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 or near the islet. Cold-water coral biogenic reefs have been identified on the wider Rockall Bank, which are contributing features for the East Rockall Bank and North-West Rockall Bank SACs. In December 2013 surveys by Marine Scotland discovered four new species of animals in the sea around Rockall. These are believed to live in an area where hydrocarbons are released from the sea bed, known as a cold seep. The discovery has raised the issue of restricting some forms of fishery to protect the sea bed. The species are: The earliest recorded date of landing on the island is