ESCR - Ballinderry - deglacial landscape

Earth Science Conservation Review

Summary Full report
Ballinderry - deglacial landscape	Tyrone

Site number:	480
ESCC:	IS
Locality Type:	Inland exposure	Status:	TBC
Grid Reference:	H683812,H629782 Centroid, Not Entered
Google maps:	54.67472,-6.94125
County:	Tyrone	Council area:	Fermanagh & Omagh District Council
Period:	Quaternary

Site Description
Highlights:
The complex consists of large cross-valley morainic ridges, flat-topped glaciolacustrine deltas and outwash terraces. Associations between subglacial feeder channels and proglacial sedimentation is 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, Co. Antrim. 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.
Description:
The deposits of the Ballinderry complex are grouped and described based on the evolution of successive ice-marginal positions developed during the phased deglaciation of the area. The location of the ice-margins and thus pattern of ice backwastage during the deglacial period is based on deposit location, sedimentology, morphology and the bedrock topography. PHASE 1: DAVAGH ESKER (LOWER PORTION) A topographically distinct, 0.7km long, 20m wide and 8m high steep-sided ridge transverses the western part of the Ballinderry river valley near Teebane (267700 380500) at 150m O.D. One small-scale exposure (4m long by 15m deep) in the flank of the ridge at (268300 381200) consists of large scale (<20m deep) amalgamated beds of clast-supported, polymodal boulder gravel (60%) and massive cobble and pebble gravel (40%). Poorly-defined a-axis imbrication of the clasts (50-60cm) and cross-bed dips (20°) indicate a general palaeoflow to the north. The ridge continues in a sinuous path northwards for 5km towards the Lough Fea platform to a maximum of 210m O.D. (see also Key Site 477 - Lough Fea Platform). PHASE 2: CREGGAN RIDGES, KILLUCAN DELTA AND LOUGH DOO ESKERS A. Creggan Ridges At Creggan (262900 378200), two 60m long by 15m high cross-valley ridges, oriented northwest/southeast and north/south occur approximately 0.25km apart. The ridges have steep eastern flanks and gently sloping western flanks. 1.5km to the west, an extensive topographic flat covered by peat bog is situated at the eastern end of the Owenreagh valley. One almost completely grassed exposure in the plain shows generally poorly-sorted sand and pebble gravel contained in channels with a palaeoflow towards 120°N. Immediately south of the plain, on the eastern margin of Loughmacrory Hill (259100 377300), a 0.2km long by 10m wide beaded, sharp-crested ridge rises approximately 10m above the surrounding low-relief topography. The ridge is oriented north/south and terminates southwards at the northern margin of a small (<0.24km2) flat-topped, peat-covered ridge. The flat-top occurs at an elevation of 190-200m O.D. B. Killucan Delta Immediately southeast of the Davagh esker ridge, at Killucan (267900 379600), a relatively large (2.5km2) flat-topped deposit occurs to a maximum elevation of 180m O.D. The deposit is bordered by the course of the Ballinderry river on its northern flank. Killucan Delta: Exposure 1 An exposure (267400 379700), visible from the A505 Cookstown to Omagh road, measuring 100m by 20m deep through the upper half of the Killucan ridge core, shows two principal lithofacies associations (LFAs): LFA 1 The lower LFA, consists of a 4m deep arch-shaped unit of massive, crudely imbricated boulder gravels draped on either side by pebble gravel beds. Palaeoflow, inferred from imbrication and bed geometry, was to 270°N. LFA 2 The upper LFA, comprising 90% of the section, consists of a stacked sequence of a fining upward sequence of trough cross-bedded pebble to cobble gravel, planar cross-bedded gravels (<4m deep) and laterally discontinuous lenses of planar cross-bedded sands (<1m thick). Contacts between the units are sharp and undulating along the mean palaeoflow direction (300°N), inferred from cross-bedding dip orientation. One laterally discontinuous 2-3m deep unit consists of openwork, planar-bedded cobble gravels dipping