Portmuck ASSI

Portmuck contains the best exposure of the Cretaceous Hibernian formation in Northern Ireland, the only occurrence of the mineral sodalite in Ireland and the international type locality of Gobbinsite. A range of other minerals and basalt related features are also present.

The tombolo (a bar that extends outward from the shore, connecting with an island) between Isle of Muck and the mainland is the only such feature on the open coast of Northern Ireland.

A range of features associated with formerly higher sealevels are also present.

A range of typical seacliff communities are present together with limited saltmarsh and calcareous grassland.

A notable population of breeding seabirds including razorbill, guillemot, puffin, kittiwake and fulmar.