Northern Europe has a variety of physical features including rolling hills, glaciers, and volcanoes. The region contains the British Isles and Scandinavia, with islands, peninsulas, and rugged hills and mountains that make farming difficult. Glaciers have left coastlines marked by fjords and thousands of lakes. Natural resources like oil, gas, forests, fertile soils, and fisheries have made Northern Europe wealthy. The climate is mild for the region's northern latitudes due to the North Atlantic Drift, but it varies from subarctic in the far north to mild winters in western areas.