at 25° to 90° north. Killucan Delta: Exposure 2 A small-scale pit (267700 379200) on the southern flank of the ridge exposes a 40m by 4m deep section through the upper beds of the ridge core. The exposure consists of one LFA, consisting of large-scale trough cross-bedded sands and pebble to cobble gravel occurring in sharply defined channels. Palaeoflow, from trough bedding orientations, was to 40°N. C. Lough Doo Eskers The deposit at Killucan is joined from the southwest by a 1km long system of reticulate, beaded sharp-crested ridges approximately 20-25m high which lower in elevation northwards from the foothills of the Evishanoran Mt (267100 377700). The general orientation of the branching ridge complex is 5°N. PHASE 3: CAM LOUGH ESKERS AND KAME TERRACES, EVISHANORAN, SULTAN, BARLEYHILL AND MURNELLS (MALINN) DELTAS Located on the western and southeastern foothills of the highlands formed by Evishanoran and Cregganconroe mountains to the immediate south of the Ballinderry valley, is a complex consisting of four deeply dissected large scale, steep-sided landforms with extensive flat-tops which occur at 235m O.D. A. Cam Lough Eskers The deposits at Evishanoran (0.9km2) and Sultan (2.9km2) (265500 377500) are bordered to the south by a steep (>25°) slope forming the northern margin of a basin containing Cam Lough (266800 376800). A north/south trending, generally linear belt of <10m high hummocks and sharp-crested ridge segments join the deposit at Evishanoran on its southern margin, continuing generally southwards for 2km along the eastern foothills of Cregganconroe Mountain (elevation 290 m), towards the Pomeroy valley. The basin lowlands containing the enclosed depression filled by Cam Lough are enclosed to the west by the steep slope of a sharp-crested, hummocky cross-valley ridge which extends from the foothills of Cregganconroe to the deposit at Sultan. In the area to the west and southwest of this ridge and the col between Scalp (263500 374400) and Cregganconroe, approximately 1.45km2 of flat-topped, dissected terraces increase stepwise in elevation southwestwards. Enclosed, water filled depressions are contained on the terrace surfaces. B. Evishanoran Delta The Evishanoran delta forms a large (0.9km2), dissected terrace with a flat-top occurring at 235m O.D. which is perched on the slopes of Evishanoran mountain. The southern margin of the deposit which forms the northern margin of the Cam Lough basin, has been extensively quarried. Three large commercial sand and gravel extractions, with only one presently active, occur in the deposit. Evishanoran: Exposure 1 An exposure resulting from commercial aggregate extraction (266400 377700) consists of a 180m by 25m deep section through the core of the flat-topped ridge. The entire exposure is comprised of one LFA: LFA 1, Pebble-gravel foresets The lower 22m of the section consists of well-developed large-scale planar cross-beds dipping at >25°. Beds are separated by sharp contacts. These are overlain in places by 2-3m of planar, low-angle beds in sharp, irregular contact with the underlying beds. Planar cross-beds consist predominately (>60%) of well-sorted pebble gravel with occasional fining upward and coarsening upward sequences of pebbly sand and cobble-gravel. Individual planar cross-beds reach thicknesses of over 1m. Above a sharp, irregular contact, the flat-lying planar beds cross-cutting the cross-beds consist of <10cm thick, less well-sorted cobble to pebble gravel. These beds are absent in places, with the planar cross-beds forming the upper (ground) surface. Palaeoflows, taken from planar-cross beds vary between 270° to 300°N changing laterally (northwestward) to 210°N. No glaciotectonic structures are visible. Evishanoran: Exposure 2 The second, older commercial quarry is largely unworked and poorly-exposed. Sediments consist of large-scale, low-angle planar cross-bedded well-sorted sand and pebble to cobble gravel with occasional beds of massive boulder and sand admixtures. The sequence contains a large (>8m a-axis) slab of angular limestone