For most of the year it is invisible, folded into the ordinary surface of farmland on a south-facing slope, with a small stream running to the southwest. It takes cultivation to reveal it, and even then it looks, to the uninitiated eye, like little more than scorched debris.

What lies beneath is almost certainly a fulacht fiadh, the Irish term for a type of Bronze Age cooking or heating site found in enormous numbers across Ireland and Britain. The typical arrangement involves a trough, usually timber-lined or cut into the ground, filled with water, which was then heated by dropping fire-cracked stones into it. Once used, the stones were discarded into a mound nearby, and it is precisely this accumulation, of shattered, heat-stressed rock mixed with charcoal-blackened soil, that survives at Garryhasten. These sites tend to cluster near water sources, and the stream roughly 150 metres to the southwest fits the pattern well. A further point of interest is the proximity of an enclosure recorded about 40 metres to the northwest, suggesting that this particular patch of landscape saw repeated or varied use in prehistory, rather than a single isolated episode.