The Coal Swamps
Saskatchewan has the most complete Tertiary Period fossil record in Canada. The coal deposits left behind by the swamps in southern Saskatchewan contain a great deal about the species that roamed the land after the great Cretaceous extinction. Fish, crocodiles, turtles, salamanders, lizards and a variety of mammals were among the survivors. The fossils show that mammals diversified very quickly at about the time of the demise of the dinosaurs.
The Late Eocene - The Great Plains Take Shape
Thousands of fossils found at the Calf Creek site, Northwest of Eastend, tell a story from approximately 36 million years ago, a time when the landscape began to take its modern shape. The prairies started to experience seasons as the climate cooled, causing the dense semi-tropical forests to change into large open plains with patches of woodland. Mammals were evolving too. Rhinoceros-like brontotheres, three-toed horses roughly the size of large dogs, small deer-like grazers and even sabre-toothed cats appeared.
The Miocene - Life on the Grassy Savannah
Fossils found in the Wood Mountain region indicate that the landscape was dominated by grassy plains with small areas of woodland, possibly along stream banks. The largest numbers of small mammal fossils are of pocket mice, which prefer to live in an open grassy environment. There had to be some sparse forest as well as fossilized wood was found there as were fossils of animals that require trees for food and habitat, like flying squirrels and hedgehogs. Although mastodonts were common during the Miocene, the most numerous large mammals were the three-toed horse Merychippus and the pronghorn, Merycodus.
Buried by Ice - The Advance and Retreat of the Glaciers
Beginning 2 million years ago, the Pleistocene Epoch - also known as the Ice Age - was the most recent major event in Saskatchewan's geological history.
Five great sheets of ice covered most of the province. The Wood Mountain region and the Cypress Hills in southwest Saskatchewan were both tall enough not to be covered by the ice sheets.
Nearly all of the landforms that we see in Saskatchewan were shaped by the advance and retreat of the last glaciation. Scientists are unsure what caused the cooling effect that brought about the Ice Age, but they do know how the ice sheets were formed. Thick layers of snow that fell in winter did not completely melt in the summer because of the cooler temperatures, causing a layer of ice to form that became thicker and larger as the years passed.