Mass Wasting - Hydrogeology: Objectives, Methods, Applications - page 267

Figure 128 1998 collapses in Mougins (Alpes-Maritimes). Cross-section of the highway in
the area around the problems.
1-impermeable basement, 2-karstifi ed Muschelkalk limestone, 3-Muschelkalk marl and
dolomite, 4-Keuper gypsic masses, 5- Keuper clayey marl, 6-colluvium and anthropogenic
fi ll, 7-piezometry of the Triassic aquifer.
which also revealed that the gypsum and limestone aquifers drain to the
Carimaï spring, 3.7 km away. The existence of these drainage conditions
is also supported by piezometric surveys (Figure 129). (Mangan and Gilli,
unpublished).
3.4.4 Karstifi cation of the unit and cause of the problems
The in-depth study of the problems, through investigation and historical
research, enabled the identifi cation of a great number of indicators of
previous surface disorders, widely distributed over the areas of outcropping
Keuper (Figure 127).
A detailed examination of the structural conditions revealed that these
collapses are essentially concentrated in sectors enclosing large water-
bearing gypsiferous lenses, offering similarities in supply and drainage.
Their supply is, indeed, ensured by aggressive water from their eastern side
with a low mineral content and/or by losses from the stream network, and
their drainage occurs towards the deep Muschelkalk aquifer, with which
are established direct contacts (sedimentary or tectonic).