CHAPTER
1
Born in fire
Hello! I’m a kind of rock called basalt. I was born in fire!
If you saw me on this beach, you might not even notice me. For a start, there are about 100 billion pebbles along this coast, and lots are grey and speckled, just like me. Don’t be fooled by my dull appearance though – I’ve lived an amazing life. Let me tell you my remarkable story, and how I came to be here …
2
Long ago, I wasn’t solid or hard at all. I didn’t look anything like the pebble I am today. I was part of a thick soupy, molten rock that’s called magma. Magma swirls everywhere under Earth’s solid surface. It’s swirling, right now, a few kilometres beneath your feet!
the mantle - where magma swirls
the core - made up mostly of metals
I was here
thin, rocky crust
a cross-section of Earth
3
In those days, I was extremely hot – at least seven times hotter than the water that boils in a kettle. I swirled round and round, for hundreds of thousands of years. I could hear Earth’s crust moving above me. The crust’s bits are called plates. They made deafening noises as they scraped past each other, or crashed into each other. I longed to be free of all this noise and heat. I wanted to be born into the cool, fresh air.
One day, I was woken by a warning – a series of ultra-loud explosions from above. I guessed that a volcano might be forming in a gap between two of the plates in Earth’s crust. In spite of the terrible noise, I was hopeful. Could a volcano be my way out through the crust? Could I become a proper rock, cool and hard, on Earth’s surface at last?
4
The plates that make up the crust float on the mantle like rafts. Volcanoes and earthquakes often happen at the edge of plates. Mountains often form there too.
5
The problem was, things could go wrong. Sometimes magma gets trapped in part of a volcano, cools down and turns into rock there. So I could get trapped inside the volcano! Or when the volcano exploded, I might get hurled into the sky.
Some volcanoes erupt powerfully, sending rocks the size of a garden shed up into the sky.
6
Then I’d become a burning fragment, or just a handful of ash. I knew my best chance would be to spill from the crater slowly as part of a lava flow. Then I could just wait patiently to cool and harden. But I had no control over what might happen to me – I had to just wait.
Other volcanoes erupt more gently, with lava gradually pouring down their slopes.
7