A cairn, in its simplest form, is a deliberate mound of stones raised by human hands, most often in prehistoric times to mark a burial, a territorial limit, or simply a prominent point on the landscape. These two have endured long enough to become part of the terrain.

The cairn on Little Carron is the more substantial of the pair. It measures roughly 14 metres east to west and 11.6 metres north to south, rises to a height of about 1.64 metres, and has noticeably steep sides, giving it a compact, purposeful appearance rather than the low spread of a natural scree accumulation. Its surface is partially covered with grass and heather, as upland cairns tend to become over the centuries when left undisturbed. The second cairn, a little further to the west-southwest on the flatter top of Carron Mountain, is smaller and more eroded, with a diameter of around 5 metres across its surviving top. What makes their setting particularly interesting is the county boundary itself. Five other mounds are marked along the same boundary on older Ordnance Survey maps, but these have been identified as recent in origin, which throws the genuinely ancient character of these two into sharper relief. The boundary line may well follow a much older division in the landscape, one that prehistoric communities recognised long before any administrative map was drawn.