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Earth Science Conservation Review
| Benvan - Structural | Antrim |
| Site number: | 649 | ||
| Locality Type: | Crags, Inland exposure | Status: | ASSI |
| Grid Reference: | D205415 Centroid | ||
| Google maps: | 55.2063,-6.10721 | ||
| County: | Antrim | Council area: | Causeway Coast & Glens Borough Council |
| Period: | Precambrian | ||
| Stages: | Dalradian | ||
| Lithostrat: | Argyll Group, Owencam Formation, Crinan Subgroup | ||
| Site Description | |
|---|---|
| Introduction: | |
Benvan is an isolated site, located on exposed moorland between the southern end of Murlough Bay and the northern slopes of Greenanmore (282m OD). Access is via a farm track leading NW from Torr Road at [D194 405] (Fig. 16) or by scrambling up slopes from Murlough Bay. The site has significant structural interest and contains particularly good examples of the regionally dominant and locally penetrative cleavage (S2). | |
| Description: | |
The Benvan site consists of a series of crags defined by NW-SE orientated normal faults. Exposures are mainly of massive, coarse-grained feldspathic grit, and quartz schist (psammite) interbedded with quartz-mica schist (semipelite) with some pale green chloritic schist (greenbeds?). These beds form part of the Owencam Formation (Crinan Subgroup, Argyll Group, Middle Dalradian) and are amongst the oldest strata known in the NE Antrim Inlier. Structurally, the rocks at Benvan are located close to the core of the major recumbent anticline, which controls the regional structure. Most outcrops have a distinctive ribbed appearance, partly due to the development of thin, ribbon-like quartz segregations and boudins parallel to the regionally dominant and locally penetrative cleavage (S2). S2 dips at about 30°NW and is a spaced, strain-slip cleavage which crenulates the earlier composite fabric (S0S1). This composite fabric is particularly well developed in the gritty psammite and quartz-mica schist lithologies and involves bedding and an early formed pressure solution cleavage. Locally these intersecting cleavages impart a herring-bone appearance to the outcrops. The deformation described above was accompanied by relatively low-grade regional metamorphism and the rocks contain mineral assemblages indicative of the quartz-albite-muscovite-chlorite subfacies of the Greenschist Facies. | |
| Notes: | |
For general information on the Structural Geology of Northern Ireland, directions to other Structural Geology sites and an extensive reference list see Key Site 641 - Introduction to the Structural Geology of N. Ireland. See also Key Site 155 - Benvan [Precambrian Stratigraphic block]. | |
| Keywords | |
|---|---|
| Minerals: | Chlorite |
| Rocks: | Grit, Psammite, Schist |
| Structures: | anticline, boudinage, fault, cleavage |
| Access | |
|---|---|
| Approach: | Access is via a farm track leading NW from Torr Road at [D194 405] (Fig. 16) or by scrambling up slopes from Murlough Bay. |
| Record type: | ESCR report | Recorded by: | T.P. Johnston |
| Entered by: | E M Porter | ||
| Last updated: | 23/09/03 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Benvan - Structural, County Antrim, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=649. Accessed on 2026-11-05. |
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