The Mount Beirnes Cirque coal occurrence is in the Groundhog coalfield in the Bowser Basin and was identified, trenched and sampled by Dawson and Ryan in 1990 (Geological Survey of Canada Open File 2555). The location is on an unnamed alpine ridge about 8 kilometres due south of Mount Gunanoot in the Bowser Basin approximately 139 kilometres north-northeast of the community of Stewart. The Mount Klappan developed prospects (104H 020, 21, 22) are located 23 kilometres north.

The Mount Beirnes Cirque coal occurrences are hosted by the Lower Cretaceous Groundhog-Gunanoot assemblage of the Upper Jurassic-Lower Cretaceous Bowser Lake Group (Geological Survey of Canada Bulletin 577). The strata is tightly folded into closely-spaced anticline-syncline pairs; fold axes strike about 315 degrees. The occurrences are on the west flank of the Beirnes synclinorium.

Vitrinite reflectance values range from 2.53 to 2.94 per cent RoMax; rank is semi-anthracite.Coal seams range in thickness from 0.9 to 1.5 metres.