A new theory to explain missing geological time, the end of leaded petrol, and the ancient humans of Arabia.

In this episode:

00:29 Unpicking the Great Unconformity

For more than 150 years, geologists have been aware of ‘missing’ layers of rock from the Earth’s geological record. Up to one billion years appear to have been erased in what’s known as the Great Unconformity. Many theories to explain this have been proposed, and now a new one suggests that the Great Unconformity may have in fact been a series of smaller events.

BBC Future: The strange race to track down a missing billion years

05:23 The era of leaded petrol is over

In July, Algeria became the final country to ban the sale of leaded petrol, meaning that the fuel is unavailable to buy legally anywhere on Earth. However despite this milestone, the toxic effects of lead petrol pollution will linger for many years to come.

Chemistry World: Leaded petrol is finally phased out worldwide

08:26 The ancient humans who lived in a wetter Arabia

While much of modern day Arabia is covered by deserts, new research suggests that hundreds of thousands of years ago conditions were much wetter for periods on the peninsula. These lusher periods may have made the area a key migratory crossroads for ancient humans.

Research Article: Groucutt et al.

News and Views: Traces of a series of human dispersals through Arabia