The Corndon flagstone quarries are on the South Western slopes of Corndon Hill and date from Medieval times. From the air the quarries are still a prominent feature in the landscape. In this area the altered Hope Shales of the Ordovician period on the margin of the dolerite produce finely laminated flagstones which were widely used on building on the Shropshire-Montgomeryshire border. Only a few buildings still have the flagstones as roofing slates, including the Old Post Office at Churchstoke and the porch to Hurdley Farmhouse.