The southwest corner of Greenland is a barren place. Most of the time, the only living things you can see are moss and lichen. Occasionally though, you might also spot a few scientists, who have come to study the rocks of this desolate landscape, which happen to be among the oldest on Earth. They were created around 3.7 billion years ago, when our 4.5-billion-year-old planet was still in its childhood.