Most of the highest ground is formed by the masses of granite which have been intruded into the Ordovician and Silurian rocks; the Criffel mass lies about Dalbeattie and Bengairn, another mass extends east and west between the Cairnsmore of Fleet and Loch Ken, another lies north-west and south-east between Loch Doon and Loch Dee and a small mass forms the Cairnsmore of Carsphairn. Much granite was quarried from Kirkmabreck, near Creetown for dock construction from 1830 on.