 DK Audio presents 13 and a half incredible things you need to know about everything, read by Alex Wingfield. What will you hear? Find out things you never knew you needed to know in this catalogue of curiosities. From bees to blood. Money to mummies. Each entry offers up 13 and a half incredible facts. Keep listening to hear where you'll go next. What did earth? Earth came into being about 4.6 billion years ago. This huge spinning ball of rock and metal is not as rigid as it seems. The surface of our planet is constantly changing as continents collide, mountains rise up and oceans widen. 1. The ground may feel firm beneath your feet, but earth's rigid outer layer, the crust, is only a few kilometres thick in places. This rocky surface makes up just 1% of earth's total volume. 2. The crust is broken into pieces called tectonic plates, which fit together like a giant jigsaw puzzle. However, unlike jigsaw pieces, these plates are constantly on the move, shifting around and crashing into each other. 3. Earth's largest layer, the mantle, is about 2,900 kilometres, 1,800 miles thick. The tectonic plates float on the mantle, which is made of solid rock but flows very slowly due to the extreme temperature and pressure. 4. Wrapped around the centre of our planet, the outer core is a liquid layer of iron and nickel. These swirling metals create earth's magnetic field. 5. Tectonic plates all move at different rates, and the Nazca plate, the plate to the west of South America, is the fastest. Every year it moves approximately 8 centimetres, 3 inches, about half as fast as hair grows. 6. Earthquakes and volcanoes often happen along plate boundaries. One such hotspot is the East African Rift, where the African plate is slowly splitting in two. Eventually, a new ocean will fill the ever-widening gap. 7. Sample complete. Ready to continue?