Valley"), the great plain of Scotland stretching for 100 m. (5 to 10 m. broad), in a north-easterly direction from Dumbartonshire to Stonehaven, in Kincardineshire, between the great mountain barrier of the Highlands, the Grampians, and the Southern Lennox, Ochil, and Sidlaw Hills; in a more restricted sense denotes the plain between Perth and Brechin.