During the Mississippian, a flysch sequence with dark shales and graywackes was deposited. Lenses of silicic tuff exist as evidence of limited volcanism. These later sediments were formed over a subduction zone which formed along southern Laurentia.
During the Mississippian, a sequence of flysch deposits consisting of dark shales and graywackes was laid down. The existence of silicic tuff layers indicates restricted volcanic activity. These sediments were formed in an area where a subduction zone had developed along southern Laurentia.