A Treatise on Rocks, Rock-Weathering and Soils #255325

To the one, these residues are essential to the life and well being of man through furnishing the soils from whence is derived directly and indirectly the food for life's sustenance to the other they are but transitory phases in the earth's his tory, representing the materials from which, through a process of fractional separation by running waters, have been made up the thousands of feet of secondary rocks which to-day occupy so large a portion of its surface.