South Africa
Sand Origin
Waterval, Rustenburg
Random Sand Fact
Can sand reveal how long a day was 3.2 billion years ago?
In South Africa, some of Earth’s oldest preserved tidal deposits remain. Sand once moved back and forth by the tides has become sandstone, but the rhythm between the layers is still there.
By reading that pattern, researchers have estimated that a day may then have lasted around 13 hours and that the Moon was considerably closer to Earth than it is today.
