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Earth Science Conservation Review
| Attical Complex - Attical Valley Moraines | Down |
| Site number: | 461 | ||
| ESCC: | IS | ||
| Locality Type: | Inland exposure | Status: | TBC |
| Grid Reference: | J293258,J265270,J276197,J260175 Corners of site, Not Entered | ||
| Google maps: | 54.16539,-6.02031 | ||
| County: | Down | Council area: | Newry, Mourne & Down District Council |
| Period: | Quaternary | ||
| Stages: | Late Midlandian | ||
| Site Description | |
|---|---|
| Description: | |
The deposits will be described from south to north along the White Water valley, as far as the junction of the valley with its tributaries. These valleys will then be described from east to west. A. WHITE WATER RIVER VALLEY The southernmost ridge in the White Water river valley is a gently rounded ridge, ca. 500m wide by 15m high, located near the southern entrance of the valley between Knockchree Mountain and Rocky Mountain. Six sub-parallel cross-valley ridges which occur northwards along the valley towards the footslopes of Brown Hill (J270191) are broad (up to 250m) and round-crested. The ridges are banked against the flanks of Knockchree Mountain and Rocky Mountain, and occur at progressively higher elevations northwards. The northward rising series overlaps and cross-cuts another series of ridges on the slopes of Rocky Mountain which fall in elevation northwards. A broad, well-defined ridge which forms an arc to the east of Attical also cuts across an earlier moraine on the north flank of Aughrim Hill (J284189). The ridge located at the mouth of the valley occurs ~700m north of a ridge which marks the limit of a Late Midlandian readvance from Carlingford Lough. B. YELLOW WATER VALLEY MORAINES Continuous but rather subdued cross-valley ridges and benches in the Yellow Water valley are restricted to near its junction with the White Water River valley where the low (<3m high in the valley bottom), round crested ridges have been truncated by a ridge which extends southward from Slieve Muck. A small excavation in a ridge (J284226) has exposed horizontally bedded stratified sand and gravel. Bed boundaries are rippled. Ridges which tend along the valley sides are frequently capped by spreads of glacially rounded boulders. The valley bottom contains little topographic relief apart from occasional dispersed rounded boulders for a distance of ~1km to the south of Lough Shannagh. The Slieve Muck corrie is a ~400m wide by ~200m long shallow bowl and contains discontinuous belts of arcuate hummocks. A small poorly revealed exposure at J291252 in a stream bank within this belt consists of horizontal beds of stratified coarse sand and granules. Four to five discontinuous round-crested hummocky ridges also occur to the south and east of Lough Shannagh. Ridges grade into benches to the west of the lough against the lower slopes of Carn mountain, and to the north of the lough against the col between Carn Mountain and Doan. At one location (J292253) the ridges cross-cut a ridge subparallel in orientation to ridge crests on deposits at the Slieve Muck corrie. C. WHITE WATER VALLEY MORAINES Large, smooth-crested cross-valley moraines occur in a suite northwards from Tullyframe, and have an arcuate form (concave northwards) where the valley broadens in the Attical area. Underfit streams now occupy deeply incised meltwater channels which dissect the ridges. To the east of Crocknafeola the north-south draining valleys of the White Water and Yellow Water are separated by a large (~20m high) smooth-crested ridge projecting from the southern flank of Slieve Muck. Twenty-one low, hummocky, ridges and benches occur in the upper White Water valley between Crocknafeola and the southern entrance to Deers Meadow (a distance of ~3.5km) Small pits excavated in these features expose diamict and dirty gravel, although a more substantial, overgrown, excavation (J271225) contains sand and gravel. The ridges in Deers Meadow are low (<5m high), and smooth crested, and forming discontinuous arcs centred on the pass. A horizontal, poorly developed notch extends for ~1km along the western slope of the basin, at ~360m a.s.l. Stream channels in the floor of the basin expose horizontally stratified sand and granule to pebble gravel. D. ISLAND ROAD EXPOSURE A pit at Island Road (J273212) has been excavated in the northern side of a ridge at the southern end of the valley which separates Crocknafeola from the southern spur of Slievemageogh. Two facies are present. Facies description F1 consists of interbedded silty mud to fine sand and stratified gravel. Poorly exposed, interbedded laminated silty mud to fine sand (<1m thick) has an erosional, undulating contact with overlying interbedded poorly sorted gravel (<0.9m thick). Mud beds (<30cm) are marked by pebble and cobble lines. Channels in the gravel (<3m wide) are frequent, and are often marked by basal cobble lines. Channel fill consists of sandy diamict or crudely stratified pebble to cobble gravel. Occasional mainly pebble lenses are better sorted, with normal grading. Discontinuous granule to small pebble beds (<5cm thick) grade laterally from matrix support to clast support to openwork. Isolated boulders (<40cm) deform underlying beds. A granite boulder (ca. 1.8m) is grooved by cross-cutting striae (<6mm deep). F2 consists of (<3m thick) crudely stratified sandy to gravely diamict. The junction between the two facies is gradual. Beds (<0.5m thick) are undulating, show lateral and vertical textural variability, and are often marked by cobble lines or thin layers of gravel (<30cm). E. PIGEON ROCK RIVER VALLEY MORAINES The confluence of the White Water and Pigeon Rock River valleys (J273205) is marked by a broad, smooth-crested ridge which projects southward from Slievemageogh. A ridge in the White Water valley which intersects this ridge at a high angle cuts across two other ridges at this location. Cross-valley ridges in the Pigeon Rock River valley are markedly hummocky at a variety of scales. Deposits at the entrance to the valley are slightly convex spreads rather than ridges, with low (<2m) discontinuous hummocks and larger hummocks (>4m high) upstream (J258220). An irregular topographic flat ringed by a well-preserved notch enclosing an area of ~500m2 occurs at (J258222). More continuous low hummocky moraines cross the valley up to the col between Pigeon Rock Mountain and Slievemoughanmore (J256243). Ridges and ridge segments oriented sub-parallel to the Shanlieve and Eagle Mountain corries cut across cross-valley ridges in the Pigeon Rock valley. The Shanlieve corrie floor has an area of ~ 30ha, and ridges occurring at the entrance are sharp to round crested, up to 50m wide. Eagle mountain corrie ridges are less continuous and less distinct. | |
