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Earth Science Conservation Review
| Eastern Garron Plateau, County Antrim | Antrim |
| Site number: | 1169 | ||
| ESCC: | IC | ||
| Locality Type: | Karst | Status: | ASSI |
| Grid Reference: | D2923 Approximate | ||
| Google maps: | 55.03809,-5.98218 | ||
| County: | Antrim | Council area: | Mid & East Antrim Borough Council |
| Period: | Quaternary, Tertiary, Cretaceous, Jurassic | ||
| Stages: | Eocene, Holocene, Palaeocene, Santonian, Toarcian | ||
| Lithostrat: | Antrim Lava Group, Lias Clay, Upper, Ulster White Limestone Formation | ||
| Site Description | |
|---|---|
| Highlights: | |
Black Burn Cave is the only known explored, extensive, active cave system developed in Cretaceous Limestones in Ireland. It is probably the most extensive karst drainage system developed in Cretaceous carbonates in the United Kingdom. | |
| Introduction: | |
An active river cave system was discovered at Carrivereagh, Carnlough, County Antrim in 1984. This is the only major cave system in the Ulster White Limestone Formation which has been explored to date. The cave was unsurveyed and the karst drainage patterns in the Carnlough - Garron karst were untraced. As part of the ESCR programme T. Fogg and J. Kelly were contracted to survey the cave, attempt water tracing experiments to determine karst hydrological connections and to prepare a report on the Garron Karst for possible ASSI designation. History of Exploration: A significant cave system in Carrivereagh Townland was discovered by a party of canoeists in 1984. The cave was initially explored, by Maurice Neill and Rev. George Pitt of the Reyfad Group in July 1984, for ~150m to a sump. In September 1984, Mark Campbell, Tim Fogg and Pam Fogg returned with diving gear to attempt to pass this sump. Water levels had fallen and a short duck was encountered at the sump. This was quickly passed but a sump proper was encountered after a further 40m. Beyond this, a Main Stream Passage was reached and four further sumps were passed with a further 180m of passage explored. This remains the furthest point explored in the cave. The cave was visited by Tim Fogg and John Kelly in August 1994 who discovered the old entrances hopelessly blocked by flood debris. They were able to locate a new entrance and explored a new series of pitches into the known cave. The cave was surveyed to the duck, which was discovered to have disappeared due to low water conditions. It was also discovered that a sizeable inlet to the system enters via an aven at this point and that boulders washed in via this inlet had blocked the passage making it impassable. | |
| Description: | |
I - Hydrology There are a number of streams draining the east facing scarp of the Garron Plateau and a number of these are known to sink into the Ulster White Limestone. The most significant speleologically, is Black Burn which has an active associated cave system. The water sinking in Black Burn has been chemically traced to Foaran Rising. In addition, two other rivers to the north of Black Burn are also known to sink into the White Limestone, at or adjacent to the Basalt - White Limestone contact. These additional sites are located in Drumnasole and Ballyvelligan townlands. The former is similar to the Black Burn sink, the stream sinking in a boulder strewn pool at the base of a waterfall (D28822197). In the latter case the stream sinks gradually over ~200m of stream bed, after passing the Basalt - White Limestone contact (D289222). These latter two sites remain untraced but are presumed to drain to Foaran Rising. (i) Water Tracing Experiments Water tracing experiments were not carried out in connection with the ESCR review as the Garron area was being investigated by Mr. Stephen Barnes as part of an M.Sc. research project at the time chosen as being most suitable for tracing. No additional dye could be introduced to sinks in the area due to the risk of contamination of results from simultaneous traces. Barnes' results were made available to us and are summarised here. Four stream sinks were tested simultaneously, using four different dyes. Details of tracing techniques and results are presented in Barnes (1994). The sinks investigated were Black Burn sink (D28472115), Site 3 (a sink towards the south end of Tower Road, D29312255), Crearlagh Burn (D28292496) and Cushenilt Burn (D26612406). Positive traces were determined from Black Burn sink to Foaran Rising (D30062436), Crearlagh Burn to Springs 40 and 44 and Cushenilt Burn to Spring 15 (D26462489). Sink Dye used Positive tracing --------------------------------------------------------------- Black Burn Sink (Site 22) Fluorescin Foaran rising Site 3 Rhodamine none Crearlagh