18,000 years before present. These dates provide an important time constraint on the rate of environmental change in the south west of England during this period. Porthloo is also important for the lithostratigraphic evidence which the sediments represent and the sequence from this site is used widely in comparison with others on the Isles of Scilly.