Problem: Dipping planes show a different dip depending on the
orientation of the viewer, i.e. apparent dip. The maximum dip on a plane
is the "true" dip. Often you may not be able to measure the true dip but
you can estimate the true dip if you have two apparent dips
Question: Graphically derive the true dips from the following apparent trends and plunges (lines)?
1. N60E/20 N75E/32
2. N60E/67 N4W/34
3. N40W/35 N85W/15
4. N75E/28 S70E/43
5. S70E/43 S2W/25
6. S35W/24NW S15W/13
2. THREE-POINT BED PROBLEM
Problem: A plane can also be defined provided that the position
of three points on the plane are known. The plane that is common to all
three is unique.
(a) Calculate the strike and dip of the gas-bearing sand layer with the following information
Three land wells (Echidna-1, Emu-2 and Pollard) located at the same height have drilled through the same layer of methane-bearing sand. Emu-2 lies 200 m from Echidna-1 along an azimuth of 050deg.. Pollard is found 240 m from A along an azimuth of 160deg.
Following are the different depths at which the gas-bearing sand were
found in each well:
Echidna-1: 120 m
Emu-2: 180 m
Pollard: 320 m
I recommend you use a scale on your work of 1:2,000
(b) Using the attached Map (#15) calcualte the strike and dip of
the coal seam.