Eolian coastal dune deposits and surrounding marine sandstones, Rocky Mountain Supergroup (Lower Pennsylvanian), southeastern British Columbia
The Pennsylvanian Rocky Mountain Supergroup, in the Elk Range, B.C., includes three sandstone formations: Tyrwhitt (about 100 m thick), Storelk (about 95 m), and Tobermory (about 75). The Tyrwhitt consists mostly of structureless sandstones which prove to be bioturbated in X radiographs. There is an abundant trace fauna, as well as brachiopods. The second most abundant facies consists of medium scale (up to about 1 m) cross-bedded sandstones. The Tobermory is essentially similar to the Tyrwhitt but contains fewer structureless sandstones, and more beds with ripple cross-lamination and horizontal lamination. Both formations were probably deposited slowly in water deeper than fair-weather wave base (deeper than 10–15 m).The Storelk, sandwiched between Tyrwhitt and Tobermory, is dominated by large scale (up to 10.5 m) sets of cross-bedding. These occur in three members, separated by two structureless members. The Storelk structureless members are not mottled in X radiographs, and no trace fauna was found in ...