The main (or No. 1) Wellington Seam was mined at the East Wellington Colliery No. 2 Shaft, No. 1 Shaft, the East Wellington mine, and the Jingle Pot (No. 1 East Wellington mine) in order from northwest to southeast along the strike of the coal seam. The mines are separated by faulted strata or areas where the seam thins to unprofitable thicknesses. The seam occurs within the Early Campanian Northfield Member of the Upper Cretaceous Extension Formation (Nanaimo Group). Thicknesses of the seam are extremely variable within the mines mainly due to faults, folds, and other roof undulations. Quality of the seam is variable, ranging from clean coal with few shale partings to carbonaceous shale. The coal is high volatile bituminous in rank. The floor of the seam is sandstone while the roof ranges from sandstone to shale and shaly sandstone. Refer to the Bebans mine (092GSW026) for a detailed description of the Wellington Seam and the Nanaimo Coalfield operations.

The strata strike northwest and dip towards the northeast (approximately 10 degrees). To the south and west the beds are cut off by a northwest-southeast trending normal(?) fault and a number of gentle broad northwest trending folds occur in the coal bearing formation to the north and east.