Beneath that flatness, barely visible at ground level, lies the ghostly geometry of an old field system, a network of earthen banks so slight that you could walk across them without registering what they represent. What makes this particular landscape legible at all is the angle of view: it took an aircraft.

In August 1999, aerial reconnaissance by Markus Casey picked out a field system covering an area roughly 200 metres from northwest to southeast and 153 metres from east-northeast to west-southwest. The arrangement is organised around a central enclosure, a roughly bounded space from which four field banks radiate outward at the cardinal and diagonal compass points, northeast, southeast, southwest, and northwest. Field banks of this kind are low earthen boundaries, built up over time from cleared stone or turned soil, used to divide land for grazing or cultivation. Here they are exceptionally modest, rising only about 20 centimetres above the surrounding ground, and between 4 and 5 metres wide. Some run straight for short distances before turning, suggesting deliberate planning rather than gradual drift. One bank connecting two possible enclosures extends for 32 metres; another trails off eastward for 20 metres before disappearing entirely. Further out to the east and north, the traces become even fainter. A possible house site was also identified nearby, and a separate possible enclosure abuts the whole system to the north.

The date of the field system is not recorded, and without excavation it is difficult to say whether this represents medieval farming, post-medieval land use, or something older. What it does suggest is that Tawin Island, now sparsely inhabited, once carried a more organised agricultural life, parcelled out and tended in ways that left their mark just deeply enough to survive.