The Comox Formation is overlain by marine shales and the Upper Cretaceous Extension and Protection Formations, which contain three mineable seams. These formations outcrop in the area around the city of Nanaimo and define the Nanaimo Coalfield, which covers about 1300 square kilometres. Coal seams are broken by numerous of normal faults, which disrupt an easterly regional dip. In the hundred years preceding 1953, more than 50 million tonnes of high-volatile A and B bituminous coal were produced from this field. The coal was sold mainly as a thermal coal, though some was used to make coke on the Island. The producing area, in which the Douglas, Newcastle, and Wellington seams were mined, covered about 170 square kilometers.
BC Geological Survey
British Columbia Ministry of Energy and Mines
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