| Site Type: | Karst | | Site Status: | local interest | | Council area: | Causeway Coast & Glens Borough Council | | Grid Reference: | J450954,D193263,D267244,D29282243 | | Bing maps: | 54.78596,-5.74601 | | Google maps: | 54.78596,-5.74601 | | Rocks |
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| Rock Age: | Quaternary, Tertiary, Cretaceous (Eocene, Holocene, Palaeocene, Santonian) | | Rock Name: | Antrim Lava Group, Lower Basalt Formation, Ulster White Limestone Formation | | Rock Type: | Basalt, Flint, Laterite, Limestone | | Interest |
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| Other interest: | cave, doline, pothole, sinkhole, speleothem, turlough |
| Summary of site: |
| The karst of the Cretaceous Ulster White Limestone has been one of the most interesting discoveries of recent time. Black Burn Cave is the finest cave yet discovered, while sites at Red Hall, Tievebulliagh and Cushenilt Burn are also worthy of note (see site descriptions). | | Other sites have yet to be fully investigated, including a stream sink hole north of Ballycarry Village, a 22m deep shaft on the bank of the Ardclinis Burn and what appears to be a turlough (a small lough filling and draining through joints into its limestone bed). There are also interesting examples of fossil karst features, i.e. features from an earlier period preserved in the rocks. There was a time, at the end of the Cretaceous period and before the onset of Tertiary volcanic activity, when the newly consolidated Ulster White Limestone was elevated above sea level and formed the land surface. Acidic rain, falling on to pure limestone, created extensive karst landscapes. Where evidence can be seen in cliffs (particularly around the Antrim coast), the surface of the limestone beneath the basalts that eventually buried them is very irregular, indicating valleys and what appear to be karst pinnacles with weathered flints lying in lateritic muds and silts in the hollows. This is exactly what would be expected, the flints having weathered out of the limestone and settled into the soils in valleys and depressions. | | Larger karst features might also be expected and so far two have been found: | | 1. A large conical depression can be seen in the White Limestone in the cliff above Fallowvee, filled with horizontal layers of laterite incorporating weathered flints. It is interpreted as a collapse structure (a doline) that became choked with flinty soil deposits. | | 2. There is also a feature within the White Limestone on the eastern bank of Cushenilt Burn with an oval cross section about 3m wide by 1.5m high. It is a cavity, again filled with red silty muds with flints, and shows all indications of being a phreatic (i.e. formed below the water table) cave passage that became blocked with muddy soil when it eventually linked to ground surface. | | Both these late Cretaceous/earliest Palaeocene karst features were sealed beneath the lavas of the Lower Basalt Formation, thus preserving a tantalising glimpse of the landscape and processes of that time. | | A great deal of research remains to be performed into the recent and ancient karst of the Ulster White Limestone, and it seems likely that more sites await discovery. |
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