So you must read of them in such books as Peaks, Passes, and Glaciers, and Mr. Willes’s Wanderings in the High Alps, and Professor Tyndall’s different works; or you must look at them (as I just now said) in photographs or in pictures.  But when you do that, or when you see a glacier for yourself, you must bear in mind what a glacier means—­that it is a river of ice, fed by a lake of snow.  The lake from which it springs is the eternal snow-field which stretches for miles and miles along the mountain tops, fed continually by fresh snow-storms falling from the sky.  That snow slides off into the valleys hour by hour, and as it rushes down is ground and pounded, and thawed and frozen again into a sticky paste of ice, which flows slowly but surely till it reaches the warm valley at the mountain foot, and there melts bit by bit.  The long black lines which you see winding along the white and green ice of the glacier are the stones which have fallen from the cliffs above.  They will be dropped at the end of the glacier, and mixed with silt and sand and other stones which have come down inside the glacier itself, and piled up in the field in great mounds, which are called moraines, such as you may see and walk on in Scotland many a time, though you might never guess what they are.

The river which runs out at the glacier foot is, you must remember, all foul and milky with the finest mud; and that mud is the grinding of the rocks over which the glacier has been crawling down, and scraping them as it scraped my bit of stone with pebbles and with sand.  And this is the alphabet, which, if you learn by heart, you will learn to understand how Madam How uses her great ice-plough to plough down her old mountains, and spread the stuff of them about the valleys to make rich straths of fertile soil.  Nay, so immensely strong, because immensely heavy, is the share of this her great ice-plough, that some will tell you (and it is not for me to say that they are wrong) that with it she has ploughed out all the mountain lakes in Europe and in North America; that such lakes, for instance, as Ullswater or Windermere have been scooped clean out of the solid rock by ice which came down these glaciers in old times.  And be sure of this, that next to Madam How’s steam-pump and her rain-spade, her great ice-plough has had, and has still, the most to do with making the ground on which we live.

Do I mean that there were ever glaciers here?  No, I do not.  There have been glaciers in Scotland in plenty.  And if any Scotch boy shall read this book, it will tell him presently how to find the marks of them far and wide over his native land.  But as you, my child, care most about this country in which you live, I will show you in any gravel-pit, or hollow lane upon the moor, the marks, not of a glacier, which is an ice-river, but of a whole sea of ice.