Goat Fell seen in the distance, on the other side of Broddick Bay
(Broddick is from the Norse for broad bay).

The island of Arran is an excellent place for both serious and hobby geology.  Arran
has examples of many classic geological features from most of the geological
episodes to have affected the British Isles.  The Island is characterised by a
rugged, hilly northern half, including the mountain of Goat Fell (Arran is Gaelic
for 'peaked island'), separated from a gentle, lower lying southern half
by the Highland Boundary Fault.

Examples of mineralisation, sediment deposition from past and present
environments, igneous intrusions, trace fossils, major structures (including
Hutton's Unconformity) and evidence of glaciation are among the
features present on this island.

Arran is about twenty miles long (north to south), located off to the
west of the port of Ardrossan on the west coast of Scotland.  The
wide variations in scenery and habitats have earned the island
the nickname of 'Scotland in Miniature.

Cloudy weather over Goat Fell

Holy Island in Lamlash Bay, site of a Buddhist retreat.
Caves on this island contain viking inscriptions.

Broddick Bay

Clauchland's Sill

Clauchland's Sill consists of cryptocrystalline Pitchstone (similar to obsidian).


Corrie, one of many glacial features on Arran.  There are also post-
glacial raised beaches and U-shaped valleys.

A composite basalt dyke.  One of many in the Tertiary
dyke swarm at Kildonan.

Glacial erratics.

The baryte vein, pictured here at the one point it outcrops at the
surface; in the river Sannox.

Old baryte mines at Glen Sannox, above the village of Sannox.

The mines follow a baryte vein in a line.  The mines themselves
are near-vertical and extremely dangerous, but specimens may
be found on the spoil tips.  There is at least one horizontal
mine tunnel towards the top of this hill, which should also be
considered dangerous.  While at Glen Sannox I found specimens
of baryte showing excellent reticulate habit.


The impressive U-shaped valley at Glen Sannox, another glacial relic.

The dipping line being pointed out on the rocks in the
mid-distance is the famous Hutton's Unconformity.  Seaward
dipping Old Red Sandstone overlays landward dipping Dalradian
Phillites.  Do get your photo taken here and do not hammer.
Grid ref: NR 932516

The island bird sanctuary of Ailsa Craig is the volcanic plug remnant
of a past volcano, seen here from Kildonan, south coast of Arran.
It is composed of distinctive Riebeckite trachyte (a type of granite).
Glacial erratics of this distinctive rock from Ailsa Craig may be found on
the east coast of Ireland and west coast of England and Wales.

A basaltic igneous dyke from the Tertiary Dyke Swam
is present in the foreground.

You may see seals off the small island of Pladda.  Pladda itself is
shaped by a dipping dolerite sill.  The coast of Ireland may also
be seen from Kildonan on a clear day.

An igneous dyke on the Corrie shore.  Basic igneous dykes exposed
to the sea are often eroded faster than the country rock.
(Incidentally, the person in this photo is Matthew Martin
of ScienceCentral.net).

Dessication cracks in mud.

Neptunian Dyke on the Corrie shore.

A pedestal rock.

The Machrie Moor Standing Stones

There are also a few sites of archaeological importance including the
Castle at Lochranza and the bronze age henge above.
At Blackwaterfoot King's Cave is said to be the site where Robert
the Bruce was inspired by the struggling spider.  The cave are marked
with graffiti of different ages, some of which is itself of archaeological
interest.  Collumnar jointing may be seen in the basalt cliffs.

Sunset over Arran, seen from the departing ferry.

Back to Top