A largely fault bounded belt of limestone with minor dolomite, shale, siltstone and sandstone of the Hadrynian Cunningham Formation, Cariboo Group, extends northwest from Mt. Amos Bowman to Wolverine Mountain along the east side of Isaac Lake for 28 kilometres. The belt varies up to 3 kilometres wide. Various exposures of overlying chloritic schist, phyllite and quartzite of the Yankee Belle Formation lie within the belt. Bedding generally strikes northwest and dips between 25 and 40 degrees southwest.

The limestone consists of bedded to massive micrite and calcarenite with oolites, pellets and algal grains. The dolomite is commonly silty and sandy. Rounded quartz granules are sometimes contained in the dolomite.