sands of hills and mountains is large. Here we see a mighty force and a powerful agent at work in soil making.

The sorting power of water.-In this connection we should not forget the work of water as it moves silt, clay, pebbles, and stone that have been caught in its channels and then moved downward toward its emptyings. Silt and clay are readily held in suspension even if the water is slow going. It requires rapid currents to move the heavier, coarser stones and pebbles. As these are carried along, their rough edges are worn off, their sides are scraped and scratched, and many particles are pulverized and ground-all contributing to soil making. To be sure, this soil will be deposited in lower regions, yet it is now soil, the same as that in the cultivated field or garden.

The rôle that ice has played. In the northern part of the United States we have a class of soils formed by giant masses of ice called glaciers, that moved in a southward course many, many centuries ago. Our ideas of the cause of this vast body of moving ice are not clear and we have only the evidence that once it was so. We are told that all the northern part of our country was covered with a frozen mass of ice and snow, and that for some reason this whole mass assumed a moving character, creeping over plain and stream, attacking every hill top and mountain range, and without further ado, conquering them as if play mounds made by children's hands were the confronting power.

As this huge mass moved onward in its course it gathered up huge rocks that once were free, quarried other giants from the bosoms of the mountains, and played with them as it went along-rolling them, forcing them together, dragging them, rubbing their rough faces until they were smooth (if perchance they were not completely ground into powder)-until finally the rays of the

more southern sun robbed the glacier of its power by melting snow and ice, which freed, rushed on into river channels to be lost at last in the seas of the East and the South.

Soils that were formed by this moving mass of ice are known as drift soils. Such soils vary greatly in composition and in physical nature. The area formed by these glacier or drift soils is altogether lacking in uniformity, its surface is broken often abrupt, its elevation is sometimes considerable, often but slight and its producing power is modified by the nature of the deposits. While it is true that these soils are fairly well supplied with necessary mineral constituents essential to plant growth

they are often deficient in organic matter-the source of nitrogen supply.

Wind made soils.-While the wind is often most vigorous in its activity, it is a reasonably slow agent in soil making, when considered by its daily work; it must be studied only in its aggregate in respect to all the geolog

ical ages past. You will find the wind most actively at work in arid regions and in those sections where sand and dust most abound.

A single experience in a wind storm must convince you of the power as well as of the quantity of earth that is moved throughout the world. Dust or particles of the earth are in the air at all times, and with every drop of rain, every flake of snow, and every movement in the air these particles are carried elsewhere than to the spot at which they were originally gathered up. You will find in some sections of our country huge mounds or drifts of sand that have been deposited by the constant and more vigorous action of the wind.

CHAPTER II

THE SOILS THAT LIVING THINGS HAVE MADE

No one knows just when the first plant came into the world, nor the kind: it was too far back in the dim ages of the past; long before any history was ever written; long even before man or bird or beast had yet appeared. We may be sure, however, that it was a very tiny plant, so small that the little roots did not need to go deep into the earth, for the soil was just beginning its growth. We may be safe even in saying that these early forms of plants had only the rock itself for their homes, and on this rock they established themselves, sending their small roots just the tiniest bit into the crevices and into the opened particles that had been loosed by air and water, by heat and cold.

The beginning of plant growth.-But doubtless the earliest forms of plant life were aquatic in character: they lived in the water. We have learned of the solvent power of water. Many of the early stagnant pools became depositories of water holding in solution the dissolved mineral materials of the kind forming the rock structures. This was just the sort of food that these pioneer plants fancied, for they and all of their kind since have secured their feeding materials in this manner. As years and centuries passed, these beginning forms of plant life became stronger, more steady and some became quite venturesome, clinging to the rocks that held fast the waters of the pool; and still others, flinging the experience of their parental tribes to the winds, ascended beyond the limits

of the pond, where flowing water was uncommon, there to become adjusted to their new homes and to their new environment-at last to be stationary in their rules of living.

It is likely the first stationary forms found lodgment in the crevices of the rock, where perhaps had accumulated small quantities of soil that had been made long before by air and water working in unison. These plants, no doubt, set their fibrous roots firmly against the rock surfaces and worked in their own way in securing the coveted elements locked in the storehouse of the rocks.

Just as the ivy of to-day creeps over stone and brick, so did these first forms secure their food substances for their life and growth. But with this difference: those were small, insignificant plants and of low order; the ivy has culture, good breeding and pedigree as its inheritance. Real soil was made and left.-You must not think