Rockhall Wood Pit, Sutton
Also within
Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| TM304439 | — | Favourable | 5.3 | 2023-03-06 |
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 Period: Neogene, Quaternary
Landscape processes: Coastal
Description
Area, 5.4 ha. 13.3 ac. Description The pits at Rockhall Wood afford similar and excellent exposures of Pliocene Coralline Crag. They show a sequence from silty unleached sediment at the base to coarse bioclastic sediments from which the mineral aragonite has been removed by subaerial diagenesis post depositional chemical changes. This therefore, represents one of the only localities where the vertical sequence of diagenetic change can be seen. The fauna is rich and is most notable for the abundance of fragments of the bryozoan Metrarabdotos monilifera. These pits have been the subject of numerous studies. Monographs on the crag Mollusca have been based largely on collections made at this locality. A proposed sequence of zones approximating to time divisions for the Coralline Crag was based on the vertical sequence of sedimentological and palaeontological features here. Although much of the lower part of the sequence recognised in 1871 is now obscured, this site still presents the most varied and interesting vertical sequence of any Coralline Crag locality. In the study of Pliocene geology this is probably the most important site in Britain. This locality also shows Lower Pleistocene Red Crag banked up against a buried cliff cut into the Coralline Crag. Prestwich was able to demonstrate wave cut notches and derived boulders of Coralline Crag within the Red Crag sea proving that the inlier of Coralline Crag formed a knoll or reef in the Red Crag sea. Detached blocks of the Pliocene rocks showing boring and encrustation by barnacles. A key site showing a 'fossil' cliff line and demonstrating the erosive relationship between the Coralline and Red Crags.