. Australian Garden and Field. October. 1913. THE GARDEN AND FIELD. 214 What is Soil. ? Soil is the home of the roots of the jilant. Soil is the store-house for that part of the food which the plant takes in throujf'hv its roots. Soil is the laboratory or kitchen where the food is prepared. And this work <^oes on iinceasinglv. Lastly, soil is a support to hold the plant firmly in its place. But what is soil ? Soil is finely divided rock as can "be readily seen with a microscope, clay being the finest and sand and gravel the coarsest of the divisions. In be- tween the sand and the cla}&
. Australian Garden and Field. October. 1913. THE GARDEN AND FIELD. 214 What is Soil. ? Soil is the home of the roots of the jilant. Soil is the store-house for that part of the food which the plant takes in throujf'hv its roots. Soil is the laboratory or kitchen where the food is prepared. And this work <^oes on iinceasinglv. Lastly, soil is a support to hold the plant firmly in its place. But what is soil ? Soil is finely divided rock as can "be readily seen with a microscope, clay being the finest and sand and gravel the coarsest of the divisions. In be- tween the sand and the cla}", we have what are generally known as loamy sand, sandy loam, loam, clavey loam, loamy clav and clav. These divisions are based upon the size of the soil grains and the different percentages of each size in a given soil. , They are, of course, not arbitrarily fixed, there being unnumbered variatijns of soils. N'ow if we consider soils as bro- ken and decomposed rock, the first question that comes to our mind is, how and when were the rocks which originally covered the face of the' earth converted into soil. Certainly ages and ages be- fore man appeared on the earth. In fact liefore animal life of any kind could exist there must have been vegetation ; and vegetation of the higher forms could not exist on - bare rocks. Prol)ably the commencement of the disintegra- tion was coincident with the ap- pearance of plant life in the lowest form. — In the Beginning. — (icologists tell us that the earth was once a molten mass, also that the water which now coimposes the oceans, was i)roljably in the form of a dense vapor which surrounded the red hot earth. Naturally, the earth began to cool, and it is cool- ed, it contracted. The result of this was that the surface subsided in some places and wrinkled in others, thus ])roducing the sea basins, valleys and hills. When the surface had coolf.'d sulliciently (and this cooling was hastene<l liv the vapoT in the air) the vapor conde
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