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Earth Science Conservation Review
| Cole Bridge Stream, Fivemiletown | Tyrone |
| Site number: | 201 | File Number: | H45 |
| ESCC: | EO | ||
| Locality Type: | Stream section | Status: | ESCR |
| Grid Reference: | H4452 1 km square | ||
| Google maps: | 54.41513,-7.32225 | ||
| County: | Tyrone | Council area: | Mid Ulster District Council |
| Period: | Carboniferous | ||
| Stages: | Tournasian | ||
| Lithostrat: | Ballyness Formation, Clogher Valley Formation, Tyrone Group | ||
| Site Description | |
|---|---|
| Highlights: | |
The basal beds of the Carboniferous sequence in Co. Fermanagh are only exposed northeast of Enniskillen and on the north side of the Clogher Valley. The Cole Bridge Stream section is the stratotype for both the Ballyness and Clogher Valley formations. A variety of fossils obtained from the latter formation confirm its Courceyan age. | |
| Description: | |
The Cole Bridge Stream is one of numerous tributaries of the east-flowing River Blackwater that drains Ballyness Mountain and the south flank of the Fintona Block, in Co. Tyrone. The section is located about 4.25km north of Fivemiletown on the boundary between Cole and Edergole townlands and extends from Cole Bridge (H4460 5190) in the south for over 600m to the north-northwest, to the confluence point of two streams just upstream of the bridge at H4432 5241 leading to the bungalow on the west side of the stream. Griffith (1970) described this section and recorded the presence of marine fossils in the upper part of the sequence. At the base of the sequence, at the north end of the section are bright red sandstones and pebbly conglomerates, with abundant quartz pebbles, of the Ballyness Formation. In Edergole Townland and on Ballyness Mountain, north of this section, the Ballyness Formation has an outcrop width of about 2km and, at its base, is supposed to rest unconformably on the Upper Devonian Fintona Group. Red sandstones and conglomerates are exposed in the rough track leading down to the river on the north side of the farm-road-bridge and in the river under, and north of the bridge. The transition upwards in the top part of the Ballyness Formation is from red-purple coarse sediments to interbedded pink and pale green to fawn and finally to green and blue-grey pebbly sandstones, coarse to fine-grained calcareous and non-calcareous sandstones and soft medium grey calcareous siltstones. The red coloration is completely absent in rocks located more than 5m south of the farm-road-bridge but they still belong to the Ballyness Formation. Some 50m south of the farm-road-bridge is a long dip slope, inclined south at 20 deg., formed by the top surface of a 0.12m thick grey, very calcareous, fine-grained silty sandstone. South of this slope, in the west bank, is a low cliff formed of about 2.5m of interbedded grey, fine to medium-grained sandstones, thin (0.001-0.003m) green and grey silty shales and mudstones, and one lenticular bed, 0.01m thick, of silty micrite and green shales. This bed is the first indication of incoming marine conditions in this part of Co. Tyrone. A thin mudstone bed located 0.5m below the top of this section contains a sparse miospore assemblage including Retusotriletes incohatus and Calamospora spp. The former species is usually associated with late Devonian-early Carboniferous assemblages but the absence of L. pusilla, suggesting a pre-Vis‚an age, is more significant. Above this section is a small exposure gap representing about 1m of strata. Immediately above the gap are pale grey peritidal micrites and dark grey sandy siltstones, siltstones and micaceous shales, the basal beds of the Clogher Valley Formation. The micrites are unfossiliferous but the shales frequently contain well-preserved miospores including the following forms: Anaplanisporites centrosus A. delicatus Aurorospora asperella A. corporiga A. macra Baculatisporites fusticulus Bascaudaspora submarginata Convolutispora circumvallata C. major C. permixta Crassispora catenata C. trychera Discernisporites sullivanii Grandispora echinata Knoxisporites literatus Lophozonotriletes tuberosus