| Interpretation: | |
A. WHITE WATER VALLEY Situated an the southern fringe of the Mourne Mountains the White Water valley was subject to ice invasion from two directions during the last glacial period. Evidence for the valley lobes is in the from of ice-contact morphology and the patterns formed by moraine ridges in the valleys. The different retreat directions of the valley lobes are indicated by the altitudinal pattern of the ridges. Assuming that the ice mass surface thinned towards the snout, the series of subparallel moraine ridges therefore which rise to the north along the valley indicate deposition at ice margins receding into higher altitudes. These deposits cut across moraines of the main Late Midlandian retreat phase on the slopes of Rocky Mountain, which in contrast rise towards the south. At the extreme southern end of the valley, the break of slope on the southern side of the broad ridge may be an ice contact slope, associated with ice pressure to the south and linked to the main phase of late-Midlandian ice frontal retreat southwards from the foothills of the Mourne massif and back along Carlingford lough. In the valleys, as the ice surface lowered during the glacier's retreat northward it was split by the bedrock mass of Crocknafeola (291m). The ridge at the junction of the White Water and Yellow River valley record the eastern extent of the White Water glacier before its diversion to the southwest by a bedrock high (J284205). Sediments exposed in the Island Road pit record the processes of deposition and style of retreat of the glacier as it was funnelled between these topographic highs. The closely packed, low ridges and benches in the upper valley are inferred to be a result of the frequent re-equilibration of the ice front. From the attitude of the ridge segments and regional interpretation, it is inferred that the ice-front of the valley lobe retreated northwards out of Deers Meadow via the pass between Spelga Mountain and Slievenamiskan. B. YELLOW WATER RIVER VALLEY The cross valley moraines at the entrance of the Yellow Water valley relate to the phase of main Late Midlandian retreat. Subdued boulder studded relief to the south of Lough Shannagh records stagnation zone retreat as the lobe's ice surface elevation fell below the altitude of the col between Slieve Meelbeg and Slieve Meelmore, cutting the valley off from its ice supply. During the readvance phase, ice sources were restricted to the Slieve Muck corrie and Lough Shannagh icefield, resulting in a limited expansion of local ice onto the area of subdued relief. The most distal belt of hummocky moraine records the extension of a glacier tongue for ca. 1km along the western side of the valley from Slieve Muck. The morainic deposits at Lough Shannagh record recession of a localised ice body which developed in the lough basin. The pit at Island road, at the junction of the White Water and Yellow River valleys contains a sediment sequence which indicates deposition in an ice marginal environment. Diamict and gravel facies which are characterised by poor sorting, layers of tractional gravel, matrix support and channelization suggest that subaerial sediment flow was the main depositional process (Lawson, 1982). Laminated mud which incorporates sandy underflows probably records ponding on an undulating flow surface. Better sorted, fining up gravel lenses are the result of waning flow pulses. Variably supported beds record changing flow competence, resulting in sediment bypass in openwork gravel. Isolated boulders probably record gravity fall from the ice front which deformed unconsolidated sediments. It is inferred that readvance ice occupying the Yellow Water valley did not extend to join with coeval ice in the White Water River and Pigeon Rock River valley. Ice in these two valleys had its ultimate source in the Lough Neagh Basin. Intersecting moraines north of Attical record changes in the relative ice pressure of the glaciers emanating from the valleys, and the overlapping patterns indicate that there was a considerable degree of ice front oscillation in the valleys. Hummocks in the valley record deposition onto partially buried ice and stagnation zone conditions in the valley with larger accumulations probably recording relatively longer standstills of the ice front. Shanlieve corrie moraines superimposed on Pigeon Rock River cross valley moraines indicate that the final moraine forming phase in the valley was a readvance of local ice. An irregular topographic flat near Lough Shannagh (J258222) is inferred to represent the bed of a small inter-moraine lake. Inter-moraine ponding is inferred to have been common during retreat of ice through the valleys. Rippled deposits (J284226) within the main retreat phase moraines record subaqueous deposition. Stratified coarse sand and granules (J291252) record inter-moraine ponding during retreat of corrie ice. | |
| Notes: | |
For site specific information on other sites within the Attical Complex see the following site: Key Site 462 - Attical Complex - Attical Valley Outwash 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: | moraine ridge, readvance moraine |
| 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 Moraines, County Down, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=461. Accessed on 2026-11-04. |
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