PBS
When a Billion Years Disappeared
In some places, the rocks below the Great Unconformity are about 1.2 billion years older than those above it. This missing chapter in Earth’s history might be linked to a fracturing supercontinent, out-of-control glaciers, and maybe the...
PBS
Pbs Learning Media: The Grand Canyon: Ancient Mountains
This video segment adapted from NOVA features the twisted and melted forms of the Grand Canyon's oldest rocks, the 1.7-billion-year-old Vishnu Schist.