cf. Lycospora sp. (very rare) Plicatispora scolecophora P. quasilabrata Prolycospora rugulosa (common) Retusotriletes crassus R. incohatus Rugospora minuta R. polyptycha R. vieta Schopfites claviger S. cf. claviger S. delicatus Spelaeotriletes pretiosus S. resolutus Umbonatisporites distinctus Vallatisporites vallatus V. verrucosus Verrucosisporites cf. scurrus This assemblage clearly indicates an assignment to the CM Zone. However the presence of cf. Lycospora sp. may indicate a proximity to the CM-Pu zonal boundary and thus a late Tournaisian (early Chadian), rather than Courceyan, age. During the remapping of the Cole Bridge Stream by the GSNI in 1964 a small collection of brachiopods and corals was made from the interbedded carbonates and shales, located about 430m north-northwest of Cole Bridge and 15m above the unexposed formation base at H4440 5227. Brachiopods present include: Cleiothyridina glabistria Macropotamorhynchus mitcheldeanensis Spinocarinifera bassa These are associated with the small, solitary coral: Zaphrentites delanouei All of these fossils first occur in either the early or middle Tournaisian and only the range of C. glabistria extends into the early Vis‚an. On this evidence it seems likely that a Tournaisian age for the Clogher Valley Formation is correct. Despite repeated attempts no further macrofauna could be collected from this locality or from the formation in general. | |
| Importance: | |
The Cole Bridge Stream section is probably one of the most complete through the Lower Carboniferous "basal clastics" on the north side of the Clogher Valley. It exposes the top part of the Ballyness Formation and the lower part of the overlying Clogher Valley Formation, in which occur CM Zone miospore assemblages and a very sparse coral-brachiopod fauna of Tournaisian age. | |
| Interpretation: | |
Sedimentary rocks exposed adjacent to the position of the (unexposed) contact between the Ballyness and Clogher Valley formations were deposited firstly as non-marine red-beds in a proximal position on an alluvial fan and reflect a gradual, but rapid transition to aqueous environments. The colour change from red-purple to grey and green in the clastic sediments at the top of the Ballyness Formation was induced by the change from an oxidising to a reducing (water-saturated) depositional environment. The incoming of brackish water, peritidal and quasi- marine conditions occurred rapidly and was coincident with the onset of deposition of peritidal carbonates at the base of the Clogher Valley Formation and, somewhat higher in the formation, of argillaceous and silty, very sparsely fossiliferous, very fine-grained packstones-wackestones. | |
| Notes: | |
For information on other sites in Subarea-2 see; Key Site 1175 - Subarea-2; Lisnaskea-Fivemiletown. | |
| Keywords | |
|---|---|
| Rocks: | Mudstone, Sand, Sandstone, Shale, Siltstone |
| Fossil Groups: | Brachiopod, Coral, Miospore |
| Fossil List: | Cleiothyridina glabistria , Prolycospora rugulosa , Zaphrentites delanouei |
| Relations: | Marine sediments |
| Access | |
|---|---|
| Approach: | The section is located about 4.25km north of Fivemiletown on the boundary between Cole and Edergole townlands and extends from Cole Bridge (H4460 5190) in the south for over 600m to the north-northwest, to the confluence point of two streams just upstream of the bridge at H4432 5241 leading to the bungalow on the west side of the stream. |
| References (2) | |||
|---|---|---|---|
| Griffith, A.E., 1970. A review of Upper Old Red Sandstone and Tournaisian rocks in Northern Ireland. International Geological Congress, vol. 1970 pt. 2, pp.837-841. | |||
| Oswald, D.H., 1955. The Carboniferous Rocks between the Ox Mountains and Donegal Bay. Journal of the Geological Society of London, vol. 111, pp.167-186. | |||
| Map(s): | GSNI (1983) 1:50,000 Sheet 46 (Clogher). | ||
| Record type: | ESCR report | ||
| Entered by: | Doughty, P.J. | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Cole Bridge Stream, Fivemiletown, County Tyrone, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=201. Accessed on 2026-11-06. |
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