Ailsa Craig is located 16 km. off Ayrshire Coast, midway between Glasgow and Belfast, in the Firth of Clyde , an arm of the Irish Sea.
The name of the island is the anglicized form of Gaelic Aillse Creag or Creag Ealasaid which means Elizabeth's rock.
However the island is so visible and serves as a benchmark for so long in the strait between Scotland and Ireland it is mentioned in many ancient Celtic texts under various names: A ' Chreag (" the rock ") , Creag Alasdair (" the rock of Alasdair ") Ealasaid a ' Chuain (" Elizabeth of the ocean ") or Alasan .
This island, 3,200 meters in circumference, culminates at The Cairn , its top at 338 meters ... which ranks among the "marilyn" , or fell a mountain whose height exceeds 150 meters, humorous allusion to the name of the actress Marilyn Monroe.
It consists of the remains of an ancient volcanic plug , as evidenced by the basalt outcropping on its current coastline.
Volcanism is related to the opening of the North Atlantic began here about 62 million years ago, a geological episode that separated North America from Europe . Paleogene igneous intrusions , volcanoes and lava flows gave the islands that dot the western shores of Scotland ...
Skye, Mull, Rum and Ailsa Craig are leftovers. The Ardnamurchan Peninsula and basalt floods in Northern Ireland , the Giant's Causeway , were formed in the same period.