. Elementary lessons in the physics of agriculture. Agricultural physics. Fig. 30. stone hills, while Fig. 31 shows the same facts for a more level limestone surface. On examining the rocks of almost any. quarry they are found to be divided into blocks of varying sizes by fissures or breaks which owe their origin to a general shrinkage of the rocks and to movements of the earth's sur- face layers. These are the first steps in soil formation, and :ire plainly shown in Figs. 32 and 33. They exert a great in- fluence in rock destruction and soil formation by furnishing easy access for water and t
. Elementary lessons in the physics of agriculture. Agricultural physics. Fig. 30. stone hills, while Fig. 31 shows the same facts for a more level limestone surface. On examining the rocks of almost any. quarry they are found to be divided into blocks of varying sizes by fissures or breaks which owe their origin to a general shrinkage of the rocks and to movements of the earth's sur- face layers. These are the first steps in soil formation, and :ire plainly shown in Figs. 32 and 33. They exert a great in- fluence in rock destruction and soil formation by furnishing easy access for water and the roots of trees to their interior, where the first by freezing and the second by growth expand and break the blocks into smaller fragments. Moving ice, in the form of glaciers, has done a vast amount of rock grinding, the present soil of all except the southwestern portion of our own state being the altered surface of a thick mantle of bould- ers, gravel, sand and clay formed, transported and spread out by glacial action and the waters from the melting ice. Then there are many animals which have contributed largely to this rock grinding and soil formation. Darwin, through a long and careful study, reached the conclusion that in many parts. 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 King, F. H. (Franklin Hiram), 1848-1911. [Madison, Wis. ] The author
Size: 2826px × 884px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishermadis, bookyear1894
