Our list of the Top 20 Hard Rock and Metal Albums of 1985 shows just ... almost as if they were setting the stage for Metallica's earth-shattering Master of Puppets the following year.

Photograph by blickwinkel/Alamy Rocks themselves are made of ... Diamonds, made of carbon atoms, are the hardest natural substance found on Earth. Formed under extremely high pressure hundreds ...

The world's oldest rocks are spread across the globe and paint a picture of Earth's turbulent early history. Here are some of the most notable and important formations scientists have discovered.