Regional maps of the Albian Peace River and lower Shaftesbury formations on the Peace River Arch, northwestern Alberta and northeastern British Columbia

Regional isopach maps of the Albian Peace River Formation and lower Shaftesbury Formation in northeastern British Columbia and northwestern Alberta indicate that the penecontemporaneously subsiding Peace River Arch affected sedimentation and erosional patterns of the mapped units. The Cadotte and Paddy members are characterized by abrupt superposed and thick northern depositional edges representing paleoshorelines that trended northeast-southwest. An elongate east-west, isopach depression in the Cadotte Member across Twps. 69, 70 and 71 is interpreted as representing an incised valley, resulting from erosion of previously deposited sediments of the Cadotte Member. In the southeast part of the map area, the Cadotte Member appears to have been erosionally removed. Superposition of modern drainage networks on the paleo-drainage network shows remarkable coincidence, suggesting an underlying structural control.