• Dorothy Carroll
Part of the Monographs in Geoscience book series (MOGEO)


The uppermost part of the weathered rock at the earth’s surface is called soil. In “Soil Classification, A Comprehensive System, 7th Approximation” published by the U.S. Department of Agriculture in 1960 there appears the following definition of soil. It is similar to that given in Chapter 3 when describing pedochemical weathering

“Soil .... is the collection of natural bodies on the earth’s surface, containing living matter, and supporting or capable of supporting plants. At its upper limits is air or water. At its lateral margins it grades to deep water or to barren areas of rock, ice, salt, or shifting desert sand dunes. Its lower limit is perhaps the most difficult to define. Soil includes all horizons differing from the underlying rock material as a result of interactions between climate, living organisms, parent materials and relief. Thus, in the few places where it contains horizons impermeable to roots, soil is deeper than plant rooting. More commonly soil grades at its lower margin to hard rock or to earthy materials essentially devoid of roots. The lower limit of soil therefore is normally the lower limit of the common rooting of the native perennial plants, a diffuse boundary that is shallow in deserts and tundra and deep in the humid Tropics.”


Clay Mineral Soil Profile Calcium Carbonate Silty Clay Loam Residual Mineral 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Plenum Press, New York 1970

Authors and Affiliations

  • Dorothy Carroll
    • 1
  1. 1.U. S. Geological SurveyMenlo ParkUSA

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