Courtesy of the Northern Pacific Railway
ASTER GROWING IN VOLCANIC ASH ON MT. RANIER
[THE GREAT PLOUGHS OF THE ICE AGES]
With all the work the other agencies do in changing the rock into soil, and fertilizing and refreshing it with additions from the subsoil, there still remains an important thing to be done, and that is to mix the soil from different kinds of rock. This is still done constantly by the winds and flowing waters, but every so often, apparently, there needs to be a deeper, wider stirring and mixing. This the great ice ploughs and glacial rivers of the Ice Ages did. And they do it every so often, probably; for there was more than one Ice Age in the past, and, as Nature's processes do not change, it is more than likely there will be more ice ages and more deep ploughing and redistribution of the soil in the future. As you will see, if you take the trouble to look it up in "The Strange Adventures of a Pebble," it is thought we may now be in the springtime of one of those vaster changes which bring Springs lasting for ages, followed by long Summers and Autumns, and by the age-long Winters and the big glaciers and all.
HOW THE MOUNTAINS FEED THE PLAINS
"The elevations of the earth's surface provide for it a perpetual renovation. The higher mountains suffer their summits to be broken into fragments and to be cast down in sheets of massy rock, full of every substance necessary for the nourishment of plants, and each filtering thread of summer rain is bearing its own appointed burden of earth to be thrown down on the dingles below."
The glaciers, moving over thousands of miles and often meeting and dumping their loads together on vast fields, did the very same thing for everybody that England does for herself to-day in bringing different kinds of fertilizers from all over the world to enrich her farms. I'm very glad to speak of this because the author of the story of the pebble may have left a bad impression of the glaciers—"The Old Men of the Mountain"—as farmers, by what he said about their carrying off the original farm lands of New England, and leaving a lot of pebbles and boulders instead. While these pebbles have not produced what you would call a brilliant performer among soils, they have made a good, steady soil that in New England has helped greatly in growing farm boys into famous men, while the pebbles of Wisconsin have been of immense service to her famous cows. In the counties in Wisconsin where there are plenty of pebbles scattered through the soil, the production of cheese and butter is something like 50 per cent greater than it is in regions where there are comparatively few pebbles.[35]