Geology Reference
In-Depth Information
Fig. 6.32.
Cross section of the Sequatchie anticline interpreted with spline curves. No vertical exag-
geration.
a
Dip-domain cross section (
thin solid lines
from Fig. 6.23) and computer-smoothed spline
interpretation (
thick dashed curves
).
b
Spline curve section edited to more closely resemble the dip-
domain section
6.5
Changing the Dip of the Section Plane
If a cross section is not perpendicular to the fold axis, it is helpful for structural inter-
pretation to rotate the section plane until it is a normal section. Alternatively, it might
be necessary to rotate a normal section to vertical. The necessary relationships are
equivalent to removing (or adding) a vertical exaggeration, as done in the visual method
of down-plunge viewing.
From the geometry of Fig. 6.33, the exaggeration in a vertical section across a plung-
ing fold (Eq. 6.1) is
V
e
=
t
v
/
t
=1/cos
.
(6.8)
φ
