These marks, visible from above as variations in crop growth, often indicate the presence of buried archaeological features beneath the soil. The site sits near the crown of a modest hill, occupying what would have been prime agricultural land; a detail that hints at the strategic importance this location may have held for its ancient inhabitants.

The enclosure was first spotted in an aerial survey photograph catalogued as St. Joseph, AVR 47, and represents one of many prehistoric sites scattered across Donegal's landscape. Such circular enclosures typically date from the Bronze Age through to the early medieval period, and could have served various purposes: defensive settlements, ceremonial spaces, or livestock corrals. Without excavation, the exact nature and date of this particular site remains tantalisingly uncertain.

This information comes from the comprehensive Archaeological Survey of County Donegal, compiled by Brian Lacey and his team in 1983. The survey documented field antiquities spanning from the Mesolithic period right through to the 17th century, creating an invaluable record of the county's rich archaeological heritage. Though the original entry dates back decades, the site at Carricknamanna continues to intrigue researchers and heritage enthusiasts alike, standing as a reminder of the hidden histories that lie just beneath Ireland's pastoral landscapes.