Geoscience Reference
In-Depth Information
But the result obtained, although vitiated by error, suffices to show that a
long time is needed for a soil to be formed, even if shallow. Furthermore,
we know that little time is needed to remove the soil by erosion. The
soil is a non-renewable resource!
Calculations of age based on rates of export have also been done with
iron and aluminium (Tardy 1969; Gac 1979; Legros 1982; Lucas 1989).
These elements are very slightly soluble and thus permit estimation of
the great ages that concern tropical soils and the degraded old soils of
temperate regions. A review of studies has been published (Bourrié and
Lelong 1994).
CONCLUSION
Scientists are thus equipped with methods for characterizing their soils
morphologically and chemically (we have said that biology is outside
our field of discussion). They have also tried to calculate the age of soils
and have estimated the substances the soils had lost over time. They
have also reconstructed geochemical transformations in the laboratory
by using experimental approaches. In short, they are equipped with
the tools for attempting to understand long-term changes that form the
subject matter of this topic.
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