The Cockburn Law intrusion, Scotland, is composed of a core of adamellite surrounded by granite, which constitutes the major part of the intrusion, granophyric microgranite, which forms the cover and marginal zones of the uncontaminated igneous material, and hybrid diorites, which form the periphery of the whole intrusion. The age of the intrusion is late Caledonian, and its emplacement probably took place during the lower Old Red Sandstone period (Devonian).