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County Antrim Karst; Cushenilt BurnAntrim
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Summary Full report
Site Type: Pothole
Site Status: PASSI
District: Larne Borough Council
Grid Reference: D267244
Rock Age: Quaternary, Cretaceous (Holocene, Santonian)
Rock Name: Ulster White Limestone Formation
Rock Type: Limestone
Other interest: No data, No Data, cave, pothole, speleothem

Summary of site:

Northern Ireland is proving to have more karst features in its Cretaceous limestone (the Ulster White Limestone, roughly equivalent to the English Chalk) than any other region of the UK. Cushenilt Burn is one example. It is one of a series of streams flowing over the imposing cliff rim of the Garron uplands, about 2km north-north-west of Knockore. Here the cliffs sweep down from around 300m to sea level in half a kilometre, providing a rugged hinterland to the coast road around Ardclinis.

The burn drains over the lava flows of the Upper Basalt Formation and cuts the prominent red strip of the Interbasaltic Bed beneath before reaching the Ulster White Limestone. There is a shaft in the limestone, now perched about 10m above the stream bed on the west bank. It is 16m deep, with a ledge at 7m, and divides into two gravel-choked shafts at its base. It appears to be the remnant of an earlier cave which became exposed as the stream progressively eroded and deepened its bed. There are small cave formations near the entrance. Work on the Cretaceous karst is in its infancy and this shaft, with a group of nearby sites, will be prominent in the research effort and should be afforded protection.

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