| Previous Site | Next Site |
Earth Science Conservation Review
| Ballinderry - site of local interest | Tyrone |
| Site number: | 701 | ||
| Locality Type: | Inland exposure | Status: | local interest |
| Grid Reference: | H683812,H629782 Corners of site | ||
| Google maps: | 54.67472,-6.94125 | ||
| County: | Tyrone | Council area: | Fermanagh & Omagh District Council |
| Period: | Quaternary | ||
| Site Description | |
|---|---|
| Highlights: | |
The Ballinderry deglacial complex consists of large cross-valley morainic ridges, flat-topped glaciolacustrine deltas and outwash terraces. Associations between subglacial feeder channels and proglacial sedimentation are clearly demonstrated. | |
| Description: | |
The Ballinderry deglacial complex consists of large cross-valley morainic ridges, flat-topped glaciolacustrine deltas and outwash terraces. Associations between subglacial feeder channels and proglacial sedimentation are clearly demonstrated. Periods of ice-margin retreat-rate reduction, high sediment fluxes and the presence of proglacial ponded waterbodies resulted in the formation of extensive, flat-topped deltaic sediment bodies. Relatively minor advances of ice-margins during general retreat are recorded in tectonically-deformed cross-valley ridges. Overall, the morphology and sedimentology records an eastward and southward phased backwastage of ice from the Lough Fea platform towards the Lough Neagh lowlands. At one site (Lough Doo), the combination of an esker system, ponded waterbody and flat-topped delta form an aesthetically excellent topographic association. This association provides a clear picture of the relationships between subglacial channels (eskers) and the feeding of an ice-marginal delta. | |
| Importance: | |
The complex is of scientific significance due to: 1. the excellent examples of subglacial esker channels feeding a proglacial delta at Cam Lough where a distinct ice-contact slope also clearly defines the ice-marginal position; 2. the occurrence and exposure of cross-valley ridges, formed as a result of glaciotectonic stresses applied to proglacially deposited sediments; 3. the relatively concentrated evidence for late-glacial decay patterns in the area, i.e. the complex clearly demonstrates a west to east active retreat of the ice towards the Bann valley lowlands from the eastern flanks of the Sperrin Mountains; 4. excellent examples of flat-topped Gilbert-type deltas provide firm evidence that late-glacial lake levels of 235m O.D., 188m O.D., 180m O.D. and 140m O.D. occurred in the deglaciated margins of the Sperrin Mountains; 5. the complex demonstrates the influence of bedrock topography on the advance and decay patterns during a deglacial cycle, with bedrock topography only exerting a significant controlling influence during the deglacial period; 6. the complex contains an excellent exposure of classic Gilbert-type delta foresets and topsets at Evishanoran and an excellent example of glaciotectonic shears at Muntober. | |
| Interpretation: | |
The topographical, morphological and sedimentological evidence suggests the following pattern of ice mass advance and decay in the Ballinderry River area: ice advanced northwards across the highland area of Cregganconroe and around both its western and eastern flanks from a more southerly origin, as far as the Lough Fea platform. The ice pressure must have been restricted by the upstanding bedrock, thus concentrating erosive power on the granite outlier. The flow pattern produced southeast/northwest drumlin orientations in the broad lowland zone south of Drum Manor, to the east of the highlands, and accounts for the high proportions of granite clasts found in the sediments. During this phase, sediment was channelled under high hydrostatic pressures along the Davagh esker northwards from the Cregganconroe highlands across the Ballinderry valley and uphill towards the Lough Fea complex. During deglaciation, ice-margin retreat proceeded southwards into the Ballinderry valley and Creggan outwash plain through the cols between Mullaghturk [H669 892] / Evishbrack [H701 828], Evishbrack / Beltonanean Mountain [H701 828] and Oughtmore [H724 837] / Fir Mountain [H747 854]. Further downwastage resulted in the formation of four lobes in the upper Ballinderry river valley region. One lobe backwasted to the west, forming the Creggan outwash plain. One backwasted eastward along the Ballinderry river valley, separated by the rising bedrock slopes of Slievemore [H688 786] and Evishanoran from the third lobe, which backwasted towards the highlands of Cregganconroe. | |
| Notes: | |
At one site (Lough Doo), the combination of an esker system, ponded waterbody and flat-topped delta forms an aesthetically excellent topographic association. See also ESCR Key Site 480 - Ballinderry [Sand and Gravel Landscapes Block]. | |
| Keywords | |
|---|---|
| Relations: | Glacial deposit, Glaciolacustrine deposit, Glaciotectonic |
| Geomorph: | flat-topped delta, Gilbert-type delta, moraine ridge, outwash terrace |
| Paleoenv: | glacial |
| Access | |
|---|---|
| Approach: | Located in County Tyrone between An Cregán and Dunnamore. |
| Uses | |
| Educ. Level: | The site is of significant education 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. Ballinderry - site of local interest, County Tyrone, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=701. Accessed on 2026-11-04. |
| Previous Site | Next Site |