Sink (Site 28) Photine Spring 15 Cushenilt Sink (Site 16) DY96 Spring 40 & 44 --------------------------------------------------------------- (ii) Geology Black Burn Cave is unique in that it is the only known river cave system formed in the Ulster White Limestone Formation. Approximately 57m total thickness of this formation are exposed between Carnlough and Garron Point (Fletcher, 1977), the formation overlying the bioclastic calcareous Liassic clays, and being overlain in turn by the Antrim Basalts. The Ulster White Limestone Formation has been divided into a large number of members and the following succession has been established in the Black Burn area (Fletcher, 1977): - Antrim Basalts Clay with Flints -----------------------------------------Disconformity | Portrush Chalk Member | Garron Chalk Member Ulster | Glenarm Chalk Member White | Ballintoy Chalk Member Limestone | Larrybane Chalk Member Formation | Boheeshane Chalk Member | Creggan Chalk Member | Cloghastucan Chalk Member | Galboly Chalk Member -----------------------------------------Disconformity Lias Clay Triassic sandstones Stream sinks are at or near the contact between the Ulster White Limestone Formation and the overlying Clay with Flints, and the resurgence level is presumed to be at the contact between the Galboly Chalk Member and the Lias Clay. II - Underground Karst (i) Black Burn Cave In normal conditions the stream sinks at the base of a 25m high basalt waterfall, presumably the contact between the Antrim Basalts and the Portrush Chalk Member. The entrance to Black Burn cave lies 110m east of the waterfall and water sinks at this locality in high water conditions. During floods the cave system is too immature to allow all the water to sink at this site and Black Burn carries a stream to the coast. The current entrance to Black Burn Cave is located at D24622117. This cave has been surveyed for a total length of 142m to date but a further 350m of passage was explored in 1984 by digging through a mobile boulder choke and diving five sumped sections. Black Burn cave can be classified as an epiphreatic cave and in normal conditions the cave carries enough water to prevent entry by cavers. The passage is controlled by the major joint sets and alternates between sections of vadose and sections of perched phreatic passage. In addition to the entrance series, there are a number of avens which lie on the controlling joints and bring trickle inlets and coarse clastic sediments into the main conduit. A series of joints are seen in the north and south cliff sides at a narrowing of the gorge 80m downstream from the waterfall and low water river sink. There is a 3m vertical drop in the stream bed at this point. Access to the cave is via a number of the enlarged joints in this area. Flood debris frequently blocks these rifts, restricting access which can only be gained after digging and removing the debris (e.g. logs). Upstream of the 3m waterfall, an enlarged joint leads to a 4m climb down into a chamber. The joint is known to continue south but is currently choked. Downstream of the 3m waterfall is another prominent joint through which access to the cave was possible after digging in 1994. This joint though initially horizontal and restricted (1.5m high by 40cm wide), quickly develops into a series of short vertical rifts dropping a total of 12m into a chamber. Three other prominent avens enter the roof of this chamber, the most southerly of which leads back up to the choked joint above the 3m waterfall. In this entrance series of shafts, there are a number of large collapse boulders. From the entrance pitches the passage follows a southerly trending joint and the vadose nature of the passage changes to phreatic for 15m to a point where the joint control changes from south-southwest to the southeast. Here the passage is a fine phreatic tube with well developed scalloping and a small vadose trench. This leads to an aven chamber after 10m. It is possible to climb up from this chamber into a series of passages heading north towards the gorge. From this chamber a vadose passage with a notch at stream level follows a southerly trending joint to a point where a small inlet feeds into the main conduit. In very low water this is the first flowing water encountered in the cave. The stream leaves the main conduit 20m downstream at another change in joint control. The passage is significantly widened into a notch at floor level, particularly where basalt cobbles form the passage floor. The passage now trends northwest, maintaining proportions of 4m high by 1m wide until another aven chamber is encountered. This is the current limit of the survey, the aven being partially filled with basalt boulders which