[3] It is present throughout much of the central Alberta plains, where it is an important stratigraphic marker in the nonmarine Upper Cretaceous sequence.
A marker bed called the Kneehills Tuff is present in the upper part of the formation.
[4] It consists of distinctive mauve-grey to purplish brown mudstones with minor siltstone and rare sandstone.
The mudstones contain a large component of volcanic ash that has been altered to bentonitic and montmorillonitic clay, and they form a porous, popcorn-like crust upon weathering.
[4] It is poorly fossiliferous, but arthropods including insects and arachnids preserved in amber,[7] spores, bone fragments, algal remains and carbonized wood have been reported.