 It is unusually sinuous, being an incised meandering river valley very little altered by glaciers.The landscape of the Monadh Liath is one of the most ancient in Britain, its essentials as a secondary massif flanking the Cairngorms having evolved continuously since the Caledonian Mountains were created over 400 million years ago.Thus the land surface still slopes gently northwest towards the Great Glen, away from the main Grampian divide which crosses the Cairngorms.