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Earth Science Conservation Review
| Rosemount - site of local interest | Down |
| Site number: | 750 | ||
| Locality Type: | Quarry (disused) | Status: | local interest |
| Grid Reference: | J591675 Centroid | ||
| Google maps: | 54.5313,-5.54222 | ||
| County: | Down | Council area: | Ards & North Down Borough Council |
| Period: | Silurian | ||
| Stages: | Llandovery | ||
| Lithostrat: | Tullykevin Formation | ||
| Site Description | |
|---|---|
| Highlights: | |
The disused quarries at Rosemount provide good exposures of the Tullykevin Formation. These mostly argillaceous sediments contain interbedded horizons of greywacke displaying numerous sedimentary structures, which provide important indicators of younging direction in an otherwise monotonous argillaceous sequence. | |
| Description: | |
The Tullykevin Formation extends from Tullykevin townland southwest to Greyabbey. The disused quarries at Rosemount provide good exposures of the formation. The Tullykevin Formation is a predominantly argillaceous unit outcropping at the core of a northeast trending syncline which is overturned towards the northwest. Along its south-eastern limit, the Tullykevin Formation is apparently conformable with greywackes of the Strangford (Gala) Group whereas it appears to be in faulted contact with the Strangford Group to the northwest. These factors combine to make estimation of the thickness of the Tullykevin Formation difficult. At Rosemount the Tullykevin Formation consists of hard bluish-grey fissile mudstone, soft black micaceous mudstone and laminated siltstone. A very strong closely spaced regional cleavage (S1) is parallel or subparallel to bedding resulting in a rock which is easily split and which, in the past, was used locally as roofing material. Interbedded with the mudstones and siltstones are a few horizons of greywacke, generally 0.1-0.2m thick but up to 2m thick. These coarser-grained sediments contain sedimentary structures such as load-marks, loaded ripples and cross-laminations which provide important indicators of younging direction in an otherwise monotonous argillaceous sequence. One greywacke unit has, at its base, a thin intraformational breccia with an erosion surface, which cuts down into underlying siltstones. The total absence of fauna from the Tullykevin Formation makes dating the sequence difficult though it is probably of mid-late Llandovery age. | |
| Importance: | |
This site is of little value scientifically though the greywacke horizons do provide important evidence of younging in an otherwise monotonous argillaceous sequence. The exposures at Rosemount are of significant educational value as they provide good exposures of several sedimentary rock types, sedimentary structures and younging indicators. As such, the site would be of value to second and third-level students as well as to amateur groups and societies. | |
| Notes: | |
The fissile rock at Rosemount was quarried in the past for use as a local roofing material. | |
| Keywords | |
|---|---|
| Rocks: | Greywacke, Mudstone, Siltstone |
| Structures: | bedding, cross-bedding, ripple marks, cleavage, load marks |
| Access | |
|---|---|
| Approach: | This site comprises disused quarries 1km southeast of Greyabbey. |
| Uses | |
| Educ. Level: | The exposures at Rosemount are of significant educational value to second and third-level students as well as to amateur groups and societies. |
| Record type: | SLNCI Report | ||
| Entered by: | E M Porter | ||
| Last updated: | 09/10/03 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Rosemount - site of local interest, County Down, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=750. Accessed on 2026-11-08. |
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