A band of white intermixed high calcium limestone and dolomite at least 270 metres wide outcrops on the northeast shore of Banks Island, 8 kilometres northwest of Colby Bay, and continues inland for some distance. The band and associated chert and siltstone lie in an 8 kilometre long, northwest trending metasedimentary wedge enclosed in diorite of the Coast Plutonic Complex. The limestone bed strikes 120 degrees and dips steeply southwest. The rock is relatively free of dykes. Much of the dolomite was found to be siliceous.

Various other occurrences of white and rose coloured limestone, sometimes containing wavy lenses of diorite, are reported in this wedge of metasediments.