Geology Reference
In-Depth Information
Fig. 3
Tassili
a
d
Various
geomorphological types of Tassili
sandstone (
a
Cliffs with grottoes;
b “
Cathedrals Walls
”
,
c
Canyon,
d
Sculptures of elephants);
e
and
f
Tassili rupestral engravings
(
e
Shepherd leading his flock and
f
Elephants)
-
Some of the important geosites that should be highlighted
are as follows (Perret
1935
):
(i)
(iv) Djanet, the capital of Tassili, located in the northwest
of Hoggar, is a city where the oldest part, now in
ruins, is built on blocks of Pan-African granites; in
the Valley of Idjeriou River is a beautiful oasis
bounded by spectacular cliffs.
the canyon of Djaret wadi; its average width is about
200 m and its depth is
ca
150 m; faults in the wadi
extend over 60 km of length;
(ii)
the canyon of Iherir wadi, resistant rock units have
resulted in the preservation of the steep cliffs; at the
bottom of deep gorges there is a wonderful oasis
named Iherir;
2.3
The Northern In Ouzzal Massif
(iii)
among the most surprising rock formations of Tassili
are the
Located in western Hoggar, the In Ouzzal terrane forms an
elongated N-S trending block more than 450 km long and
80 km wide around the In Hihaou massif. It contains the
oldest rocks in Algeria (2.7
or
irrekanes
of Tuareg; they
are huge sandstone outcrops standing on sandy
wadis, like the bow of a ship; their landscapes, ero-
ded and sculpted by the wind, sand and water,
present a combination of weathering and erosion
features; these
“
stone forests
”
3.2 Ga) (Peucat et al.
1996
). It is
an example of Archaean crust remobilized during very-high-
temperature metamorphism related to the Paleoproterozoic
orogeny (2 Ga). It is composed of two Archaean units, a
lower crustal unit composed essentially of enderbites and
-
'
'
stone forests
house the main rock
painting sites; and
