This was recorded on the Northern Antiquarian website on their visit to the Ballachraggan chambered cairn near Callander. It is on a small platform of rock about 150m NE of the cairn on the side of a prominent knoll - ''two large cup-markings, with the more easterly one of the two seeming to have a carved arc along its edge.''
This was visited and recorded on 14/1/19 and appears to be natural. The local conglomerate rock contains rounded pebbles which weather out of the rock matrix leaving cup-like depressions. There are many examples of these natural 'cup marks' on rocks and on the numerous conglomerate boulders in this area
OS REFERENCE
NN 68174 06583