The geology of the island is an epitome of that of Scotland. The mountains of the north, especially Goatfell, consist of granite, surrounded on the flanks by micaceous and argillaceous slates; lying on the edges of the slate are well seen red sandstone and conglomerate, especially on the eastern shores, but easily traceable across the island. On the eastern side limestone, containing Carboniferous fossils, is found at several points intercalated among the red sandstones chiefly at Corrie, where several strata divided by shale are quarried. In the southern part of the island the stratified formations^are overlain by a great series of trap-rocks. Several beds of coal were formerly worked on the northeast coast. This coal lies low down in the Carboniferous series, at the base of the Carboniferous limestone, or in the “calciferous sandstones.” Numerous veins of most beautiful pitchstone and pitchstone-porphyry traverse the red sandstone, especially at Drimadoon and between Brodick and Lamlash. On the mountains are found jasper, agates, cairngorms, and small clear specimens of rock-crystal, called the Arran diamond.

A considerable manufacture of sulphate of baryta as a pigment was at one time carried on in Glen Sannox. The herring fishery is prosecuted by the islanders. Arran possesses two reftarkably fine natural harbours,—Lamlash Bay, on the south-east of the island, and Loch Ranza on the north-west side. The latter is an indentation of the sea on the north of the island, about a mile in length, and is a place of great resort for 1 boats engaged in the herring fishing. The ruins of an old castle stand upon a small peninsula near the entrance. Almost the whole island belongs to the duke of Hamilton, whose seat is at Brodick Castle. The landing-pier for steamers and the principal hotel are at Brodick Bay, where there is a village with church and school. Six miles from Brodick lies the village of Lamlash. Its beautiful semicircular bay, sheltered by the Holy Island, forms an excellent harbour for ships of all sizes. The Holy Isle, an irregular cone 1020 feet high, was once the site of a cell inhabited by St Molios, a disciple of St Columba. Off the south-east point of Arran lies the low rocky islet of Pladda, with a lighthouse having two fixed lights 130 and 77 feet above high water, and visible 16 and 13 miles respectively, in clear weather. It has a telegraph station, from which the arrival of vessels in the Clyde is notified to Glasgow and Greenock. Many parts of the island are traditionally connected with Robert Bruce. Thus one of the largest of the water-worn recesses in the high sandstone cliffs of the west coast is called the king’s cave, another is the king’s kitchen, a third his cellar, and a fourth his table, while the hill above is the king’s hill; the southern extremity of Lamlash Bay is the King’s Cross Point; and an ancient fort in Glencloy is said to have sheltered his men.

The antiquities of the island, besides those already mentioned, are Druidical circles (of which the most complete are at Tormore, near Drimadoon, and are called Suidhe Choior Fhionn, or Fingal’s cauldron seat), Danish forts, and sepulchral cairns, such as the immense mound, 200 feet in circumference, at the head of Glen Meneadmar or Moneymore.