Sully Island

Also within

South Glamorgan County

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Geology & landscape

Geological Period: Carboniferous, Triassic · Rock Type: Carboniferous Limestone, Limestone, Mudstone

Landscape processes: Coastal

Birds & fish recorded

Birds

Description

Description The excellent sea-cliff exposures of Sully Island provide sections in the marginal facies of the Triassic Mercia Mudstone Group. These rocks include a series of breccias and sands, interpreted as lake-shore deposits which are overlain by nodular evaporites and carbonates. They are all underlain (unconformably) by a terraced surface of Carboniferous Limestone. This site therefore demonstrates the regionally significant unconformity between Carboniferous and Triassic rocks, as well as a range of sediments, facilitating study of the lake facies and palaeoenvironments prevalent in late Triassic times. Sully Island additionally provides the main roost site for waders feeding in winter in the Taff/Ely Estuary. The roost holds up to 100%, of the dunlin, grey plover and ringed plover of the Taff/Ely and over 50%, of the redshank and knot. The Taff-Sully system is a nationally important site for dunlin and redshank supporting over 17 of the British wintering populations of these species. The Taff-Sully system also constitutes an important part of the wider Severn Estuary which is an internationally important wintering area for redshank, knot and dunlin.

Species mentioned