Geology Reference
In-Depth Information
Figure 3.40 Joint
pattern in schist. All
joints are
approximately at
right angles to the
schistosity but
otherwise random
in orientation. Pos
Selim landslide,
Malaysia. See
history.
Figure 3.41 Joints
with conjugate
shear arrangement.
At some locations
there are
measurable
displacements so
the shear joints
grade into small
Near Austin, Texas,
USA.
No visible
displacement
Local normal
faulting
Sheeting joints, which are sometimes also referred to as exfoliation
fractures, are unlike other joints in that their geometry is not pre-
de
ned by ancient geological history but instead they develop in
response to near-surface stress conditions re
ecting locally prevailing
topography (Hencher et al., 2011). These are tertiary joints, as de
ned
earlier. Sheeting joints are a striking feature of many landscapes and
they have been studied for more than two centuries (Twidale, 1973).
They run roughly parallel to the ground surface in
flat-lying and
