The Earth is not a solid mass of rock: its hot, dark, fractured subsurface is home to weird and wonderful life forms

The living landscape all around us is just a thin veneer atop the vast, little-understood bulk of the Earth’s interior. A widespread misconception about the deep subsurface is that this realm consists of a continuous mass of uniform compressed solid rock. Few are aware that this mass of rock is heavily fractured, and water runs in many of these fractures and faults, down to depths of many kilometres. The deep Earth supports an entire biosphere, largely cut off from the surface world, and is still only beginning to be explored and understood.