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Earth Science Conservation Review
| Bloody Bridge River Valley Ridges | Down |
| Site number: | 453 | ||
| ESCC: | IS | ||
| Locality Type: | Inland exposure | Status: | TBC |
| Grid Reference: | J383270,J363263 Approximate, Not Entered | ||
| Google maps: | 54.17382,-5.88206 | ||
| County: | Down | Council area: | Newry, Mourne & Down District Council |
| Period: | Quaternary | ||
| Stages: | Late Glacial | ||
| Site Description | |
|---|---|
| Description: | |
The Bloody Bridge valley contains two distinct sets of cross-cutting ridges. One set terminate at the Chimney Mountain corrie, the other, larger set continuing along the entire length of the valley to the col. 1. CROSS-VALLEY RIDGES The Chimney Corrie ridges cut out larger cross-valley ridges which form a set which reaches into the higher altitudes of the valley. These ridges are wider, extend further up the valley sides, and are frequently higher and more irregular in outline. Ridges are up to 70m wide and up to 4m high. The crests and slopes are frequently lined with massive boulders, particularly in the middle section of the valley with two or three boulders occasionally stacked together. Sediment exposures within these ridges are rare, and are confined to occasional small patches of diamict on some of the steeper slopes. Clasts are highly variable in composition, angular to well-rounded, up to boulder size, and frequently supported in a clay-rich matrix. Greywacke clasts in the lower exposures are often striated. 2. CHIMNEY ROCK MOUNTAIN CORRIE RIDGES Hummocky, incised arcuate ridges occur from an altitude of 100m in the lower reaches of the Bloody Bridge valley to a corrie located at 500m on the southeast slopes of Chimney Rock mountain. The three most distal ridges cross the gorge floor south of the Bloody Bridge/Glen Fofanny River confluence (J383270). On the north side of the river at the Bloody Bridge/Glen Fofanny River triangle, ridges form a series of concentric arcs, with the largest of these ridges up to 10m high. A low relief ridge occurs parallel to the gorge sides (J380269). Further west, small-scale arcuate ridges and benches occur on either side of the river gorge. The arcs of well-marked, round-topped ridges at the corrie entrance have a chord measurement of 500m. | |
| Interpretation: | |
1. CROSS-VALLEY RIDGES The cross-valley ridges cut out moraines of the main retreat phase which are thus interpreted to record retreat of an valley based glacier westwards into the mountains. The main retreat phase ridges are larger than the corrie based-readvance ridges, probably a result of more extensive, thicker ice with a greater volume of sediment supply. The ridge crests and distal slopes carry two or three boulders are occasionally stacked together, possibly the result of rolling down steep ice-distal slopes. 2. CHIMNEY ROCK MOUNTAIN CORRIE RIDGES The arcuate ridges in the Bloody Bridge valley record retreat of ice at a tangent to the line of the valley, into the corrie on the northern flank of Chimney Rock Mountain (J363263). Standstills are defined by minor arcuate ridges and benches on either side of the river gorge. Many of the ridges are well preserved, and indicate the pattern and style of ice retreat into the Chimney Rock Mountain corrie. These readvance moraines are largely confined to a corridor along the valley, except where corrie ice spread into a minor lobe (J378270) where it breached a well-marked moraine of the main Late Midlandian retreat phase. The most distal readvance moraines (J383270) cross the floor of the gorge which had been incised by meltwater from this previous phase of ice retreat into the mountains. These moraines indicate that the gorge existed prior to the readvance, and was probably a major route for meltwater during the main retreat phase. During retreat of corrie ice the deposits were dissected and the gorge re-excavated by meltwater from the retreating glacier, supplying sediment to form the glaciofluvial fan located beyond the line of the most ice-distal ridges. The ice readvance ridges also post-date and cut across moraines on the lower eastern slopes of Crossone and Chimney Rock Mountain which record downwasting of the Late Midlandian ice margin along the coastal margin of the Mournes. | |
| Notes: | |
For site specific information on other sand and gravel sites within the Bloody Bridge River Valley Complex see the following sites: Key Site 452 - Bloody Bridge River Outwash Key Site 454 - Bloody Bridge River Fan For overview information and references on the Bloody Bridge River Valley Complex see the following site: Key Site 448 - Bloody Bridge River Valley Complex - 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 447 - Attical Complex, Mourne Mountains - Overview Key Site 449 - Northeast Mournes Complex - Overview Key Site 450 - Western Mournes - Overview Key Site 451 - Annalong Valley For general information and references on the sand and gravel landscapes of N. Ireland, and for directions to sand and gravel 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: | corrie, cross-valley moraine, valley glacier |
| Record type: | ESCR report | ||
| Entered by: | E M Porter | ||
| Last updated: | 8 Jan 2005 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Bloody Bridge River Valley Ridges, County Down, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=453. Accessed on 2026-11-05. |
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