. Elements of farm practice, prepared especially for teaching elementary agriculture;. Agriculture. 10 ELEMENTS OF FARM PRACTICE large cracks will made by frost, tion caused by growing roots. be seen in the rocks. These cracks are by alternate expansion and contrac- heat and cooling, or by the force of When these cracks are formed little particles of rock are broken off. A strong wind will blow these particles about over the rocks, make them finer and wear off other particles. Rain and water running over the rocks do the same thing. The wind and water tend to gather the soil particles into cre
. Elements of farm practice, prepared especially for teaching elementary agriculture;. Agriculture. 10 ELEMENTS OF FARM PRACTICE large cracks will made by frost, tion caused by growing roots. be seen in the rocks. These cracks are by alternate expansion and contrac- heat and cooling, or by the force of When these cracks are formed little particles of rock are broken off. A strong wind will blow these particles about over the rocks, make them finer and wear off other particles. Rain and water running over the rocks do the same thing. The wind and water tend to gather the soil particles into crevices in the rock and other sheltered places. When several of these little particles. Figure 2.—An excellent specimen of humus". have been gathered in one place, there is the beginning of a little patch of soil. When this little patch of soil becomes moist from rain or melting snow, and the warm sun shines on it, some kind of a plant, like moss, will start to grow. At first these little patches are very small and plants can grow only a very little while. When the plants die they are added to the soil. Then other small pieces of rock are added and still other plants grow and die and are added to the little patch of soil. This has been going on for many thousands of years, so that nearly the whole surface of the earth is covered with Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Wilson, Archie Dell, 1875-; Wilson, E. W. , joint author. St. Paul, Minn. , Webb Publishing Co.
Size: 1939px × 1288px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
