in Alberta used for swimming, fishing and a range of water sports. There are three large lakes, Lake Claire () in Wood Buffalo National Park, Lesser Slave Lake (), and Lake Athabasca (), which lies in both Alberta and Saskatchewan. The longest river in the province is the Athabasca River, which travels from the Columbia Icefield in the Rocky Mountains to Lake Athabasca. The largest river is the Peace River with an average flow of . The Peace River originates in the Rocky Mountains of northern British Columbia and flows through northern Alberta and into the Slave River, a tributary of the Mackenzie River. Alberta's capital city, Edmonton, is located at about the geographic centre of the province. It is the most northerly major city in Canada and serves as a gateway and hub for resource development in northern Canada. With its proximity to Canada's largest oil fields, the region has most of western Canada's oil refinery capacity. Calgary is about south of Edmonton and north of Montana, surrounded by extensive ranching country. Almost 75% of the province's population lives in the Calgary–Edmonton Corridor. The land grant policy to the railways served as a means to populate the province in its early years. Most of the northern half of the province is boreal forest, while the Rocky Mountains along the southwestern boundary are largely temperate coniferous forests of the Alberta Mountain forests and Alberta–British Columbia foothills forests. The southern quarter of the province is prairie, ranging from shortgrass prairie in the southeastern corner to mixed grass prairie in an arc to the west and north of it. The central aspen parkland region extending in a broad arc between the prairies and the forests, from Calgary, north to Edmonton, and then east to Lloydminster, contains the most fertile soil in the province and most of the population. Much of the unforested part of Alberta is given over either to grain or to dairy farming, with mixed farming more common in the north and centre, while ranching and irrigated agriculture predominate in the south. The Alberta badlands are located in southeastern Alberta, where the Red Deer River crosses the flat prairie and farmland, and features deep canyons and striking landforms. Dinosaur Provincial Park, near Brooks, showcases the badlands terrain, desert flora, and remnants from Alberta's past when dinosaurs roamed the then lush landscape. Climate Alberta extends for over from north to south;