Geoscience Reference
In-Depth Information
in Australia. This soil is observed in Africa south of the Sahara: Central
Africa, northwestern Côte d'Ivoire, southern Mali… It pertains to the
Surface of the soil at
times reduced to this
level
A horizon
,soft and red (kaolinite + goethite),
at times absent because eroded.
B horizon
soft and red, microstructured, non
argic (no clayey surfaces or coatings); contains,
like the A, kaolinite and goethite. Sometimes
absent because of erosion.
0
Zone of dismantling
of the cuirass = gravelly
or brecciated zone
5 m
Reddish cuirassed zone
Above
: massive = ferricrete or duricrust =
petroplinthite = haematite +/- aluminous
: Carapace (can be crushed by hand) =
scoriaceous and vesicular zone
Below
Mottled zone
called pisolitic, slightly hard
(= plinthite), with ferruginous nodules + matrix
of quartz and kaolinite
10 m
Lithomarge
or fine saprolite or even variegated
clays ( ):
: pedotubules (voids + brown
goethite + pink kaolinite) = allotérite
with quartz more or less
dissolved (rock structure preserved)
mottled clay
Pedostructure
Lithostructure
15 m
Isaltérite
or : rock structure preserved.
Very high porosity. Loss of matter.Feldspars
and micas replaced by kaolinite.Quartz
retained.Possible crystallization of gibbsite if
aluminium is in excess
saprolite
20 m
Traces of a network of partitions
Hard rock
in place, unweathered
Fig. 5.1
Complete profi le of cuirassed Ferralsol (Plinthic Ferralsol). The horizons are to be
understood starting from the bottom. Terminology varies with author. The drawing attempts to
give approximate equivalents.
