Bass Rock - Geography and Geology

Geography and Geology

The island is a volcanic plug of phonolitic trachyte rock of Carboniferous (Dinantian) age. The rock was first recognised as an igneous intrusion by James Hutton, while Hugh Miller visited in 1847 and wrote about the Rock's geology in his book Edinburgh and its Neighbourhood, Geological and Historical: with The Geology of the Bass Rock.

The Bass Rock stands over 100 m high in the Firth of Forth Islands Special Protection Area which covers some, but not all of the islands in the inner and outer Firth. The Bass Rock is a Site of Special Scientific Interest in its own right, due to its gannet colony. It is sometimes called "the Ailsa Craig of the East". It is of a similar geological form to nearby North Berwick Law, a hill on the mainland. There are a couple of related volcanic formations within nearby Edinburgh, namely Arthur's Seat and Castle Rock.

Much of the island is surrounded by steep cliffs and rocks, with a slope facing south south west which inclines at a steep angle.

The Bass does not occupy the skyline of the Firth quite as much as its equivalent in the Clyde, Ailsa Craig, but it can be seen from much of southern and eastern Fife, most of East Lothian, and high points in the Lothians and Borders, such as Arthur's Seat, and the Lammermuir.