rock which has convoluted the beds occurring below it, and is draped by well-sorted sand. The sequence generally fines laterally northwards, in the direction of Exposure 1. Palaeoflows, taken from the apparent dips of cross-beds were also generally in this direction, showing however a progressive change to the northwest with increasing elevation in the section. C. Murnells Delta A flat-topped ridge, occupying 1.4km2, occurs on the eastern margins of the Evishanoran/Cregganconroe highlands. The ridge is dissected by a north/south trending, steep-sided flat-bottomed channel which terminates at the margin of the flat-topped terrace at Cavanoneill. One partially grassed exposure occurs in the ridge. Murnells Delta: Exposure A disused commercial pit (268900 376300) exposes a partially grassed section 80m long by 10m deep in the northeastern flank of the Murnells flat-topped ridge. The exposure, through the upper beds of the ridge is composed of one LFA: LFA 1, Planar cross-bedded pebbly sands The sediments consist of well-developed, large-scale planar cross-bedded pebbly sand and gravel dipping at 25°. Beds, ranging in thickness from 5cm to >1m, contain laterally discontinuous pebble clusters fining into well-sorted medium to coarse sand. Contacts between beds are sharp. No glaciotectonic structures were visible. Palaeoflow, based on cross-bedding orientation, was to 15°N. PHASE 4: DUNNAMORE, GORTACLADY, CAVANONEILL AND KILDRESS TERRACES A. Gortaclady, Cavanoneill and Kildress Terraces Three dissected, low-angle to flat terraces centred on Gortaclady (269300 376900), Cavanoneill (270500 376700) and Kildress (271800 378000), occur between 220m and 200m, 190m and 180m, and 140m and 130m O.D. respectively to the east and northeast of the Evishanoran/Cregganconroe highlands. The Gortaclady and Cavanoneill terraces have remained relatively intact with the latter containing an extensive flat-top occupying 4.25km2. A 0.75km2 raised bog has developed on the flat-top. The Kildress terrace, located immediately northeast of the Cavanoneill terrace, extends northeastwards into the hummocky gravels occupying the centre of the Ballinderry river lowlands. The rolling topography consists of terrace remnants occurring amongst bedrock ridges and generally southwest/northeast trending glaciofluvial channels. B. Dunnamore Terrace An area of dissected valley-fill deposits occupying 1.2km2 occurs along the valley floor axis of the Ballinderry river near Dunnamore. The deposit is bordered to the east by a sharp-crested cross-valley ridge at Tulnacross (271200 380700) and steep, frontal slopes to the west. On the northern edge of the river, on the rising slopes of Evishbrack Mt (270100 382800) is a small (0.6km2) topographic flat located at 55m O.D. Dunnamore: Exposure An exposure occurs in the terrace flank (268400 380500) near Dunnamore. The exposure in an abandoned pit, measures 8m deep by 20m long, and consists of two laterally interbedded lithofacies. The eastward (downvalley) sequence consists of well-sorted horizontal and ripple laminated fine to medium sands contained in broad channels 10-15m across by <1m deep. The sequence contains a 1m deep lens of well-sorted, inversely graded cobble gravel. Channels appear to dip at low angles (<5°), with ripple orientations giving mean palaeoflows to 330-350°N. The well-sorted sands grade laterally (westward) into the second lithofacies, consisting of a wedge of interbedded sands and cobble gravels. Palaeoflow during deposition of the gravel was to 225°N. PHASE 5: DRUMSHAMBO AND MUNTOBER RIDGES A cross-valley ridge, bisected by the lowlands of the Ballinderry river valley, extends NE/SW from Muntober (274600 381100) to Drumshambo Glebe (272800 378700), a distance of approximately 4km. The central portion, forming a zone along the course of the Ballinderry river and the topography of the valley bottom westward as far as Dummanore and Killucan, is comprised of hummocky, steep-sided gravel mounds. The Muntober ridge is steep-sided, particularly on its eastern flank and rises to a maximum elevation