282
Climatic Geomorphology
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Figure 12.26. Representation of a model of calcrete formation by different inputs of carbonate from
above per descensum model (in Goudie, 1973b, Figure 44).
The presence of calcified filaments, fibrous calcites and fungus microfossils testify to a
pedogenic caliche origin (Vaniman et al., 1994). A problem with this hypothesis is that
the caliche thickness is generally much greater than that of the soil; this difficulty can be
explained by a slow rate of soil erosion during caliche production.
When carbonate solutions rise through capillary action and precipitate at the surface by
evaporation, nonpedogenic caliches form, corresponding to the per ascensum model of
Transpiration
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Figure 12.27. A model of calcrete formation by capillarity rise from groundwater per ascensum model
(after Goudie, 1983b, Figure 4.5, reproduced with permission).