During the last Ice Age most of Canada and the northern United States would have been covered in a sheet of ice while the American southwest would have been lush, wet, and cool. A far cry from the comparatively hot, dry, and parched land of the modern southwest. It was the warming climate at the end of the Ice Age that would alter much of the southwest but small islands of temperate climates and rich biodiversity are still present in high elevation mountain ranges and wetlands.