Earth’s ice is expansive. In fact, 10 percent of the planet’s land mass is covered in ice—like glaciers, ice caps and ice sheets—spanning more than 5 million square miles.
As snowfalls accumulate, melt and refreeze, layer upon layer of dense snow compresses to form ice sheets and glaciers. That ice has played a huge role in our planet’s history, for hundreds and thousands of years shaping the very landscapes we know today.