ESCR - Faughan and Dungiven Basins

Earth Science Conservation Review

Summary Full report
Faughan and Dungiven Basins - Overview	Londonderry

Site number:	470
ESCC:	IS
Locality Type:	Inland exposure, Pit	Status:	TBC
Grid Reference:	C690095 Centroid
Google maps:	54.92879,-6.92367
County:	Londonderry	Council area:	Causeway Coast & Glens Borough Council
Period:	Quaternary

Site Description
Highlights:
Deltaic deposits are preserved at seven principal locations and are grouped within three main altitudinal levels, representing the control of former ice-dammed lake levels on their formation. They are of special scientific interest, as their widespread extent and relationship to proglacial water levels implies that substantial, deep lakes were impounded along the Faughan and upper Roe valleys as Irish ice masses retreated southwards and Scottish ice advanced southwestwards into the lower Roe valley. The upper Roe (Dungiven) and middle to upper Faughan valley basins have been used for mineral aggregate production in the northwest of the province for approximately twenty years. Quarry excavations have exploited the area's abundance of high quality sand and gravel deposits and provided numerous cross-sections within sedimentary sequences.
Description:
The upper Roe and Faughan rivers drain the northern flanks of the Sperrin Mountains. The valleys are developed mainly in Precambrian schists flanked by Carboniferous and Permo-Triassic sediments in the east, below the basaltic escarpment. Both systems drain generally northward along entrenched valleys and are linked by a deep west to east trending structural low, the Foreglen depression. The glaciofluvial deposits occur on at least four topographic settings: 1. Flat-topped high-level (243m O.D.) deltas are perched on north facing mountain slopes having been fed by meltwaters flowing north between cols in the Sperrin range (e.g. Murnies, Templemoyle.) 2. The main group of flat-topped deltas occurs within the valleys and along the valley sides. Generally the margins of the features have been eroded and oversteepened by glaciofluvial erosion. Present rivers are mainly misfit and occupying the former meltwater features eroded into the delta flanks. The present form and distribution of the delta fragments suggest that they once filled the valleys, but are now dissected. This situation is best seen along the middle Faughan valley around Gosheden and in the Owenrigh valley, where deltaic fragments and outwash terraces are perched on both sides of the present rivers. 3. At two sites in the upper Faughan basin, Dreen and Tamnagh, ridges form cross-valley features (moraines) associated with short halts in ice-front retreat. 4. Extensive erosion and removal of debris, post-dating delta formation, has occurred along the valley floor north and west of Dungiven and along part of the Foreglen depression. Flat spreads and terraces of resedimented material dominate the topography along the lower valley of the Owenrigh and Owenbeg Rivers. For site specific information see the following sites: Key Site 499 - Faughan and Dungiven Basins - The Murnies Key Site 500 - Faughan and Dungiven Basins - Derrynaflaw Key Site 501 - Faughan and Dungiven Basins - Banagher Key Site 502 - Faughan and Dungiven Basins - Templemoyle Key Site 503 - Faughan and Dungiven Basins - Tamnagh Key Site 504 - Faughan and Dungiven Basins - Cumber Key Site 505 - Faughan and Dungiven Basins - Gosheden Key Site 506 - Faughan and Dungiven Basins - Fawney Key Site 507 - Faughan and Dungiven Basins - Enagh
Importance:
The delta fragments are important for the following reasons: A) The position of the deltas indicates that an extensive body of water was impounded between advancing Scottish ice and decaying Irish ice. The former glacial lake is therefore an important in regional glacial chronology in the absence of biostratigraphic markers. B) The deltas are important examples of prograded foreset and topset structures. C) The variable height of the deltas record lake level changes which are a response to the strength and permanence of Scottish ice. The latter is probably due to a major surge of ice southwest from Scotland across the Malin sea and may have important implications for the interpretation of offshore seismic records.
Interpretation:
The presence, structure and distribution of the landforms indicates the formation of a large (approximately 200km2 at max. extent) proglacial lake during the late glacial period north of the Sperrin mountains. The altering elevation of deltaic topset sedimentation represents a rising lake level and periodic stagnation of the ice front as the ice mass actively retreated generally southwards. The efflux of glacial drainage into the lake took a variety of forms at different locations resulting in sedimentologically and morphologically different deposits. Many more of these landforms were probably removed post-glacially during and after drainage of the lake. Their sub-areal exposure and erosion by meltwaters resulted in the reworking of the deposits into flat-lying outwash gravels. Alternatively the retreat of the ice was insufficiently slow to allow the aggradation of other deposits. The available sedimentary and morphological evidence suggests that the lake resulted from dams of both Scottish and Irish ice provenance. At the time of formation, the Scottish ice front was located near Limavady, Co. Londonderry (267500 423000) to the northeast with Foyle ice damming the Faughan depression at Drumahoe (246700 414700).
Notes:
For general information and references on the sand and gravel landscapes of N. Ireland, and for directions to other regional sand and gravel sites, see the following site: Key Site 439 - Introduction to the Sand and Gravel Landscapes of N. Ireland

Keywords
Rocks:	Gravel, Sand
Relations:	Deglacial sediments
Geomorph:	deltaic foresets, deltas, ice-dammed lake, proglacial lake

Measurements
Length:		Width:		Height:
Depth:		Area:	150km2

Access
Management:
The genetic connectivity of the widely distributed deposits links their conservation worthiness. As evidence for a varying lake level each deltaic deposit is scientifically important in modelling the chronology of ice mass activity in the area. However several landforms or associations may demonstrate the same glaciological point and therefore their conservation worthiness changes. Already many of the delta bodies have been subject to intensive disruption and removal by commercial quarrying operations. At these locations, spoil heaps and pit scars are visually obtrusive in the rural landscape. In addition commercial operations on these scales bring volumes and types of vehicular traffic unsuited to and destructive to the typical rural roadways found here. Of note are the quarries at Cumber, Templemoyle and Banagher (McCabe, 1994). At the Murnies, Tullintrain, Derrynaflaw and Templemoyle, abandoned pits have undergone little restoration and remain visible from considerable distances throughout the area.

Access

Management:

The genetic connectivity of the widely distributed deposits links their conservation worthiness. As evidence for a varying lake level each deltaic deposit is scientifically important in modelling the chronology of ice mass activity in the area. However several landforms or associations may demonstrate the same glaciological point and therefore their conservation worthiness changes. Already many of the delta bodies have been subject to intensive disruption and removal by commercial quarrying operations. At these locations, spoil heaps and pit scars are visually obtrusive in the rural landscape. In addition commercial operations on these scales bring volumes and types of vehicular traffic unsuited to and destructive to the typical rural roadways found here. Of note are the quarries at Cumber, Templemoyle and Banagher (McCabe, 1994). At the Murnies, Tullintrain, Derrynaflaw and Templemoyle, abandoned pits have undergone little restoration and remain visible from considerable distances throughout the area.

References (2)
Colhoun, E.A., 1971. The glacial stratigraphy of the Sperrin Mountains and its relation to the glacial stratigraphy of north-west Ireland. Proceedings of the Royal Irish Academy, vol. 71B, pp.37-52.
McCabe, A.M., 1994. Sand and Gravel landscapes in Northern Ireland - a scientific basis for conservation Earth Heritage, vol. 2, pp.18-22.

Record type:	ESCR report
Entered by:	E M Porter

Enlander, I., Dempster, M. & Doughty, P., 2026. Faughan and Dungiven Basins - Overview, County Londonderry, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=470. Accessed on 2026-11-06.