Dirt, of course.

And where does that come from?

Off the mountains?

Yes.  Tons on tons of white mud are being carried down past us now; and where will they go?

Into the sea?

Yes, and sink there in the still water, to make new strata at the bottom; and perhaps in them, ages hence, some one will find the bones of those sheep, and of poor Mr. Pig too, fossil—­

And the butter firkins too.  What fun to find a fossil butter firkin!

But now lift up your eyes to the jagged mountain crests, and their dark sides all laced with silver streams.  Out of every crack and cranny there aloft, the rain is bringing down dirt, and stones too, which have been split off by the winter’s frosts, deepening every little hollow, and sharpening every peak, and making the hills more jagged and steep year by year.

When the ice went away, the hills were all scraped smooth and round by the glaciers, like the flat rock upon the lawn; and ugly enough they must have looked, most like great brown buns.  But ever since then, Madam How has been scooping them out again by her water-chisel into deep glens, mighty cliffs, sharp peaks, such as you see aloft, and making the old hills beautiful once more.  Why, even the Alps in Switzerland have been carved out by frost and rain, out of some great flat.  The very peak of the Matterhorn, of which you have so often seen a picture, is but one single point left of some enormous bun of rock.  All the rest has been carved away by rain and frost; and some day the Matterhorn itself will be carved away, and its last stone topple into the glacier at its foot.  See, as we have been talking, we have got into the woods.

Oh, what beautiful woods, just like our own.

Not quite.  There are some things growing here which do not grow at home, as you will soon see.  And there are no rocks at home, either, as there are here.

How strange, to see trees growing out of rocks!  How do their roots get into the stone?

There is plenty of rich mould in the cracks for them to feed on—­

   “Health to the oak of the mountains; he trusts to the might of the
   rock-clefts. 
   Deeply he mines, and in peace feeds on the wealth of the stone.”

How many sorts of trees there are—­oak, and birch and nuts, and mountain-ash, and holly and furze, and heather.

And if you went to some of the islands in the lake up in the glen, you would find wild arbutus—­strawberry-tree, as you call it.  We will go and get some one day or other.

How long and green the grass is, even on the rocks, and the ferns, and the moss, too.  Everything seems richer here than at home.

Of course it is.  You are here in the land of perpetual spring, where frost and snow seldom, or never comes.

Oh, look at the ferns under this rock!  I must pick some.

Pick away.  I will warrant you do not pick all the sorts.