In the southwest, around Bantry Bay and the mountains of MacGillycuddy's Reeks, is an area of substantially deformed, lightly metamorphosed Devonian-aged rocks. This partial ring of hard rock geology is covered by a blanket of Carboniferous limestone over the centre of the country, giving rise to a comparatively fertile and lush landscape. The west-coast district of the Burren around Lisdoonvarna has well-developed karst features. Significant stratiform lead-zinc mineralisation is found in the limestones around Silvermines and Tynagh.