The geology of Alberta encompasses parts of the Canadian Rockies and thick sedimentary sequences, bearing coal, oil and natural gas, atop complex Precambrian crystalline basement rock. Geologic history, stratigraphy & tectonics The Precambrian granite and gneiss crystalline basement rocks beneath Alberta are extremely ancient, dating to the Archean and Proterozoic. The Slave Craton and Southern Alberta craton are the oldest units at more 2.5 billion years old, while younger units from the Proterozoic include the Wopmay orogeny, Great Slave Lake shear zone, Pre-Taltston basement, Taltson magmatic zone, Athabasca polymetamorphic terrane, Red Earth granulite domain, Kimiwan isotopic anomaly, Ksituan magmatic arc, Virgin River shear zone, Central Alberta intrusions and Lacombe domain. In many cases, Proterozoic deformation overprinted older Archean rocks. The Hudsonian Orogeny from 1.9 to 1.6 billion years ago was the last major regional metamorphic event. Paleozoic (539-251 million years ago) Throughout the late Precambrian and Paleozoic, a long-running marine transgression flooded western Alberta, accumulating sedimentary rocks on a basement of 1.8 billion year old Churchillian rocks. Mesozoic (251-66 million years ago) Carbonate deposition common in the Paleozoic ended during the Jurassic as the North American continent moved westward with the opening of the Atlantic Ocean. The Guichon Batholith emplaced 200 million years ago, near Ashcroft, British Columbia and was accompanied by a period of erosion that wore away Devonian, Mississippian and Triassic strata from east to west. The Late Jurassic Morrison Formation, known for its stockpiles of dinosaur bones formed as uplift in the Black Hills of western South Dakota shed sediments into Alberta. Advancing river deltas lay down the Kootenay Formation and Ferni basin in the Banff area, with offshore sands forming the Nikanassin Formation in Jasper further north. Until the Valanginian, marine conditions continued in Peace River arch and Keg River low, forming the Cretaceous Bullhead and Minnes groups. With the uplift of the Rocky Mountains, erosion accelerated in Alberta stripping away up to of the Kootenay Formation. Rivers flowing across British Columbia reversed course with debris blockage and deposited the Elk conglomerate atop the Kootenay Formation. Rivers shifted northward toward the Arctic Ocean, which transgressed southward, flooding much of Alberta in the Aptian. Fluvial coal swamps and deltas of the Blairmore and Manville groups formed along the edge of the ocean. These shorelines were important for coal and oil and gas formation. The Blairmore Group reaches up to thick, divided into the Gladstone Formation conglomerate, sandstone,