have prevented a continuation of the survey. The location of this point is close to the base of the basalt waterfall on the surface. The general direction of the unsurveyed passage is northwest and similar in characteristics to the surveyed cave. The phreatic sections during the initial exploration in 1984 held water (five sumped sections). After the first sump, the main stream enters and the passages increase in size. The vadose sections between the sumps reach a maximum of 6m by 2m, significantly larger than in the surveyed section of cave. There is also a significant loss of height in this section, including a 4m waterfall. Exploration was halted at the fourth sump (sump 5 in all) in the Main Stream Passage. (ii) Foaran Rising Foaran Rising is the source of the Foaran River, at ~70m from source to high water mark, probably the shortest river in Northern Ireland. The resurgence is located 5.57m amsl at D30062436, near Garron Point. The stream resurges from a pool some 2m by 3m at the base of a 3m high white limestone scarp and the stream bed is composed of fossiliferous Liassic clay. The rising is impenetrable. | |
| Importance: | |
Black Burn Cave and the Garron karst drainage system are the only systematically explored karst system in the Ulster White Limestone Formation. It is probably the most extensive known karst system developed in Cretaceous Limestones in the U.K. and illustrates that extensive cave development can take place in Cretaceous carbonates in the U.K. | |
| Interpretation: | |
Black Burn Cave is a significant, relatively young, epiphreatic cave with vadose inlets, developed by water from Black Burn sinking at the contact between the Cretaceous Ulster White Limestone Formation and the overlying Tertiary Basalts. Water sinking at this site resurges at Foaran Spring, 3.5km to the north-northeast. It is a highly dynamic system with changing flow systems in the entrance series related to changing sink locations. Open fissures, probably from the floor of the surface gorge, direct flow and coarse clastic material into the system. Collapse features are restricted to the initial entrance series. Horizontal passage forms are generally phreatic in nature, with vadose sections restricted to the vertical inlets. The significant floor notch development is a result of enhanced solution of the limestone above the basalt flooring, a feature termed guarding. The cave orientation is initially southwest and subsequently northwest, generally following the direction of the dominant dip of the limestone (west). It is presumed that the unexplored cave passage leading to Foaran Rising follows fractures trending approximately north-northeast. | |
| Conclusions: | |
CONCLUSION Black Burn Cave is a unique site of national, and possibly international, importance and as such warrants designation as an ASSI. This initial study shows that karstification in the Ulster White Limestone Formation is extensive, but poorly documented. Further surface and underground work is required to define the nature and extent of karstification in County Antrim. | |
| Notes: | |
For information on other karst sites in County Antrim see; Key Site 1170 - Other Karst Sites in County Antrim. For site specific information see; Key Site 434 - Red Hall Estate Key Site 435 - Tievebulliagh area Key Site 436 - Cushenilt Burn Key Site 437 - Turlough. BIOLOGICAL INTEREST Biospeleological observations and collections were initiated in the Blackburn Cave system as part of the Earth Science Conservation Review. A small faunal collection was made and identification of the specimens was undertaken by Dr. R. Anderson of the Department of Agriculture. The stream carries trogloxenes into caves and brings organic material into the system providing food for faunal populations. The cave regularly floods to the roof and the habitat is very dynamic. A ground beetle, Trechus fulvus was collected from basalt boulders on the stream bed 20m from the entrance. This species is commonly found on the upper shore around the coast of Ireland. This genus is, however, possibly partly subterranean (pers. comm. Dr. R. Anderson) and has been recorded from three caves in County Clare (Hazelton et al., 1974). It is therefore thought to maintain cavernicolous populations in Ireland (Chapman, 1993). A Collembolan, Anurida thalassophila was collected from a static pool 15m from the entrance. This species is found in coastal areas of Ireland and is probably largely subterranean as it is blind (pers. comm. Dr. R. Anderson). This Collembolan was previously unrecorded from Irish Caves. A Cranefly, Thaumastoptera calceata was collected 30m from the entrance. This common species is found around boggy springs and is almost certainly a trogloxene. In a static pool 80m from the entrance a large population of flat worms was observed grazing on the clastic sediments on the bottom of the pool and on the underside of the surface tension film. Specimens were collected and identified as Phagocata vitta which is commonly found in spring waters in Ireland. During the early exploration of the cave a number of individual pallid Brown Trout, Salmo trutta were observed in the cave and during a recent visit to the site a dead specimen was found in a dried out pool 20m from the entrance. These fish probably enter the cave by accident. | |
