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 Mill Creek Mountain's ridges to rise over the South Branch. For canoeists, The Trough officially begins at the SVBR's wooden trestle at Sycamore just below where Stony Run joins the river. The Trough continues its northwestern course with several bends in the river and large boulders dislocated from the ridges above dotting its shores. The Trough passes into Hampshire County at High Knob (2,648 feet) on Mill Creek Mountain followed by a series of knobs separated by spring gaps. It is at the third spring gap where Wickham was once located at on the railroad. Following Wickham, Mill Creek Mountain's