But at Farranreagh, near the small town of Knightstown, the remains of the island's slate works represent a quieter and older kind of industry, one that shaped the built fabric of the region long before any undersea cable was laid.

The site dates to the post-1700 period, placing it within the era of organised commercial quarrying that expanded across Ireland as demand grew for roofing and building materials in towns and estates. Valentia slate, a fine-grained metamorphic rock formed under enormous pressure over millions of years, was quarried and worked here into usable slabs and tiles. The term "slate works" points to more than simple extraction; it implies on-site processing, where raw stone was split, trimmed, and prepared before being moved on by sea. Knightstown's position as a small harbour settlement would have made that export practical, with boats able to carry finished slate to buyers along the Irish coast and beyond.