Potassium-argon ages of some Dalradian, Moine and related Scottish rocks

Abstract
Synopsis: New potassium-argon ages on Moine schists from north and central Sutherland are in general agreement with the age of 415–420 million years already found to be characteristic of the Moine outcrop. A similar age has been obtained on an F 3 pegmatite from the Loch Monar area and a Lewisian pelite, with F 3 crumples, from Loch Hourn. Dalradian specimens from Perthshire and Banff-shire show a spread of ages from 471 to 420 million years and are interpreted as overprints of a pre-Arenig metamorphism.