The mountain group is trotting along the track again. Tommy Tompson continues his geological theme. 'You know a huge chunk of this mountain has been worn down in the last few million years. Where we're walking now used to be deep underground.'

'Oh,' says Fuzzy, who is rapidly losing interest.

'Yep. Millions of years ago the whole of Tasmania was covered with a great slab of sedimentary rock that once had been at the bottom of the sea. Then an igneous intrusion--like magma from an underground volcano--leaked out under the soft sedimentary rock.'

'An underground volcano???' says Fuzzy.

'Well, sort of. The magma can't explode into the air because it's buried so deep. So it oozes out in humongous slabs then slowly cools off.'

Fuzzy knows what to expect next. She says, 'Millions of years later...'

Tommy continues... 'Millions of years later all the streams that trickle over the mountain have finally worn away all the soft rock, leaving the hard rock underneath. That's what we're walking on now.'

'Oh,' says Fuzzy as she tries to blow her nose on a sodden tissue.