The Willow Creek Formation is a geological formation in Alberta, Canada whose strata date back to the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

. Dinosaur remains are among the fossils that have been recovered from the formation.

It was first described by George Mercer Dawson

George Mercer Dawson

Dr. George Mercer Dawson F.R.S., C.M.G., was a Canadian scientist and surveyor. He was born in Pictou, Nova Scotia, the eldest son of Sir John William Dawson, Principal of McGill University and his wife, Lady Margaret Dawson...

 in 1883 along the Willow Creek, a tributary of the Oldman River

Oldman River

The Oldman River is a river in southern Alberta, Canada. It flows roughly west to east from the Rocky Mountains, through the communities of Fort Macleod, Lethbridge, Taber, and on to Grassy Lake, where it joins with the Bow River to form the South Saskatchewan River, which eventually drains into...

. Williams and Dyer defined the type section in 1930 at the mouth of Willow Creek, east of Fort Macleod

Fort Macleod, Alberta

Fort Macleod is a town in the southwest corner of the province of Alberta, Canada. It was founded as a North-West Mounted Police barracks, and is named in honour of the North-West Mounted Police Colonel James Macleod. The town's current mayor is Shawn Patience.- History and heritage preservation...

.

Lithology

The Willow Creek Formation is composed of colored shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

 and light grey sandstones.