Madam How has more than one string to her bow, or two strings either; so when she pours out her lavas, she does not always pour them out in the open air.

Sometimes she pours them out at the bottom of the sea, as she did in the north of Ireland and the south-west of Scotland, when she made the Giant's Causeway, and Fingal's Cave in Staffa too, at the bottom of the old chalk ocean, ages and ages since.

Sometimes she squirts them out between the layers of rock, or into cracks which the earthquakes have made, in what are called trap dykes, of which there are plenty to be seen in Scotland, and in Wales likewise.

And then she lifts the earth up from the bottom of the sea, and sets the rain to wash away all the soft rocks, till the hard lava stands out in great hills upon the surface of the ground.

Then the rain begins eating away those lava-hills likewise, and manuring the earth with them; and wherever those lava-hills stand up, whether great or small, there is pretty sure to be rich land around them.
If you look at the Geological Map of England and Ireland, and the red spots upon it, which will show you where those old lavas are, you will see how much of them there is in England, at the Lizard Point in Cornwall, and how much more in Scotland and the north of Ireland.