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]
| Yesnaby Sandstone Group | |
|---|---|
| Stratigraphic range: Givetian (Devonian) | |
 Dune cross-bedded aeolian Yesnaby Sandstone exposed in the cliffs at Yesnaby and on Yesnaby Castle sea stack | |
| Type | Group |
| Unit of | Old Red Sandstone Supergroup |
| Sub-units | Qui Ayre Sandstone, Harra Ebb Sandstone |
| Underlies | Caithness Flagstone Group |
| Overlies | unconformable on 'basement' |
| Lithology | |
| Primary | Sandstone |
| Other | Siltstone, conglomerate |
| Location | |
| Region | Orkney |
| Country |  Scotland |
| Extent | West coast of Mainland, Orkney |
| Type section | |
| Named for | Yesnaby |
Outcrops
editThese strata are only exposed on either side of the Garthna Geo Fault in the Yesnaby area of west Mainland, Orkney.
Lithology and stratigraphy
editThe Group comprises the Qui Ayre Sandstone and the Harra Ebb Sandstone. 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]
References
edit- ^ British Geological Survey. "Yesnaby Sandstone Group". BGS Lexicon of Named Rock Units. Retrieved 20 March 2022.
- ^ British Geological Survey 1:100,000 scale geological map (Scotland) Orkney Islands (special sheet)
