On an east-facing slope near Woodstown in County Waterford, a circular enclosure roughly 35 metres across exists in a state most archaeological sites never quite escape: it is visible only from the air, and even then only faintly, as a cropmark. Cropmarks form when buried features alter the growth of vegetation above them, causing subtle differences in colour or height that become legible in aerial photographs under the right conditions, typically a dry summer when soil moisture varies sharply over buried ditches or walls. What lies beneath the surface at Woodstown has not announced itself in stone or earthwork; it shows itself only as a whisper in a field.