Rubh' an Eireannaich
Also within
Condition (NatureScot)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| F1 | Tertiary Igneous | Favourable | — | 2009-10-29 |
Climate exposure
This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.
Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.
Geology & landscape
Geological Period: Jurassic, Paleogene · Rock Type: Basalt
Landscape processes: Coastal, Volcanic / Igneous
Description
Rubh' an Eireannaich Rubh’ an Eireannaich Site of Special Scientific Interest (SSSI) is located on the coast about 1.5 km north-west of Broadford on the Isle of Skye. The site contains an exceptionally well exposed example of a Palaeogene age composite sill, intruded into the surrounding Jurassic age sedimentary country rock. The sill at Rubh’ an Eireannaich is of particular interest because the mixing of both acid and basic magmas is demonstrated by an almost continuous gradation from basalt at the sill margins through to the felsite core, with hybrid zones between. Although the basic and acidic magmas comprising the sill were injected separately, the initial injection of basic magma was followed by the injection of the acidic magma before the basic magma had cooled and consolidated. Geochemical studies have shown that the two magma types are cogenetic (i.e. derived from a common parent magma). The relatively smooth geochemical variation inwards from the sill margin is attributed to an ionic diffusion process occurring in situ, but while both magmas were close to melting temperature. This provides evidence for the coexistence of basic and acid magmas. These results have important implications for the study of mixed acid-basic rocks elsewhere in the Palaeogene Igneous Province.