Running water
Using so-called seismic waves, the scientists predicted that the Earth’s crust beneath our feet was made up of different types of rocks. At about a depth of three to six kilometers, the granite would turn into basalt. But the reality was very strange. The scientists were puzzled: no matter how deep they drilled, they were only able to find granite. Even at the deepest point.
The change in the seismic waves was not caused by a change from granite to basalt, as they expected. The truth was much more shocking. Several kilometers below the Earth’s crust, at depths no one expected could ever exist there, the researchers discovered flowing water.