of 80m O.D. The northern portion of the ridge is undulating and smooth-crested, whereas a 0.5km portion forming the southern tip is distinctly thinner, sharp-crested with pronounced beading along its length. An exposure occurs in a commercial pit in the northern portion of the ridge. Muntober Ridge: Exposure A 100m long by 12m deep exposure occurs transverse and longitudinally to the core of the northern, smooth-crested ridge section. Two principal LFAs are exposed: LFA 1 LFA 1 consists of stacked small-scale 1.5m deep planar cross-bedded sets of poorly-sorted cobble gravels below a sharp, undulating contact with well-sorted, finely-bedded to massive sands. Up-sequence, the finely-bedded sands grade into stacked, repeated units of horizontally laminated beds followed by a-type then climbing b-type ripples. Pebble gravel cross-beds dip at 20° to 340°N. LFA 2 LFA 2 consists of channelised, trough cross-bedded sands and pebble to cobble gravels and 3-4m thick beds of poorly-sorted, massive, crudely imbricate cobble gravels. A crudely linear zone of bedding disturbance (shear-plane) strikes and rises to the northwest, along 60/240°N, sub-parallel to the axis of the ridge. The shear-plane dips at a high angle to 155°N. Palaeoflow, indicated by cross-bedding progradation direction, was to 225°N. PHASE 6: KNOCKALEERY RIDGE A large-scale, linear, sharp-crested cross-valley ridge, which rises up to 188m O.D. and is 2km long, is located to the south of the present course of the Ballinderry river between (274600 377900) and (272400 376300). The sides of the ridge are steep, the eastern slope exceeding 25°. The ridge forms a visually prominent feature in the lower reaches of the valley, rising over 40m above the valley floor and marks the eastern margin of the Ballinderry large-scale glaciofluvial landforms. Several large commercial pits exist in the ridge core and flanks. Knockaleery Ridge: Exposure (Reed's Pit) An exposure in a large-scale commercial aggregate operation exposes a 200m long by 30m deep section through the core of the southwestern end of the Knockaleery cross-valley ridge and consists of two principal LFAs: LFA 1 In a pit-face on the southeast of the ridge core, a 10m long by 3.4m deep section occurs in massive, polymodal clast-supported boulder gravel. They contain a block of well-sorted, planar-bedded coarse sand in sharp, irregular contact with the boulder-gravel matrix. Boulder clasts are up to 70-80cm long and edge-rounded. LFA 2 The northwestern pit-face is oriented sub-parallel to the ridge and consists of low-angle, planar cross-bedded, predominately well-sorted, finely-bedded to laminated medium sand. Many high angle shears occur over a range of lateral and vertical scales. They strike along 120/300°N dipping at 15-20° to 210°N. Sandy cross-bed sets, of over 20m vertical thickness, contain 6-8m deep sequences of very well developed ripple sequences. The sands are interbedded laterally with sequences of interbedded, well-sorted pebble gravels and pebbly sands. No junction between LFA 1 and 2 was exposed. Palaeoflows, measured from ripple orientations and bedding structures vary laterally and vertically through the section, with a bimodal preferred orientation to the north and southwest. PHASE 7: BLACK HILL RIDGE, COOKSTOWN ESKER AND DRUMNARD OUTWASH A. Black Hill Ridge A 1km long, 35m high and 250m wide ridge is located immediately west of Cookstown (279900 377100). The ridge is bordered to the west and southwest by a low-lying topographic flat at Drumnard, 4.2km2 in area. A small-scale temporary exposure consisted of planar-bedded, poorly-sorted sand interbedded with pebble gravel. B. Cookstown Esker A 2km long ridge system with both east/west and north/south oriented elements is located to the southeast of the Black Hill ridge in the area between Derryloran (279400 376600), Rockhead Hill (281200 375200) and Drummond Wood (282800 376000). The ridge decreases in elevation to the north and west, with a corresponding change in morphology from mounded, to steep-sided and sharp-crested, to hummocky.
