Yesnaby Sandstone Group

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Yesnaby Sandstone Group
Stratigraphic range: Givetian (Devonian)
Type Group
Unit of Old Red Sandstone Supergroup
Sub-units Qui Ayre Sandstone Formation, Harra Ebb Sandstone Formation
Underlies Caithness Flagstone Group
Overlies unconformable on 'basement'
Primary sandstone
Other siltstone, conglomerate
Region Orkney
Country Scotland
Extent west coast of Mainland, Orkney
Type section
Named for Yesnaby
Dune cross-bedded aeolian Yesnaby Sandstone exposed in the cliffs at Yesnaby and on Yesnaby Castle sea stack

The Yesnaby Sandstone Group is a Devonian lithostratigraphic group (a sequence of rock strata) in west Mainland Orkney, Scotland. The name is derived from the locality of Yesnaby where the strata are exposed in coastal cliffs.[1]


These strata are only exposed on either side of the Garthna Geo Fault in the Yesnaby area of west Mainland, Orkney.

Lithology and stratigraphy

The Group comprises the Qui Ayre Sandstone Formation and the Harra Ebb Sandstone Formation. The basal beds are talus and alluvial fan facies deposited in a fluvial or lake marginal environment probably during the Emsian Stage of the Devonian Period.[2]


  1. (BGS on-line lexicon of rock units)
  2. British Geological Survey 1:100,000 scale geological map (Scotland) Orkney Islands (special sheet)

External links