Dechmont Hill, situated in the parish of Cambuslang, was a place where our forefathers lighted the Beltane [fire]. In the Statistical Account of Scotland (1848) it is stated that a thick stratum of charcoal was discovered underneath a structure of fine loam on the summit of the hill. When the country people saw it they expressed no surprise, as the tradition was familiar to them that it was here where the former inhabitants of the country had been in the habit of lighting their Beltane.
From 'Old Scottish Customs' by E J Guthrie (1885). I can't see the story in the Statistical Account, though I could be looking in the wrong place.