| Keywords | |
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| Rocks: | Basalt, Clay, Limestone |
| Structures: | joints |
| Geomorph: | cave, clastic sediments, sinkhole, sump |
| Measurements | |||||
|---|---|---|---|---|---|
| Length: | ~500 m | Width: | Height: | ||
| Depth: | Area: | ||||
| Access | |
|---|---|
| Planning: | HISTORY OF EXPLORATION A significant cave system in Carrivereagh Townland was discovered by a party of canoeists in 1984. The cave was initially explored, by Maurice Neill and Rev. George Pitt of the Reyfad Group in July 1984, for ~150m to a sump. In September 1984, Mark Campbell, Tim Fogg and Pam Fogg returned with diving gear to attempt to pass this sump. Water levels had fallen and a short duck was encountered at the sump. This was quickly passed but a sump proper was encountered after a further 40m. Beyond this, a Main Stream Passage was reached and four further sumps were passed with a further 180m of passage explored. This remains the furthest point explored in the cave. The cave was visited by Tim Fogg and John Kelly in August 1994 who discovered the old entrances hopelessly blocked by flood debris. They were able to locate a new entrance and explored a new series of pitches into the known cave. The cave was surveyed to the duck, which was discovered to have disappeared due to low water conditions. It was also discovered that a sizeable inlet to the system enters via an aven at this point and that boulders washed in via this inlet had blocked the passage making it impassable. |
| Management: | |
The entrance to Black Burn Cave lies on private land. Internal threats: Black Burn cave is an immature high energy cave with no speleothem development and no stable clastic sediment deposits. It is infrequently visited by cavers. External Threats: The cave lies above present habitation and is bounded by mature woodland. Agricultural use of land above the cave in its catchment is restricted to sheep farming and forestry. Development of large scale peat extraction or quarrying are unlikely. | |
| Threats: | Farming practices. |
| Uses | |
| Uses: | Sheep farming and forestry. |
| Potential: | The possibilities for further exploration in this cave system, and in the karst of the area, is extensive. In the cave the possibility appears to exist that there is a main collector for other sinking streams along the scarp slope, in addition to Black Burn Cave. At the furthest limits of exploration the passage dimensions are increasing. Completion of the survey to the end of the known cave is essential. A programme of dye tracing of other sinks along the eastern scarp of the Garron Plateau is planned by the authors for summer 1995. |
| References (7) | |||
|---|---|---|---|
| Barnes, S., 1994. Preliminary Hydrological Investigation of the Area between Carnlough and Waterfoot, County Antrim, Northern Ireland. (Thesis) University of East Anglia. | |||
| Campbell, M., 1984. Surprise find in Irish Chalk. Caves & Caving, numb. 26, pp.26. | |||
| Fletcher, T.P., 1977. Lithostratigraphy of the Chalk (Ulster White Limestone Formation) in Northern Ireland. Report of the Institute of Geological Sciences, vol. 77/14. | |||
| Fogg, P., 1991. County Antrim Caves & Caving, numb. 54, pp.27. | |||
| Lowe, D.J., 1992. Chalk Caves Revisited Cave Science, vol. 19 numb. 2, pp.55-58. | |||
| Savage, R.J.G., 1957. Fossiliferous fissures in the chalk of North-East Ireland. Irish Naturalists Journal, pp.147-153. | |||
| Wilson, H.E. & Manning, P.I., 1978. Geology of the Causeway coast. Memoir for one-inch geological sheet 7. Memoirs of the Geological Survey Northern Ireland, HMSO, Belfast. | |||
| Map(s): | Two areas have been outlined on OSNI 1:10,000 sheet 35; BB1. Black Burn Cave, gorge and Drumnasole townland sink. BB2. Turlough in Nappan townland, Garron Point. | ||
| Record type: | ESCR report | ||
| Entered by: | E M Porter | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Eastern Garron Plateau, County Antrim, County Antrim, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=1169. Accessed on 2026-11-06. |
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