In an animation that spans tens of thousands of years, an ancient ice sheet grows to envelope land masses that would one day be known as Great Britain and Ireland. After thousands of years elapse, the ice then retreats to expose the land once more.

Known as the British-Irish ice sheet, the frozen mass began its relentless march about 33,000 years ago. Around 10,000 years later, the land was covered in ice half a mile thick. But just 5,000 years after that, the glacier had melted away, vanishing in a mere blink of geological time. Human populations that had fled a millennia-long winter re...