Notes:
INTERPRETATION Based on the structure of the description of the deposits, the interpretation follows a relative chronology of deposition, with events described from earliest to latest. The interpretation outlined below broadly follows the detailed work and conclusions reached by Dardis (1982). PHASE 1: DAVAGH ESKER The cross-valley ridge at Teebane (267700 380500) is contiguous with the northward trending Davagh Esker ridge, which terminates at 210m, an increase in elevation of 60m on the western margin of the Lough Fea platform. The small-scale exposure and regional evidence suggest that the ridge is a result of deposition from meltwater under high hydrostatic pressure in a closed conduit channel of an ice mass occupying the western end of the Ballinderry valley and which was being fed by meltwater supply from the south. PHASE 2: CREGGAN RIDGES, KILLUCAN DELTA AND LOUGH DOO ESKERS Down- and backwastage of the ice mass proceeded from north to south, deglaciating the westernmost reaches of the Ballinderry valley, with an ice-margin near Creggan. The ice mass split at this time forming lobes which backwasted westward into the Owenreagh valley and resulted in the outwash plain at Creggan, southward towards the Omagh Basin along the lowlands now occupied by the Grannagh Burn (262400 375700) and eastward into the Ballinderry valley. A proglacial ponded waterbody developed in the deglaciated area between the lobes, allowing the formation of the small flat-topped delta at Creggan by ice retreating westward. Further phased ice recession eastward formed the ridges described at Creggan. The waterbody accumulated to an elevation of 180m O.D. in the proglacial area, dammed by the ice margins and the Sperrin uplands further north. This allowed the aggradation of a large-scale deltaic deposit at Killucan. Meltwater flow and hence sediment supply continued to originate from the south, resulting in the deposition of the reticulate subglacial esker ridge system at Lough Doo. PHASE 3: CAM LOUGH ESKERS AND KAME TERRACES, EVISHANORAN, SULTAN, BARLEYHILL AND MURNELLS DELTAS The large-scale flat-tops of the glaciolacustrine sediments deposited on the northwestern and eastern flanks of the highlands of Evishanoran Mountain (267100 377500) and Cregganconroe (265800 375200) record the presence of a proglacial ponded waterbody at 235m O.D. in the deglaciated lowlands to the northwest and east. The palaeoflow of meltwater entering the lake, the ice-contact slopes facing southwards at Cam Lough and the presence of esker ridges immediately to the south of the deposits at Cam Lough support this hypothesis of a proglacial lake, subglacial feeder channels and ice-marginal delta. The Evishanoran/Cregganconroe highlands formed a topographic divide between late-glacial ice lobes. The topographic bedrock highs separated a lobe situated on the highland which retreated generally eastward from the Scalp (263500 374400)/Cregganconroe (265800 375200) col (forming the kame terraces containing the waterfilled kettle-holes of Lough Mallon and Black Lough), from one which retreated generally southward, through the Scalp/Cregganconroe col into the Pomeroy valley (See Key Site 482 - Pomeroy Valley). PHASE 4: DUNNAMORE, GORTACLADY, CAVANONEILL AND KILDRESS TERRACES Ice retreat continued eastward into the lowlands of the Ballinderry river valley. The large topographic flats at Gortaclady (located between 220 and 200m O.D.), at Cavanoneill (located between 190 and 180m O.D.), and the remnant terrace at Kildress represent fluvioglacial outwash terraces deposited from meltwater issuing from the highlands to the west. Dardis, (1982) infers that they terminated adjacent to, and thus had their lower elevations controlled by, successively lower ponded waterbodies, which must have extended into the Ballinderry valley lowlands. The terraces have been deeply dissected by post-depositional erosion, possibly supplying the majority of the sediment for the successively lower terrace. The small flat at Dunnamore may represent the deposition of fine sediment into a proglacial lake with an elevation of at least 180m as a low-angle fan-delta, possibly from an ice-margin located at Tulnacross (281800 379900), marked by a cross-valley ridge (elevation 178.8m, Dardis, 1982). Alternatively, it may represent the upper deposition surface of a Gilbert-type delta aggrading in a lake of lower elevation (165m O.D.) and lesser extent than the one into which the Killucan delta prograded (elevation 180m O.D.). The exposure at Dunnamore shows the terrace to consist of well-sorted, fine sediment containing ripple lamination bedding structures representing deposition in a subaqueous, low-energy, ice-distal environment and the absence of fluvial (topset) deposition. It is inferred