Benue Trough the Central African Shear Zone and for the volcanic island of St. Helena in the Atlantic ocean. Three periods of magmatic activity (volcanic action) have been identified, 147–106 Ma, 97–81 Ma and 68–49 Ma. The first is prominent in the north of the trough, and contemporary with magmatism in Brazil, probably occurring during a period of crustal extension before the Atlantic started to open. The second is found only in the south of the trough, and may belong to a period when the extension of the Atlantic had slowed down, ending with a period of compression. The third and last
Rockall on its proximity to the Irish mainland, however the country has never formally claimed sovereignty over the rock. Although Rockall is closer to the UK coast than to the Irish coast, Ireland does not recognise the UK's territorial claim to Rockall, "which would be the basis for a claim to a 12-mile territorial sea". Ireland regards Rockall as irrelevant when determining the boundaries of the Exclusive Economic Zones (EEZ) as the rock is uninhabitable and in signing the United Nations Convention on the Law of the Sea (UNCLOS) in 1997, the UK has agreed that "Rocks which cannot sustain human