Around the bottom of the Knock, there is what appears to be a "causeway" of some kind. I first noticed it when me, Scotty and Martin visited here in 2002, and it was so flat that at first I thought it must have once carried a railway. However, checking the map shows that the only railway that used to run near here was south-west of Crieff and not north-east. Besides, the "causeway" is considerably wider than engineers would have built for a railway embankement.
It certainly appears to be too flat to be natural (unless it's perhaps a grass-covered lava flow from the Knock) and does have the look of having been made or modified by human hands. You can see parts of it in the photos I've posted.
It curves around the bottom of Kate McNieven's Craig, then heads off south-west along the edge of the rest of the Knock. Could it even be a cursus of some kind?