[3][4] Extensive outcrops of the Cairn Formation near Canmore, Alberta are a popular field trip destination for those wishing to learn about Devonian reefs.

The Cairn Formation was originally deposited as limestones and mudstones in intertidal to subtidal reef environments, and was extensively dolomitized during later diagenesis.

It now consists primarily of buff to dark grey, very fine to medium grained crystalline dolomite with good intercrystalline, biomoldic and vuggy porosity.

It occurs in outcrop in the front and main ranges of the Canadian Rockies from Kakwa Lake in northeastern British Columbia to south of the Bow River in Alberta.

[9] At reef margins the Cairn may interfinger with the Perdrix Formation which was deposited in deeper water, off-reef environments.