AbstractCretaceous rocks extend through the mid-continent from northern Yukon Territory and District of Mackenzie southward along Mackenzie and Rocky Mountains and eastward across the Plains of Alberta, Saskatchewan, and Manitoba to the Canadian Shield. They underlie Mackenzie Delta and Plains in the District of Mackenzie. Exposures of Cretaceous rocks are found in the southern Plains along many of the major river systems. One of the celebrated localities is at Dinosaur Park, southeastern Alberta, designated a World Heritage Site. Elsewhere in the Plains, Cretaceous rocks are mainly covered by Pleistocene drift, except in the Cypress Hills and along the Manitoba Escarpment on the eastern side of the basin.Many investigations of Cretaceous rocks have been carried out over a period of more than 125 years. Studies of oil sands, heavy oil areas, and coal-bearing areas, regional and economic studies, and detailed surface and subsurface studies have contributed to understanding the history of these rocks. More than 100 000 boreholes have been drilled in the southern part of the Western Canada Basin. Well control is relatively sparse in the District of Mackenzie where, too, outcrops are lacking in large areas. Drilling in the Eagle Plains, Mackenzie Delta, and along the Mackenzie Valley has provided much needed data. Recent coal exploration in the foothills and mountains of British Columbia and in the Plains of Alberta and Saskatchewan has contributed greatly to the overall knowledge of the Cretaceous rocks.