Here's some serious thread drift. The coals are in the Mist Mountain Formation of the Jura-Cretaceous Kootenay Group.
https://www2.gov.bc.ca/gov/content/i...s/eastkootenay
Better map, cross-sections, more information and photos here:
http://cmscontent.nrs.gov.bc.ca/geos..._IC2018-06.pdf
The airfield is about 5 nm north of the town of Sparwood.