In a tillage field near Grange in County Wicklow, the faint outline of what may be an ancient field system is detectable not on the ground at all, but as a cropmark visible in aerial photography. Cropmarks form when buried features such as ditches, walls, or banks affect how plants grow above them; soil over a filled-in ditch tends to retain more moisture, producing lusher, taller crops, while compacted or stony ground beneath a former wall produces the opposite effect. The result, when conditions are right and the angle of light favourable, is a ghostly pattern pressed into the surface of an ordinary working field.

The site at Grange came to notice through aerial photographs taken by M. Moore in July 2006. The images show only faint traces, and the identification remains cautious, described as a possible field system rather than a confirmed one. That tentativeness is itself telling. Field systems of this kind can date from any period, prehistoric through medieval, and without excavation it is rarely possible to say more than that something organised the land here once, in lines and boundaries that the plough has not entirely erased.