Beyond this imaginary line, no trees can grow. It's just too cold, they cannot survive. It is home to the world's biggest concentration of free-roaming large mammals. These are Barren-ground Caribou, the so-called "Buffalo of the Tundra." They began their annual migration cycle through this area soon after the last ice age ended. Evidence of that age is still plainly visible in the glacial etchings and deposits found throughout the region
