Geology Reference
In-Depth Information
Figure 4.
The fissured layer in granites (left: Margeride, Lozère,
France)and in metamorphic rocks (right: Gokseong area, South Korea).
water infiltration. Thus, such profiles cannot develop in regions of sharp
topography where the erosion rate is higher than the one of weathering.
An important consequence of this weathering process is that, from the
hectometre scale to the regional one, these layers are parallel to the paleo-
weathering surfaces (paleo-landscape) contemporaneous with the weathering
phase and thus appear as stratified layers (Fig. 2; Wyns et al., 2004;
Lachassagne et al., 2001). Moreover, geological features (faults, dykes, etc.)
or contrasts in rock mineralogy or structure can locally modify the
characteristics (mineralogy, thickness, etc.) of the weathering profile. These
contrasts lead to differential weathering and in some cases to the development
of positive topographic anomalies such as inselbergs.
More complex weathering profiles can result from multiphase weathering
and erosion processes. In Korea for instance at least two main phases of
weathering have been identified (Cho et al., 2002; Fig. 5):
Figure 5.
Red recent weathering, related to the present topography,
intersecting an old weathering profile (Namwon area, South Korea).
