Under Greenland’s Ice Sheet

Greenland is Earth’s largest island, and most of it is covered by ice up to 2 miles thick. Scientists decided to investigate the age of this ice sheet and were surprised to find that not that long ago, there wasn’t one. They used ice cores to date different areas, then flew planes over it with special ice-penetrating radar. The radar identified bands of softer and harder ice and layers within them, which they matched to the ice cores to determine different ages of ice across the island. Turns out Greenland’s ice accumulated in three separate events: the oldest beginning 130,000 years ago; the middle one during the last Ice Age; and the most recent just 12,000 years ago. Equally interesting, the radar revealed the bedrock beneath the ice sheet to find that a giant rift as deep as the Grand Canyon and even longer, at almost 500 miles, splits the island and exits north into the Arctic Sea. It’s possible this was formed by massive floods as much as 2 million years ago. They also found a huge impact crater that appears to have been made by a mile-wide meteorite, which might be the one that caused the lingering Ice Age discussed in a previous episode. It’s unclear when it struck Earth, but it was at least 12,000 years ago, since the young ice above it is undisturbed. This new technology has given us a remarkable first look at Greenland’s landscape, otherwise hidden beneath the ice.