In the southwest , around Bantry Bay and the mountains of Macgillicuddy 's Reeks , is an area of substantially deformed , but only 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 have well @-@ developed karst features . Significant stratiform lead @-@ zinc mineralisation is found in the limestones around Silvermines and Tynagh .