Others exist only as faint signatures in the soil, visible not to the eye on the ground but to a camera looking straight down from altitude. At Spittle in County Limerick, a small circular ditch-barrow roughly six metres in diameter sits quietly beneath pasture, betraying almost nothing of its presence to anyone walking across it.

A ditch-barrow is a burial monument, typically prehistoric in origin, consisting of a low central mound or platform encircled by a cut ditch. Over centuries of ploughing, grazing, and general agricultural use, the upstanding elements of such monuments are often completely levelled, leaving only the ditch itself as a subsurface trace. That buried ditch, cut into subsoil of a different composition to the surrounding ground, holds moisture differently to the undisturbed earth around it, and in dry conditions the grass or crops above it grow at a slightly different rate. The result is a cropmark, a tonal variation in vegetation that becomes legible only from above and only under the right conditions. The Spittle example was recorded by Caimin O'Brien from a Google Earth orthophoto taken on the 18th of November 2018, and uploaded to record in December 2021. At approximately six metres in diameter, it is a modest monument even by the standards of the type.

Because this site survives only as a subsurface feature within grassland, there is nothing visible at ground level to seek out. The most useful way to observe it is through the Google Earth orthoimages attached to the record, which show the circular cropmark clearly against the surrounding pasture. For anyone with an interest in landscape archaeology or aerial survey, the image itself is the object of interest here, demonstrating how much of Ireland's prehistoric past persists invisibly underfoot, legible only when the season, the weather, and the angle of a satellite camera happen to align.