When a hachured feature appeared on the 1926 revision of the six-inch OS map for Drinaun in County Galway, it suggested the presence of some kind of earthwork or depression worth recording. When the site was inspected in 1984, the feature turned out to be considerably more modest in origin: a disused sand pit, now visible only as a hollow in an area of rough grazing land.

Sand pits of this kind were common rural workings, typically dug to supply local needs for sand used in mortar, lime render, or general building work. The Drinaun example is thought to date from the nineteenth or early twentieth century, placing it within the long period of agricultural improvement and small-scale construction activity that reshaped much of the Irish countryside. Over time, such workings were simply abandoned when the resource was exhausted or no longer needed, leaving behind a shallow depression that grass and rough grazing gradually softened into the landscape.