The Heat-Seekers

'Doctor?' asked Sarah. 'Haven't we just emptied the Dead Sea?' Surely we've altered the course of history.'

'Not at all' the Doctor replied. 'The Dead Sea is the drain for the mighty River Jordan. We've just borrowed the water to fill the caves beneath. The Jordan will soon fill the Dead Sea once again. I suppose you can say we've just parted the waters. Now, I remember the first time that was done. In the Red Sea, by Moses...'