43K views · 1.2K reactions | We tend to think of Earth's land as being fixed in place, but in reality, it's constantly moving on tectonic plates. As landmasses move, geologic "scars" occur that can be mapped and exposed. One such scar beneath Greenland has helped sharpen our understanding of the dynamics that dominate and shape terrestrial planets. Details: https://go.nasa.gov/2OFsFcq | NASA Earth | Facebook