1. 'I should like to see a rock all made of slate! Have you ever seen one, mother?'

'Yes, many, dear. But there are none near.' Then she laughed a little. 'But if you like to go just outside the door you will see rows and rows of slates.'

2. Out they ran, looked all over the ground, then at the garden-wall, then back at their mother, who had come to the door.

'Look at the house,' she said, 'look higher!'

3. 'Oh, we never thought of the roof,' they cried, and ran in again laughing. 'But those slates are not so nice and smooth as our slates.'

'Your slates are made smooth on purpose. Besides, they are made of better slate—older slate. The older the slate is the better it is.'

4. 'How old?'

'No one knows. It is a long story, and no one can tell it properly. Shall I tell you as much as I know?'

'Yes, do, please, mother!' and the two settled themselves at her feet.

5. 'Well,' she began, 'once upon a time there was a great stir at the bottom of the sea. The heat and gas under the ground broke through and pushed out everything that was in the way.

6. 'Stones, ashes, and dust came flying up through the water, and then fell back into the water again. When all was quiet, they settled down at the bottom of the sea, and became mud.

7. 'All this happened many times, till there was a great deal of mud. Then, little by little, the mud was covered up by other things.'

8. 'What sort of things?'

'Dead fish, perhaps, and shells, and sand and mud that had been brought by rivers into the sea. These things lay on the top of the mud and weighed it down.

9. 'The heat under the bottom of the sea still kept up, and made the mud very hot, and baked it through. At last it gave a great push, and heaved the mud up above the water, so that it became dry land.

10. 'In other ways it was made harder and harder, until it was turned into rock. And now we call it slate. Here is a bit of your old broken slate. See if you can turn it into mud again!'