Geikie's (1887) section of Morven, showing Devonian conglomerate and sandstone resting on an ancient landsurface developed across upturned Moine schist
Morven from the north, with the quartzite Small Mount behind
Image by Alan Moar
A glacial erratic boulder of Devonian quartzite breccia. East top of Scraben
Definition: an ancient terrain which has re-emerged due to the erosion of the sedimentary rocks that once covered it
Along the western fringes of Caithness, the cover of Devonian flagstones and sandstones thins and basement rocks emerge. The land surface developed on the basement has been partly remodelled by glacial and preglacial erosion but it remains substantially in the same form as existed 380 million years ago prior to its burial in the Devonian.
West of Reay, the sub-Devonian surface is dominated by craggy hills but in the basin of the Dunbeath Water the terrain is much smoother, a reflection of the propensity towards breakdown of some of the granitic rocks. The most spectacular ancient slopes are those on the northern flanks of Scaraben. Here ancient lithified scree clings in patches to the hill slope and demonstrates that this is the flank of the a Devonian mountain. Its summit, though, is now lost to erosion.