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Earth Science Conservation Review
| Kilrea - site of local interest | Londonderry |
| Site number: | 734 | ||
| Locality Type: | Inland exposure, Pit | Status: | local interest |
| Grid Reference: | C920170,C948037 Corners of site | ||
| Google maps: | 54.99243,-6.56261 | ||
| County: | Londonderry | Council area: | Causeway Coast & Glens Borough Council |
| Period: | Quaternary | ||
| Site Description | |
|---|---|
| Highlights: | |
The complex of deposits of the central Bann Valley demonstrates a close topographic association between subaqueous outwash, deltaic and esker depositional environments. Successive ice-marginal fronts ended in ponded water as the ice mass contracted southwards. | |
| Description: | |
This deglacial complex is located in a structural low in the Antrim basalts, 15km to the north of Lough Neagh, and bordered 15km to the west by the Sperrin Mountains and 5km to the east by the Long Mountain. The complex is around 16km long and up to 2km wide consisting of ridge segments characterised in places by steep ice-contact slopes interspersed with topographic flats and areas of hummocky topography. The margin of the deposit feathers onto and overlies the streamlined rock ridges and drumlins of the Bann Valley. The complex is subdivided into four principal morphological units from north to south. Centred on Vow [D918 177] is a 2km wide zone of ENE-WSW trending flat-topped ridges of relatively low relief and NNE-SSW trending beaded ridges. West of the Bann from Movanagher to Kilrea is a 3.5km long, 0.5km wide zone of sharp-crested and flat-topped ridges. Immediately south of Kilrea is an area of hummocky ground with interspersed lakes within enclosed depressions in stratified drift. Finally, an approximately 7km long zone of discontinuous steep-sided ridges and mounds of medium relief (20-40m) orientated generally NNE-SSW occurs between Drumimerick Hill [D932 103] and Inishrush [D948 037]. Exposures of the sediments are rare, though a pit at Vow contains lithofacies associations of boulder clay, sand and rhythmites. Rhythmites are also exposed in a pit at Artiloman [D909 168] while at Moneygran [D944 108] there is an exposure of slumped and convoluted horizontally bedded cobble gravels and pebbly sands overlain by cross-bedded sands fining upwards into laminated silts. | |
| Importance: | |
The Kilrea complex is of scientific importance as it provides a range of sedimentary and geomorphological evidence for constructing an hypothesis to explain the nature of deglaciation in the mid-Bann Valley. | |
| Interpretation: | |
The deposits at Vow are interpreted as a subaqueous outwash complex formed from a subglacial efflux into ponded water. Rapid ice retreat did not allow the aggradation of sediment to the elevation of the water body surface and thus the full development of deltaic morphology. To the south the elevated topographic flats of Tully Hill and the site of Kilrea probably record glaciolacustrine delta deposition from a subglacial conduit feeding into a proglacial lake. The deltas record temporary halts in the retreat of the glacier front to allow aggradation of sediments to the level of the water body surface. The esker deposits to the south and adjoining the southern (ice-contact) slopes of the flat-topped ridges are interpreted as representing the course of efflux feeder channels. The enclosed depressions immediately south of the delta resulted from the melt-out of ice blocks buried under aggrading sediments. The steep-sided, sharp crested ridges south of Kilrea probably record ice-contact deposition in high-energy, subglacial tunnels and are partially overlain by the younger sediments exposed at Moneygran. They are interpreted as deformed, subaqueous outwash. The sequence of deposits indicates the presence of a ponded proglacial waterbody during the retreat of the ice margin southwards from Vow to Moneygran. | |
| Notes: | |
See also ESCR Key Site 467 - Kilrea [Sand and Gravel Landscapes Block]. | |
| Keywords | |
|---|---|
| Rocks: | Gravel, Sand |
| Relations: | Deltaic sediments, Glaciolacustrine deposit, Ice retreat, Subaqueous outwash |
| Geomorph: | delta, esker, proglacial lake, subaqueous fan, rhythmite |
| Paleoenv: | deglacial |
| Measurements | |||||
|---|---|---|---|---|---|
| Length: | 16km | Width: | 2km | Height: | |
| Depth: | Area: | ||||
| Access | |
|---|---|
| Approach: | This site is a deglacial complex stretching south from Vow [D918 277] to Inishrush [D946 034]. |
| Uses | |
| Educ. Level: | The complex is of some educational value to researchers and students of glaciology. |
| Record type: | SLNCI Report | ||
| Entered by: | E M Porter | ||
| Last updated: | 09/10/03 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Kilrea - site of local interest, County Londonderry, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=734. Accessed on 2026-11-06. |
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