Dr Karl

So inside the cells it's high.

And so these pumps are always running.

So start learning about these pumps.

And once you understand that the pumps maintain the electrical balance, then you're on a good start.

And best of luck with your exam, Dr. Erin.

Well, you do have ground moving all the time.

So the classic case relates way back to Henry Thoreau who about a century and a half ago in the top right-hand corner of the USA decided he would go and think his way into clarity and went to a place called Walden Pond and built a house and then –

He realised that there were rocks that would heave themselves out of the ground and that was due to freeze-thaw cycles and they'd thaw themselves into rings and he wrote a poem called Building Wall.

I think my memory's right on that.

Maybe somebody else wrote it but it's called Building Walls and it's related to these things heaving themselves out of the ground and you're dead right.

So if you've got big temperature changes and especially ice being formed and melted, you'll get stuff heaving out of the ground.

Otherwise, you're relying on movement in the ground.

The ground is not dead solid.

You want dead solid, you put in some rock or some concrete.

But the ground will move anyway and so you can have rain and you can have just temperature cycles as well, slowly heaving stuff out.

But you're saying you find even...

A tap coming out of the ground?

Can you tell me about that?

Was that an old dump or waste tip?

There's treasures everywhere.