Paleontology and geologyDuring the Precambrian, about 1.85 Ga, several smaller pieces of land came together to form the early North American continent (Laurentia). The collisions that brought them together pushed oceanic rocks up onto the surface and created large mountain ranges. Some of these ancient continental and oceanic rocks are exposed in the northeastern corner of Alberta, while the rest form a basement below younger rocks. Alberta was near the edge of the continent, and sediments eroding off the land were deposited in shallow seas. Sandstones, conglomerates, and mudstones south of Lake Athabasca were deposited 1.7-1.6 Ma in rivers, deltas, and shallow marine environments along the coast. The sandstones and limestones deposited in the west over British Columbia, were pushed together and to the northeast as the Rocky Mountains formed. As a result, these shallow to deep marine deposits, some of which contain algal fossils, can be found in the mountains in southwestern Alberta. |