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Condition (NatureScot)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| F1 | Ordovician Igneous | Favourable | — | 2005-03-31 |
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: Ordovician
Landscape processes: Coastal, Volcanic / Igneous
Description
Virva Virva is on the west side of the Wick of Gruting, 2.5 km north-west of Funzie on Fetlar. Much of the island of Fetlar is composed of rocks belonging to an ophiolite complex. The Shetland Ophiolite, of Ordovician age, is composed of basic and ultrabasic igneous rocks believed to represent a dismembered section of ocean crust. The rocks were obducted into their present position as nappe structures. The Shetland ophiolite is one of only three examples of ophiolite in Scotland, and as such is of great interest in our understanding of the geological history of the country. The cliffs and cliff-top exposures immediately south of Virva expose the thrust junction between the basal harzburgites of the ophiolite nappe and the underlying metamorphic rocks. Metamorphic grade in the underlying schists decreases rapidly away from the contact over a distance of 100m to 200m. The decrease in grade is interpreted as representing an inverted dynamo-thermal aureole formed in the schists in response to emplacement of the overlying nappe. Inverted aureoles of this type have been described from ophiolite complexes throughout the world and the Virva locality provides one of the best examples in Shetland. This site is therefore of key importance in our understanding of the Shetland ophiolite.