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Earth Science Conservation Review
| Lough Fea - site of local interest | Londonderry, Tyrone |
| Site number: | 737 | ||
| Locality Type: | Inland exposure | Status: | local interest |
| Grid Reference: | H799879,H748855 Corners of site | ||
| Google maps: | 54.73318,-6.75965 | ||
| County: | Londonderry, Tyrone | Council area: | Mid Ulster District Council |
| Period: | Quaternary | ||
| Site Description | |
|---|---|
| Highlights: | |
The deposits of the Lough Fea platform record the phased decay of an ice lobe from this upland structural depression and the strong influence of bedrock topography on the patterns of local ice marginal retreat. | |
| Description: | |
The deposits of the Lough Fea platform record the phased decay of an ice lobe from this upland structural depression and the strong influence of bedrock topography on the patterns of local ice marginal retreat. Ice marginal ridges and kame terraces mark the successive positions of a downwasting and backwasting ice mass. The ice, subject to bedrock control and ice pressure, split during the process of retreat to form two discrete ice lobes. Sediments of the western part of the glaciofluvial complex were partially supplied by the north-northeast to south-southwest trending Davagh esker complex, which conducted subglacial meltwater and debris northwards from the Ballinderry valley lowlands, against the local topographic gradient. The complex comprises 17 subunits covering the Lough Fea platform and the flanks of the upper Moyola valley as follows: Crockandun Terrace, Corick Terrace, Carnabane Ridge and Terrace, Brackagh Ridge and Plain, Slaught Ridge, Stone Hill Ridge, Mill Lough Ridge, Teal Lough Plain, Davagh Ridge Complex, Black Lough Ridge, Ballybriest Ridge, Lough Fea Depressions, Grouse Lodge Ridge, Lissan Ridges and the Moyola Valley, and Disert Ridges. The landform and sediment assemblages are inferred to represent ice-marginal deposition during the phased deglaciation of the Lough Fea platform. It is inferred, from both the local granitic and basic igneous erratic content of the deposits and the evidence of ice movement patterns from adjacent areas, that the area was occupied by ice of southerly origin during the last glacial cycle. During the deglacial cycle, ice on the Lough Fea platform separated from Bann valley ice occupying the Moyola valley lowlands. It then progressively downwasted and backwasted from two lobes, one located in the Broughderg valley to the southwest and the other in the Lissan valley to the southeast. The pattern of ice retreat was thus controlled by the location of local bedrock highs and the direction of ice pressure. The ice finally retreated into the lowland areas south and east of the Sperrin Mountains accompanied by the production of ice marginal and proglacial lakes due to the impounding of meltwater against the rising ground of the mountain range. | |
| Importance: | |
The complex is of scientific significance and demonstrates: 1. A wide variety of deglacial depositional environments (outwash plain, moraine ridges, fan deltas, subaqueous moraines) and sediment supply mechanisms (e.g. eskers, meltwater channels, sub-aqueous effluxes); 2. The coincidence and juxtaposition of glaciogenic landscape elements (e.g. esker orientation and moraine ridge position; moraine ridges and outwash plains), showing the spatial and temporal evolution of the complete deglacial landform development sequence from sediment supply routes through to subaerial reworking and erosion of sediments; 3. The influence of bedrock topography upon the spatial pattern of deglaciation, ice mass splitting and lobe formation, and the location of ice marginal deposits; 4. The formation of kettle holes, namely the depressions occupied by Lough Fea, Teal Lough, Mill Lough, Black Lough, Cow Lough and Lough Patrick; 5. The southerly origin of ice which occupied this region of the Sperrin uplands during the last glacial cycle. | |
| Notes: | |
Much of the area is remote and of high amenity value for countryside activities. A walking route exists around part of Lough Fea. See also ESCR Key Site 477 - Lough Fea [Sand and Gravel Landscapes Block]. | |
| Keywords | |
|---|---|
| Relations: | Glacio-fluvial sediment, Ice retreat, Subaqueous outwash |
| Geomorph: | deltas, esker, kame terrace, kettle-hole, moraine ridge, subaqueous fan |
| Paleoenv: | deglacial |
| Access | |
|---|---|
| Approach: | This site is located between Fir and Glenarudda Mountains. |
| Uses | |
| Educ. Level: | The site is of significant educational value for researchers of glaciology. |
| Record type: | SLNCI Report | ||
| Entered by: | E M Porter | ||
| Last updated: | 09/10/03 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Lough Fea - site of local interest, County Londonderry, Tyrone, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=737. Accessed on 2026-11-06. |
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