Lewis and Harris MacLeod, and those on Lewis being referred to as from the clan MacLeod of Lewis. Lewis is also the ancestral home of Clan Morrison. The Lewis chessmen is a famous collection of 12th-century chess pieces, carved from walrus ivory and mostly in the form of human figures, which were discovered in Uig in 1831. A major industry on the island is the production of Harris tweed fabric, which is handmade on the island; by law only fabric produced in the Outer Hebrides can be called Harris tweed. The Lewis Trilogy of novels ("The Blackhouse", "The Lewis Man" and "The Chessmen")
Donegal batholith Dalradian and the granodiorite. These early phases were followed by the emplacement of a large volume of porphyritic monzogranites at a time when the granodiorite and tonalite had cooled sufficiently to fracture. This pluton lies at the southwestern end of the Main Donegal granite. Three distinct types of granite are recognised, an outer biotite monzogranite inside which there is a body of biotite-muscovite monzogranite and in the centre is an aplitic biotite-muscovite microgranite. The intrusion is interpreted to have the form of a laccolith. The main part of the pluton shows only weak evidence of deformation. Studies of the anisotropy