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
Brent Spar to this search: firstly, that the site was within the UK exclusive economic zone, and secondly, that the site be deep enough that the sunken buoy would present no hazard to shipping. FRS identified three sites as squares, which were considered suitable; the Maury Channel, the North Feni Ridge and the Rockall Trough. At these three sites, FRS carried out: The North Feni Ridge was found to include a narrow channel. The Rockall Trough area was found to be a gently sloping basin between the Anton Dohrn Seamount and the Wyville-Thomsom Ridge. The Maury Channel area was found to be