The only way to know this earthwork exists at all is to look down from the sky, and even then, it disappears depending on the year and the season. That kind of elusiveness is not unusual for the Irish archaeological record, but it gives this particular patch of pasture near Coolalough an oddly compelling quality.

The site was first picked out during the Bruff aerial photographic survey of 1986, when two linear cropmarks running parallel to each other were recorded in the survey notes as reference Bruff 71, AP 5/2077. Cropmarks form when buried features, whether ditches, walls, or banks, affect the growth of crops or grass above them; soil over a filled-in ditch tends to retain more moisture, producing lusher, darker vegetation, while compacted ground does the opposite. The parallel lines seen in 1986 suggested some kind of structured earthwork beneath the surface, lying approximately 115 metres east of the townland boundary with Kilfrush and around 110 metres to the southwest of a second possible earthwork recorded nearby. By the time Digital Globe orthoimagery was captured between 2011 and 2013, nothing at all was visible on the ground. Then, on a Google Earth image dated 14 September 2019, a faint oval-shaped cropmark reappeared, measuring roughly 13 metres northwest to southeast and 17 metres northeast to southwest. The same buried feature, readable one decade and invisible the next, depending entirely on rainfall, soil conditions, and the timing of the photograph.

There is nothing to see at Coolalough in the conventional sense. The site sits in ordinary pasture, and no surface trace of any monument survives. A visitor walking the field today would find only grass. What makes it worth knowing about is precisely that absence; the monument exists almost entirely as data, a set of coordinates, a pair of aerial images taken decades apart, and a classification held provisionally open by the question mark implied in the word "possible." For anyone interested in how the Irish archaeological survey actually works, this entry compiled by Fiona Rooney and uploaded in June 2021 is a useful case study in what counts as evidence when the ground itself refuses to cooperate.