Rockall part of the deeply eroded Rockall Igneous Centre that was formed as part of the North Atlantic Igneous Province, approximately 55 million years ago, when the ancient continent of Laurasia was split apart by plate tectonics. Greenland and Europe separated and the northeast Atlantic Ocean was formed between them, eventually leaving Rockall as an isolated islet. The RV "Celtic Explorer" surveyed the Rockall Bank in 2003. The Irish Light Vessel "Granuaile" (the same name as the steamer on the RIA 1896 botany survey) was chartered by the Geological Survey of Ireland, on behalf of the Department of Communications, Marine and
Cayman Trough and extends offshore under the Pacific Ocean, where it intersects the Middle America Trench subduction zone. The relatively narrow trough trends east-northeast to west-southwest and has a maximum depth of . Within the trough is a slowly spreading north-south ridge which may be the result of an offset or gap of approximately along the main fault trace. The Cayman spreading ridge shows a long-term opening rate of The eastern section of the trough has been named the Gonâve Microplate. The Gonâve plate extends from the spreading ridge east to the island of Hispaniola. It is bounded on the north by