This moated site at Island Upper first appeared on the 1839 Ordnance Survey map as a circular embanked enclosure within a rectangular wooded area, measuring roughly 35 metres square. By 1940, surveyors recorded it as a subrectangular platform enclosed by substantial earthen banks; these ramparts stood between 1.5 and 3 metres wide, rising about 0.8 metres on the interior and an impressive 1.5 to 2 metres on the exterior, though notably lacking any defensive ditch or fosse at that time.

Today, whilst the earthwork remains invisible at ground level beneath the pasture, modern technology has revealed what the naked eye cannot see. Google Earth imagery from 2018, first spotted by researcher Simon Dowling, shows the site as a distinct cropmark; a rectangular enclosure measuring approximately 38 metres north-northwest to south-southeast by 36 metres east-northeast to west-southwest, now clearly defined by fosses or moats about 2 metres wide. Interestingly, local descriptions from 1987 mentioned the site as a raised rectangular area with a fosse, suggesting the defensive ditches were either always present but overlooked in the 1940 survey, or had become more pronounced through agricultural activity over time.

The site’s position on a slight rise about 370 metres southwest of the River Lask follows the typical pattern of Anglo-Norman moated sites in Ireland, which were often built as defended farmsteads or manor houses during the medieval period. These earthworks served both practical and symbolic purposes; providing drainage on low-lying ground, defence against raids, and a visible statement of authority in the landscape. The Island Upper site’s evolution from wooded enclosure to pasture, and its transformation from clearly visible earthwork to hidden cropmark, tells a broader story of how Ireland’s medieval landscape has been gradually absorbed into modern farmland, with many such sites only revealing themselves through aerial photography or particularly dry summers.