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
Island of Rockall Act 1972 Majesty on 18th September 1955 in pursuance of a Royal Warrant dated 14th September 1955 addressed to the Captain of Her Majesty's Ship Vidal) shall be incorporated into that part of the United Kingdom known as Scotland and shall form part of the District of Harris in the County of Inverness, and the law of Scotland shall apply accordingly." It was amended by the Local Government (Scotland) Act 1973 to transfer administrative control to the Western Isles Council when Inverness-shire was abolished. Island of Rockall Act 1972 The Island of Rockall Act 1972 (c. 2) is a British Act of