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Ballintoy-BallycastleAntrim
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Summary Full report
Site Type: Cliff, Coastal section
Site Status: PASSI
District: Moyle District Council
Grid Reference: D045445, D120413
Rocks
Rock Age: Quaternary, Tertiary, Cretaceous (Eocene, Holocene, Palaeocene, Santonian)
Rock Name: Antrim Lava Group, Ulster White Limestone Formation
Rock Type: Basalt, Dolerite, Limestone, Tuff
Interest
Other interest: No data, Coastal processes, arch, cave, cliff, raised shoreline, shore platform, stack

Summary of site:

This 10km long area is essentially the cliff coastline, extending from a point just west of Ballintoy harbour, to the harbour in Ballycastle. The geology is relatively simple: late Cretaceous chalk (over 80 million years old) topped by early Tertiary basalt lavas (around 60 million years old). Despite this simplicity, the interaction of the cliffs with the sea has produced dramatic landforms, not least due to changes in sea level that have lifted whole shorelines beyond the reach of the present day sea.

Ballintoy harbour is small and picturesque but has a rich geology and geomorphology. The cliffs are of Cretaceous chalk, here slightly baked by the volcanic feeder now forming the Bendoo Plug (exposed on the cliff top just south of the harbour). The upper level of the cliff was previously quarried for lime, which was burnt in the massive kilns that loom over the access road. The cliff is fronted by a beach - a previous marine erosion platform now 4-5m above sea level. This beach continues west towards White Park Bay and exhibits a variety of raised beach caves, stacks and arches cut into both chalk and basalt. A short walk east from the harbour gives access to Boheeshane Bay, which has also been quarried for chalk and is backed by enormous gravity slumps. The next bay to the east is Larry Bane Bay, which can be accessed off the B15 down a road into the old chalk quarry. The cliffs along the bay are entirely of chalk and the 5m platform, though eroded, is still visible in places and marked by a line of caves, some containing large stalactites and stalagmites (suggesting a history of several thousand years). The bay terminates against the headland and island at Carrick-a-Rede (Carrickarade on the OSNI map). This truly spectacular volcanic vent was punched through the chalk and demonstrates the extreme violence of its eruptions. A combination of explosion breccias and volcanic ash drifts studded with volcanic bombs, confined on their eastern side by the ascending molten rock (now dolerite), can be fully appreciated by crossing the airy rope bridge to the island. This popular tourist destination is approached by a cliff top footpath from the same road that gives access to Larry Bane Bay. The cliffs to the east of Carrick-a-Rede are largely inaccessible (except by boat) but continue the chalk and basalt theme, although faulting has displaced the chalk below sea level in places, leaving cliffs entirely of basalt. A a path from the cliff top at Kinbane Head leads down to the castle on a shore-level promontory and again volcanic disruption, in the form of volcanic ash and shattered chalk with dolerite boulders, signals a violent past. A large natural arch north of the castle completely penetrates the Head and adds further interest. At the foot of the adjacent wooded amphitheatre of Portnakillew to the east, a small but potentially important patch of Liassic (early Jurassic) clays has been carried down in a landslip. Many dykes intersect this coast, with a larger intrusion at Gobe Feach west of Kinbane Head. Caves, waterfalls and remnants of the raised beach platform are also a feature of these sea-bound basalt cliffs that extend as far east as Ballycastle harbour. Despite the wonderful variety and number of geomorphological features that make this the finest suite of raised beaches and associated landforms in Northern Ireland, detailed research has yet to commence here. Confidant seamanship and sound methodology should yield a rich reward.


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