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
The Trough The Trough The Trough is a 6-mile long wooded gorge carved by the South Branch Potomac River (SBPR) and situated in the Allegheny Mountains of Hampshire and Hardy Counties, West Virginia, USA. The area was the site of a 1756 skirmish of the French and Indian War, known as the "Battle of the Trough". The steep slopes of the Trough are forested primarily with oaks, hickories, Virginia pine, large quantities of paw paw, with several rock outcrops visible on both sides. The two wooded ridges that define The Trough make it inaccessible from either side. Entry into The Trough is