that the former explanation is the more likely, with the flat-top at this location resulting from post-depositional subaerial erosion. PHASE 5: DRUMSHAMBO AND MUNTOBER RIDGES The dissected cross-valley ridge complex located between Drumshambo and Muntober is inferred to be partly of glaciotectonic origin, demonstrating a small-scale ice-margin advance during the eastward, phased retreat. From the sediment sequence exposed at Muntober, it is argued that a prograding glaciolacustrine sequence (LFA 1) was overthrust along a zone of ENE/WSW striking shears by part of the upper association (LFA 2) due to an ice marginal advance and increased ice pressure on the eastern (ice-proximal) slope. The glaciotectonically sheared sediments are bordered to the southwest, parallel to the strike direction of the shears, by an undulating, sharp-crested ridge, which, from morphology alone, indicates formation by the coalescence of small-scale ice-marginal, possibly subaqueous fans. Poor exposure of the sediments at Drumshambo did not clarify the ridges composition, but from regional evidence it is inferred to share the same glaciolacustrine origins. As possibly glaciotectonic ridges, they do not provide a precise figure for the ponded waterbody depth at these sites. PHASE 6: KNOCKALEERY RIDGE The Knockaleery ridge is inferred to have formed from the coalescence of subaqueous fans, originating from multiple ice-marginal point sources. After deposition, during which time the ice margin was in a period of temporary fluctuation, a small ice-marginal advance deformed and sheared the sediments, the shear strike-lines oriented sub-parallel to the orientation of the ridge. The steep slopes on the ridge's eastern flank are probably of ice-contact origin and support the inferred direction of ice-pressure. PHASE 7: BLACK HILL RIDGE, COOKSTOWN ESKER AND DRUMNARD OUTWASH The Black Hill ridge represents either a glaciotectonically produced ridge related to a small-scale ice-marginal advance or a cross-valley moraine ridge produced at a temporary ice-marginal halt. The flat-lying area of Drumnard outwash indicates the burial by a sandur type outwash plain of deposits related to a relatively continuous and rapid ice-margin back-wastage. The Cookstown esker ridge system indicates a generally east to west meltwater flow towards the Ballinderry river valley, from a source in the Lough Neagh lowlands. The eskers may be related to a small esker-like ridge segment located 5km upvalley at Drum Manor (275900 377800) and a segment located at Annaghmore, 1km southwards. Ice Advance and Decay Summary The topographical, morphological and sedimentological evidence suggest the following pattern of ice mass advance and decay: 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 (Key Site 477). The ice-pressure must have been restricted by the upstanding bedrock, thus concentrating erosive power on the granite outlier. The flow pattern resulted in the southeast/northwest drumlin orientations occurring in the broad lowland zone south of Drum Manor, to the east of the highlands and the high proportions of granite clasts found in the sediments (Dardis, 1982). 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 (266900 389200)/Evishbrack Mt. (270100 382800), and Evishbrack /Beltonanean Mt. (271500 382700) and Oughtmore (272400 383700)/Fir Mt. (274700 385400). Further downwastage resulted in the formation of four lobes in the upper Ballinderry river valley region. One lobe backwasted towards the west, forming the Creggan outwash plain. One backwasted eastward along the Ballinderry river valley, separated by the rising bedrock slopes of Slievemore (268800 378600) and Evishanoran Mt. from the third lobe which backwasted towards the highlands of Cregganconroe. IMPORTANCE The complex is rated as highly scientifically important. This is due to: A. 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; B. The occurrence and exposure of cross-valley ridges, formed as a result of glaciotectonic stresses applied to proglacially deposited sediments; C. 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 ice towards the Bann valley lowlands from the eastern flanks of the Sperrin mountains; D. Excellent examples of flat-topped, Gilbert-type deltas provide firm evidence that late-glacial lake levels of 235, 188, 180 and 140 occurred in the deglaciated margins of the Sperrin mountains; E. 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; F. The complex contains an excellent exposure of classic Gilbert-type delta foresets and topsets at Evishanoran; and G. an excellent example of glaciotectonic shears at Muntober. 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 This site is also a Site of Local Nature Conservation Importance. See Key Site 701 - Ballinderry.

