. Elementary agriculture with practical arithmetic. Agriculture. 3,2 ELEMENTARY AGRICULTURE SO hard is that only the hard ones could withstand the grinding'. The softer ones were easily ground up and formed soil. In the western part of the state of Wisconsin, in eastern Iowa, and in northern Illinois is a tract known as the "driftless area," over which the glacier did not pass. Here the soil may be seen in the actual process of formation. The rock on top grad-. Drawing. showing how rock gradually breaks up and de- cays from the top downward. Drawing, showing glacial drift deposited o
. Elementary agriculture with practical arithmetic. Agriculture. 3,2 ELEMENTARY AGRICULTURE SO hard is that only the hard ones could withstand the grinding'. The softer ones were easily ground up and formed soil. In the western part of the state of Wisconsin, in eastern Iowa, and in northern Illinois is a tract known as the "driftless area," over which the glacier did not pass. Here the soil may be seen in the actual process of formation. The rock on top grad-. Drawing. showing how rock gradually breaks up and de- cays from the top downward. Drawing, showing glacial drift deposited on top of the solid rock. ually "rots" and breaks up. The water washes the lighter portions down and spreads them out at lower levels. The rain and snow work their way into the cracks of the rocks and, freezing there, break them up into smaller pieces. Even the wind breaks off small pieces and carries them away. Great drifts of sand, like snow, may sometimes be seen piled up by the action of the wind. Plants die and decay, and thus help to build up the soil. Roots of trees sometimes work their way into crevices of the rock and, growing there, split off great pieces. Roots also secrete a kind of acid that helps to dissolve the rock. The gases in the air help in breaking up the rock, thus forming 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 Hatch, Kirk Lester, 1871- [from old catalog]; Haselwood, John Adam, 1867- [from old catalog] joint author. Chicago, Row, Peterson & company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectagriculture, bookyear
