The Extension Colliery, owned by Canadian Collieries (Dunsmuir) Ltd., opened up in 1899. The Extension Collieries consist of four mines, all on the Wellington seam within the Extension basin. Mines Nos. 1, 2 and 3 are situated in the southwest limb of the Extension anticline and mine No. 4 (092GSW053) in the northeast limb. The Nos. 1, 2 and 3 mines are connected by the Tunnel Mine which extends about 1.6 kilometres and crosses a southwest dipping seam in the downthrown side of a main fault to the southwestward dipping seam in the upthrown side. The Wellington seam in mines Nos. 1, 2 and 3 is broken by a reverse fault of about 152 metres displacement. Mine No. 1 is situated in the northeast, downthrown side of the fault and mines No. 2 and No. 3 are in the southwest upthrown side.

The seam worked is of high volatile bituminous rank and occurs toward the base of the Upper Cretaceous Nanaimo Group, Extension- Protection Formation. The seam is interbedded with sandstone, shale and conglomerate. The floor is generally sandstone and the roof varies from shale to conglomerate.

A proximate analyses of coal from the Extension Collieries is as follows *(Geological Survey of Canada, Memoir 51, page 99):

______________________________________________________________________

Moisture Volatile Fixed Ash Sulphur Fuel Calorific

Combustible Carbon Ratio Value BTU

1.44 31.40 46.18 20.65 0.33 1.47 11401

1.52 35.27 57.04 5.85 0.32 1.61 13416

1.24 36.49 53.72 8.20 0.35 1.47 13261

1.28 35.26 55.83 7.30 0.33 1.58 13199

______________________________________________________________________

The mines were worked chiefly by pillar and stall method, almost continuously from about 1895 to 1937. The whole of the Extension Colliery was shut down and abandoned in 1937. In 1941, the No. 1 and No. 2 mines were reopened as the Deer Home Mine which produced high volatile bituminous rank coal between 1942 and 1947. In 1947, all openings to the mine were securely closed or filled by caving.

Coal was recovered from these old workings from 1947 to 1952. In 1957 the old No. 2 Mine Extension mine was reopened and coal was mined until the reserves were depleted in 1959.

J. Unsworth and A. Dunn worked the mine as the Undun No. 1 to 4 to 1967.