Geoscience Reference
In-Depth Information
Soil toposequence
Haplic Vertisol
Gleyic Vertisol
Gleysol (water)
Black calcareous soil
Haplic (i.e. typic)
Vertisol
More or less Salic (Na),
Thionic (S) and Gleyic
(water) Vertisols
Marls
Colluvia on marls
Fluviatile alluvia
Marine alluvia
Fig. 6.6
Schematic organization of Vertisols of Cuba, (from Paneque y Perez 1984).
The most typical Vertisols (termed Haplic in the classifications) are
seen on marls, in the depressions of the landscape where they lie on the
weathering surfaces, formed
in situ
or lightly transported by colluviation.
In the large plains they are in fluviatile alluvium. There, when we
proceed to the lower positions, the soils are more and more marked by
excess water. Near the ocean, Vertisols progressively pass to sulphatic
and saline soils of the mangroves (see Chaps. 12 and 13).
For being weathered to smectite, the typical clay mineral of confined
environments, the parent materials must be base-rich while containing
sufficient amounts of SiO
2
. Thus Vertisols are primarily found
(Podwojewski and Baudou 1995) on:
Role of the parent material
Basalts that easily yield smectites on weathering
in situ
in dry
climate, for example in China (Long
et al.
1997) and in India
(Pal
et al.
2009);
Ultrabasic rocks poor in silica and sometimes devoid of aluminium,
but rich in Mg. In this case, the clay minerals are ferriferous
smectites in which iron partially replaces aluminium;
Marls that yield an abundant decarbonated residue often contain-
ing smectites and vermiculites. Coral reefs are also favourable
substrata (Guadeloupe). Pure, hard limestones are not suitable;
Rocks well provided with silica and bases (Ca and Mg) at the
same time: calc-schists, gabbros and
In alluvia when they are clayey and calcareous; this has been
noted earlier.
Vegetation plays a limited role or none at all in the differentiation of
Vertisols. Most of these soils are observed under prairie, but they occur
under acacia forest (Mermut
et al.
1996).
Vegetation
