Geoscience Reference
In-Depth Information
Table 6.1 Contd...
86-136
67.9
16.5
13.8
1.7
C
16.3
136-174
72.0
17.0
7.4
3.6
C
10.0
174-200
65.8
27.3
4.2
2.8
C
50.9
pH
O.M., %
CEC
SiO
2
,
%
Al
2
O
3
,
% Fe
2
O
3
, %
0-33
6.6
4.9
90.6
51.1
16.5
7.7
33-53
7.4
0.9
87.0
56.3
16.9
8.0
53-86
7.9
0.4
84.5
53.4
15.0
7.9
86-136
8.5
0.3
74.7
48.6
14.3
7.0
136-174
8.7
0.3
73.9
50.5
15.1
7.3
174-200
8.7
0.1
82.8
57.2
15.5
7.8
Vertisols are often associated with
gilgai relief
. This name was given by
the Australian Aborigines. The surface of the land develops hollows and
bumps with a vertical unevenness of 10-60 cm and a lateral spacing
between bumps of 1-7 m. The bumps are
microhighs
and the hollows
are
microlows
(Fig. 6.4).
Gilgai relief
The gilgai relief disappears under very humid or very dry climates
that do not allow the soil to swell or shrink. It is absent in the Vertisols
of New Caledonia (Podwojewski 1995). Neither does it exist in Vertisols
of France. The shrinkage cracks are also less active near the boundaries
of the area within which this soil is distributed.
30 to 50 cm
Surface horizon
1 m
3 to 7 m
Deeper horizons
Bump
Intermediate
zone
Hollow
Total depth of soil: about 5 m
Fig. 6.4
Lateral and vertical organization of a Vertisol with gilgai microrelief (Kovda
et al
.
1996).
