When crops grow unevenly over buried features, the differences in soil moisture and depth cause variations in plant height and colour that trace the outlines of ancient structures below. It is through precisely this effect that the ringfort at Cotts makes itself known, its circular form emerging as a cropmark on aerial photographs rather than as anything a ground-level visitor might readily notice.

What the photographs reveal is a bivallate enclosure, meaning a ringfort defined by two concentric banks and ditches rather than the single ring more commonly encountered. The inner diameter runs to approximately 35 metres, with the outer enclosure extending to around 55 metres across. A gap in both ditch features on the south-eastern side marks where an entrance once stood. Ringforts of this kind are generally associated with the early medieval period in Ireland, roughly the fifth to twelfth centuries, and were typically used as defended farmsteads by families of some local standing. The double-ring arrangement at Cotts suggests a site of slightly higher status than average, since the additional enclosure would have required considerably more labour to construct. The landscape around it is notably flat and low-lying, which may partly explain why no obvious surface trace has endured.