Caithness has a stark simplicity to its scenery. An elevated plain stretches to far horizons of beckoning hills. Turn around and castellated cliffs drop sheer to the North Sea or Pentland Firth. A saga of great lakes, deserts and early life is hidden from view, locked in the Old Red Sandstone beneath our feet, muted by the peat of The Flows.

Caithness attracted the attention of many great Scottish geologists in the 19th century – and it still deserves our interest today. The landscape has been fashioned from sandstone by rivers, glaciers and waves over deep timescales. We find vestiges of Devonian mountains buried beneath ancient scree. An uplifted plain, raised before the Ice Age, and shaped by weather and streams before scouring beneath a succession of great ice sheets. And a vigorous coast, responding to shifting sea levels and retreating after each high energy storm. And more recently the slow millimetric growth of peat year on year for a thousand years. So many earth histories to explore.

Geology and scenery

The influence of rock type and structure is everywhere apparent than in Caithness. The county exhibits two basic terrains:

  • the plain of Caithness, with its gentle slopes, low hills and smooth ridges streamlined by glacial erosion
  • the hilly relief to the south and west, including isolated hills and ridges plus extensive peat-covered plateau, and displaying few signs of glacial modification.

The plain is developed across Devonian flagstones and sandstones. The dips of the Old Red Sandstone are low and control the gradient and form of the many gentle slopes. The rock is easily quarried by glacier ice or by waves, but its matrix of silt and sand is compact and strongly cemented, making for a durable rock. Coastal cliffs and platforms show strongly geometric outlines, with cliff faces often following the rock strike and geos exploiting major joints, or faults and igneous dykes.

The inselbergs (island mountains) of Maiden Pap and Scaraben are developed in resistant conglomerates and quartzites. Parts of this terrain are very old, exhumed by erosion in recent geological time from beneath hundreds of metres the Old Red sandstone cover rocks. On parts of Scaraben, lithified 380 million year old scree still clings to ancient hill slopes. The Langwell Forest covers a sequence of ridges and valleys that emerged gradually following uplift and tilting of Scotland towards the Norh Sea some 60 million years ago. The ridges follow resistant bands of quartzite and the valleys have been opened out in more easily weathered igneous and metamorphic rocks. The hill country of the north coast has knuckles of conglomerate and granite rising out of the peat-covered low ground formed in diorite and sandstone. It has been heavily moulded by the ice sheets moving northwards into the Moray Firth. The remote plateaux at the heads of the Dunbeath and Glutt waters are peat-covered remnants of erosion surfaces created by prolonged weathering and erosion before the Ice Age.

Main image on top: Coast of Duncansby Head, Duncansby Stacks (Envato elements _SXDKY8CZR2)

About this site

This site is concerned with the physical landscapes of Caithness. A great deal of technical material is available that deals with the natural history of the county but the level of awareness concerning the geology and geomorphology is often limited. The Bulletins of the Caithness Field Club are an important source of local information and the old Geological Survey Memoir remains a mine of useful observations.

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