The Rocks Along the River

By Nick Carter

All along the Red Deer River, sedimentary layers from prehistoric times can easily be observed. The prehistoric rocks exposed along the river, carved out by thousands of years of erosion, have yielded some of the most abundant fossil remains in the world from the scenic river valleys and badlands.

Let’s mentally follow the river west to east, from its emergence out of the Rocky Mountain foothills to the Saskatchewan border. This geological tour will also take us back in time, in a sense, as the sedimentary bedrock exposed along the river tends to get older as you move east.

From just west of Sundre to about 30 km east of Red Deer, the riverside outcroppings are from the Paskapoo Formation. The rocks around here are early Palaeogene in age, which is just after the age of dinosaurs. This puts it at about 62.5 to 58.5 million years old. The Paskapoo was named by none other than Joseph Tyrrell himself, the namesake of the Royal Tyrrell Museum. Like many of central Alberta’s prehistoric environments, the ecosystem preserved in the Paskapoo was a warm, subtropical region of forests and floodplains. In addition to fossil fish, amphibians, and plants, a variety of prehistoric mammals have been found in the Paskapoo Formation, including the early primate Plesiadapis.

As it bends southward the river goes through an area where many of its tributaries pass the Scollard Formation. The Scollard spans from the end of the Cretaceous Period to the beginning of the Palaeogene, and a variety of prehistoric celebreties from the end of the time of dinosaurs like T. rex and Triceratops have been found in the Scollard.

The river itself for much of its southward run is framed by badlands made up of the Horseshoe Canyon Formation. This late Cretaceous rock, about 73 to 68 million years old, can be seen at popular destinations like Dry Island Buffalo Jump Provincial Park, Horsethief Canyon, and the Drumheller area including around the Royal Tyrrell Museum. These badlands were once a swampy coastal lowland on the edge of the prehistoric Western Interior Seaway where dinosaurs like Albertosaurus and Edmontosaurus once lived, along with many more fossil creatures.

Southeast of Drumheller the riverside exposures change to the marine Bearpaw Formation, a rock unit laid down during a time when the already-high sea levels had risen further still, covering much of eastern Alberta in seawater. Terrestrial and freshwater animal remains like dinosaurs are, unsurprisingly, rare in this formation. However, saltwater creatures like ammonites, fish, and marine reptiles like plesiosaurs and mosasaurs have been found.

Downstream from its confluence with Bullpound Creek and all the way to the Saskatchewan border, the rocks become even older, part of the Belly River group. This includes the Oldman and Dinosaur Park Formations, and the most notable outcroppings of these are found in the magnificent badlands of Dinosaur Provincial Park. This particular spot is the richest Cretaceous fossil location in all of Canada, and one of the best anywhere in the world. Aside from that, the remarkable landscape of Dinosaur Provincial Park with its rugged hillsides, alien-looking hoodoos, and arid valleys makes it worth a visit alone.

While the Red Deer River valley is rich in fascinating plants and animals, it also spoils us with its amazing scenery and hidden geological wonders. The magic of this journey back in time sparks the imagination and inspires us to dream about the vanished world hidden in the rocks along the river.