||Substrate materials may be so extensively altered (as in deep weathering profiles)
that it may be difficult or impossible to determine their original nature. Certain
constituents may be either depleted or enriched. Thus, in many laterite profiles,
some horizons are ferruginised, partially ferruginised and partially kaolinised, and
the pallid zone kaolinised. Silicification may also be associated with deep weathering
profiles although not exclusively so; for instance, some limestones may be variably
silicified. In contrast, calcification, which is widespread in parts of southern Australia,
is not usually associated with deep weathering.