Keywords
Relations:	Glacial deposit, Glaciotectonic
Geomorph:	cross-valley moraine, delta, esker, flat-topped delta
Paleoenv:	delta

Access
Management:
As a regional centre for the production of concrete products, the extensive deposits of the Cookstown/Ballinderry river area have undergone prolonged large-scale commercial extraction, resulting in significant landscape despoliation. One location, Cam Lough, has a potentially high educational value, providing excellent examples of deglacial landform associations and glacigenic topographic diversity in a rural, picturesque, highland area. Additional commercial aggregate extractions in the significant deposits of the area will however further detract from the scientific and aesthetic value of the area which is already the location of a large pit and spoil heap. Similarly, large sand and gravel pits on the northwest facing flank of the prominent Knockaleery ridge, and in the Northwestern end of the Killucan delta have resulted in visually obtrusive spoiling of the view from the A505 Cookstown to Omagh road.

Access

Management:

As a regional centre for the production of concrete products, the extensive deposits of the Cookstown/Ballinderry river area have undergone prolonged large-scale commercial extraction, resulting in significant landscape despoliation. One location, Cam Lough, has a potentially high educational value, providing excellent examples of deglacial landform associations and glacigenic topographic diversity in a rural, picturesque, highland area. Additional commercial aggregate extractions in the significant deposits of the area will however further detract from the scientific and aesthetic value of the area which is already the location of a large pit and spoil heap. Similarly, large sand and gravel pits on the northwest facing flank of the prominent Knockaleery ridge, and in the Northwestern end of the Killucan delta have resulted in visually obtrusive spoiling of the view from the A505 Cookstown to Omagh road.

References (6)
Charlesworth, J.K., 1926. The Evishanoran Esker, Co. Tyrone Geological Magazine, vol. 63, pp.223-225.
Colhoun, E.A., 1972. The deglaciation of the Sperrin Mountains and adjacent areas in counties Tyrone, Londonderry and Donegal, Northern Ireland Proceedings of the Royal Irish Academy, vol. 72 pt. B, pp.91-147.
Dardis, G.F., 1982. Sedimentological aspects of the Quaternary Geology of South-Central Ulster, Northern Ireland (Thesis), pp.422 Unpublished PhD Thesis, New University of Ulster.
Dardis, G.F., 1985. Genesis of Late Pleistocene Cross-Valley Moraine ridges, South-Central Ulster, Northern Ireland Earth Surface Processes and Landforms, vol. 10, pp.483-495.
Dardis, G.F., 1986. Late Pleistocene lakes in south-central Ulster, Northern Ireland Irish Journal of Earth Sciences, vol. 7, pp.133-144.
Gregory, J.W., 1925. The Evishanoran Esker, Tyrone Geological Magazine, vol. 62, pp.451-458.

Record type:	ESCR report
Entered by:	E M Porter

Enlander, I., Dempster, M. & Doughty, P., 2026. Ballinderry - deglacial landscape, County Tyrone, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=480. Accessed on 2026-11-04.