Step into the world of primitive technology as two skilled builders create an impressive underground dwelling from scratch. Watch as they expertly excavate the earth, shape a spacious courtyard, and ...

For years, the oldest widely accepted cave art came from Spain, where mineral crusts dated paintings to more than 64,000 years. That work also relied on uranium decay in crusts, so it offered a ...

The covalent radius (a measure of how large individual atoms are) shows different trends if you are moving across a period or down a group. A comparison of the relative covalent radii of atoms is ...