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Earth Science Conservation Review
| Attical Complex - Attical Valley Outwash | Down |
| Site number: | 462 | ||
| ESCC: | IS | ||
| Locality Type: | Inland exposure | Status: | TBC |
| Grid Reference: | J269193 Centroid | ||
| Google maps: | 54.10763,-6.05976 | ||
| County: | Down | Council area: | Newry, Mourne & Down District Council |
| Period: | Quaternary | ||
| Stages: | Late Midlandian | ||
| Site Description | |
|---|---|
| Description: | |
Outwash spreads are limited by the ridge dominated valley topography of the area. However, the southern end of the Pigeon Rock River valley contains very low relief (<1m) ridges and intervening flats. Sections in drainage channels cut into the flats expose stratified coarse gravel. BROWN PIT An exposure at Brown Hill (~20m x 2m) consists of stratified sand, gravel and diamict. Facies description Beds (<1m thick) of cross-bedded mainly fine sand and occasional pebble gravel dip towards the southeast (130°). Bed contacts are conformable and non-erosional. Bed surfaces are planar to rippled. A shallow channel (1.5m wide) contains cross-bedded sand. There is an erosional to non erosional contact with overlying discontinuous poorly sorted stratified granule to pebble gravel (<30cm) containing occasional cobbles. Beds (<8cm) are undulating with amalgamated contacts. Clasts are frequently imbricate, mostly with an a(t) fabric, dipping towards 340°. The contact with overlying crudely stratified diamict (<1m) is undulating, conformable and non-erosional. Diamict is matrix supported, clasts have a chaotic fabric, and stratification is emphasised by gravely bands and short cobble lines. A lens (1m wide and 15cm thick) consists of stratified well-sorted sand and granules. Granules are matrix to framework supported. A pod (70cm across) with a convex down lower surface consists of sorted gravel, grading from granule-pebble at the bottom to pebble to cobble at the top. Lower clasts have an a-axis horizontal preferred orientation, while upper clast orientation is chaotic. | |
| Interpretation: | |
Exposures at the Brown Hill pit (J269193), fronting a well-marked moraine ridge, record sedimentation in a moraine-ponded environment (cf. Shaw, 1973). Cross-bedded rippled sand and fine gravel record grain flow in low flow conditions (Church & Gilbert, 1975), and the channel records scour and fill. Overlying discontinuous stratified gravel reflects non-uniform sediment gravity flow down the distal ridge slope. Diamict records deposition from debris flows, with non-erosional bed boundaries, predominantly matrix support, and a generally disorganised fabric (Middleton & Hampton, 1976). The crudely sorted pod is interpreted as a flow nose. The well-sorted sand and granule lens records flow in a channel, with sediment bypass resulting in framework supported clasts. Undulating beds are the result of removal of support as ice withdrew. Subaqueous deposition at this site, subdued relief and flats at the entrance of the Pigeon Rock River valley, and a well-marked lake bed (J258222) record ponding during retreat of readvance ice. The largest water body within the valleys occupied Deers Meadow, with an area of ~2.5km2, based on the altitude of the shoreline notch. | |
| Notes: | |
For site specific information on other sites within the Attical Complex see the following site: Key Site 461 - Attical Complex - Attical Valley Moraines For overview information and references on the Attical Complex see the following site: Key Site 447 - Attical Complex, Mourne Mountains - Overview For overview and site specific information on other sand and gravel sites within the Mourne Mountains area see the following sites: Key Site 440 - Mourne Plain Complex - Overview Key Site 448 - Bloody Bridge River Valley Complex, Mourne Mountains - Overview Key Site 449 - Northeast Mournes Complex - Overview Key Site 450 - Western Mournes Complex - Overview Key Site 451 - Annalong Valley For general information and references on the sand and gravel landscapes of N. Ireland, and directions to sites other than those within the Mourne Mountains area, see the following site: Key Site 439 - Introduction to the Sand and Gravel Landscapes of N. Ireland | |
| Keywords | |
|---|---|
| Geomorph: | outwash |
| Record type: | ESCR report | ||
| Entered by: | E M Porter | ||
| Last updated: | 7 Jan 2005 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Attical Complex - Attical Valley Outwash, County Down, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=462. Accessed on 2026-11-04. |
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