The Morrissey Formation is a stratigraphic unit of Late Jurassic (Portlandian) age in the Western Canada Sedimentary Basin.

They were deposited along the edge of the Western Interior Seaway in extensive littoral, deltaic and beach environments.

Thin beds of carbonaceous mudstone and coal near the top of the formation may have been deposited in interdune, lacustrine or swale environments.

Several genera of molluscs (e.g., Oxytoma, Modiolus, and possibly Pachyteuthis) have been collected from the Weary Ridge Member.

A single impression and a few fragments of the ammonite Titanites occidentalis, which have been recovered from the top of the Moose Mountain Member, indicate a Late Jurassic (Portlandian) age.