ESCR - Fintona Hills Complex - Crockfadda outwash-moraine system

Earth Science Conservation Review

Summary Full report
Fintona Hills Complex - Crockfadda outwash-moraine system	Fermanagh, Tyrone

Site number:	495
ESCC:	IS
Locality Type:	Inland exposure	Status:	TBC
Grid Reference:	H346544,H390565 End(s) of linear site, Not Entered
Google maps:	54.43742,-7.46675
County:	Fermanagh, Tyrone	Council area:	Fermanagh & Omagh District Council
Period:	Quaternary

Site Description
Description:
This area, extending from Crockalusky (H346544) to Crocknafarbrague (H390565) (5km long), is characterised by aligned moraine ridges and flat, dissected outwash surfaces. Ridges are generally aligned NE/E-SW/W, parallel to the Fintona Hills to the south. Ridges are up to 0.9km long, 0.3km wide and 20m high, and are often closely spaced (50m), separated by deeply incised and narrow meltwater channels. Ridges are also related to feeder eskers transferring material from west to east (see Key Site 494 - Ballinamallard Esker), kettleholes, proximity of bedrock surfaces, and intervening localised outwash spreads. There are two main exposures in the outwash and ridge sediments. The Meencrim pit (H377558) is a mostly disused sand pit and shows a range of rhythmically-bedded, well-sorted fine-grained sediments with some glaciotectonic deformation. Facies description This exposure (10m long and 2m high) is characterised by laterally discontinuous (4m) and interbedded units (10-40cm thick) of well-sorted granule to clay-sized particles within broad channels. Sand facies are well-bedded with dm-scale foresets, climbing ripples, clay drapes, water escape structures and rhythmically-bedded units. Crossbeds generally dip 20§ to 020§. Ripples are asymmetric and have a parabolic climb. Minor compressional faults generally strike north-south and record push to the east. Rhythmically-bedded couplets are 10-15cm thick and comprise a lower component of massive fine sand to silt, a middle component of normally graded cross laminated fine sand to silt, and an upper component of a thin and undulatory, slightly rippled mud drape. Facies interpretation This exposure records low energy subaqueous sedimentation influenced by local current activity and seasonal meltwater events. This is evidenced by the dominance of well-sorted and interbedded facies with well-developed unidirectional palaeoflow indicators. The physiographic location of this site favours a local, topographically-controlled upland water body, probably bounded by bedrock, in a proglacial setting. Proglacial deposition is inferred from its relationship to the adjacent esker-moraine system and compressional fault alignment, which is consistent with ice marginal push from the west associated with moraine build-up. Also, the record of water flow towards the NNE may either reflect a local directional feature or may be related to a water source from the Fintona Hills to the south. Regional evidence for south-to-north water flow includes limestone erratic blocks that have been possibly carried over across the watershed by glacial lake drainage (see Key Site 485 - Tempo). This is supported by the presence of surficial limestone boulder erratics near Crocknaconspody, 1.5km southeast of this site, at H397548 and H393552. Ridge sediments are seen in the Crocknaboortan exposure (H372551) 0.5km southwest of the Meencrim pit. Facies description This exposure (25m long and 5m high) is characterised by dipping units (0.4-0.6m thick) of sorted clast- and matrix-supported massive and occasionally normally-graded beds composed of sand to pebble gravels (<15cm diameter). Dispersed boulders (<30cm diameter) also occur towards the centre of the exposure. These beds are vertically stacked, laterally discontinuous (to 6m) and have transitional contacts. Normal and reverse faulting striking approximately north-south is seen. A clastic dike (0.2m wide, 1.5m high) dissects sediments on the ridge flank. Facies interpretation This sediment sequence is interpreted to reflect an ice-marginal environment affected by ice melt-out and post-depositional water migration processes. The east-west oriented ridge landform, following Warren and Ashley (1994), is interpreted as a moraine supported in an ice-walled channel. This is shown by the complex interbedded association of sand and gravel facies, disturbed by marginal and subjacent ice collapse which resulted in high-angle extensional faulting, and promoted water migration and escape structures, sediment resorting and winnowing of fine matrix sediments. These deformation processes are more marked on the ridge flanks, which is consistent with removal of ice support. Water escape structures may also have been promoted by groundwater flow generated by freezing-front migration within the sediment body (McRoberts and Morgenstern, 1975) (see Key Site 485 - Tempo). The ridge itself may have been supported by both detached ice megablocks (10m3 dimensions) and by the main ice mass. This may be evidenced by deep inter-ridge peatland-filled kettleholes. The close morphological similarity between ridges of morainic and esker origin has been noted elsewhere in Ireland (Warren and Ashley, 1994).
Notes:
For site specific information on other sites within the Fintona Hills Complex see the following sites: Key Site 494 - Fintona Hills Complex - Ballinamallard Esker Key Site 496 - Fintona Hills Complex - Dungoran kame-esker-outwash system Key Site 497 - Fintona Hills Complex - Dromore outwash-moraine system Key Site 498 - Fintona Hills Complex - Newtownsaville Esker For overview information and references on the Fintona Hills Complex see the following site: Key Site 484 - Fintona Hills Complex - Overview 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 718 - Crockfadda.

Keywords
Rocks:	Gravel, Sand
Relations:	Glacial deposit
Geomorph:	moraine, outwash


Record type:	ESCR report
Entered by:	E M Porter
Last updated:	6 Jun 2005

Enlander, I., Dempster, M. & Doughty, P., 2026. Fintona Hills Complex - Crockfadda outwash-moraine system, County Fermanagh, Tyrone, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=495. Accessed on 2026-11-06.