Geoscience Reference
In-Depth Information
1. General orientation
W
E
Determine the general direction of strike to
within
c
. 20
°
by noting where the maximum
dip lies; the strike is at 90
°
to this. In some
cases it may be necessary to smooth out
the variations on the surface by placing a
notebook or clipboard on the bedding plane
but take care to ensure that this is not
biased by a small irregularity. Hammer
shows the plane chosen in this case.
2
2. Strike direction
Place the long edge of the compass-
clinometer down where you roughly
estimate the line of strike is. Using the round
spirit level, position the compass exactly
horizontal by both:
(i) Tilting the compass about its short axis
so it is horizontal (as shown by the red
arrow);
(ii) Slightly pivoting the long edge of the
compass in contact with the bedding plane
about its central point (as shown by the red
arrow) to obtain the exact line of strike
within your 20
°
window.
Figure 2.7
How to use the Brunton-type compass-clinometer to measure the orientation and dip of a plane
using the contact method. The parts of the compass-clinometer are shown in Figure 2.3 a-c.
