Upper Cretaceous Haslam Formation shale of the Nanaimo Group is exposed in a quarry and along the Koksilah River for several hundred metres. The shale consists of dark grey to black crumbly rock in 6 to 13 centimetre beds. The beds strike 110 degrees and dip steeply north. Fossils are abundant in some horizons.

In June 1969, the quarry was 120 metres long, 40 metres wide and 7.5 metres deep. The shale is trucked to a plant in Bamberton for use as a light-weight aggregate in the making of concrete. The same shale was used in 1947 for the manufacturing of dry-press brick. No production figures are available.