The apparent dip of a plane is measured to be 45° towards NE. The true dip of the plane is
- 55° towards SSW
- 40° towards NNE
- 48° towards ENE
- 40° towards E
The Correct Option is C
Solution and Explanation
The problem involves determining the true dip of a plane from its apparent dip. In geology, dip is the angle at which a planar feature is inclined from the horizontal plane. The apparent dip is observed in a direction oblique to the true dip, which requires correction to find the actual orientation.
Given:
- Apparent dip = 45° towards NE
We need to find the true dip from the given options. The direction of an apparent dip indicates that it is not aligned with the true dip. The corrected angle and direction will reveal the true dip. Usually, the formula to derive the true dip (\(\Theta_t\)) from the apparent dip (\(\Theta_a\)) is:
\(\tan(\Theta_a) = \tan(\Theta_t) \cdot \cos(\alpha)\)
where \(\alpha\) is the angle between the strike direction and the direction of apparent dip. However, since directional information can be synthesized without needing this formula based on the compass point and the logical understanding of dip orientation, we proceed with logical exclusion:
- The apparent dip is towards NE, implying the true dip could be closer to the east or north direction based on the compass quadrants and typical plane structures.
- Examining the options, we see:
55° towards SSW
- : Opposite direction, unlikely correct.
40° towards NNE
- : Closer to north but less inclination than apparent dip.
48° towards ENE
- : Closer to east, and inclination slightly more robust than the apparent dip, plausible after correction.
40° towards E
- : Eastward is logical, but the inclination is lower.
- The correct choice reflects both the logical intercept with the compass direction and the corrected angle value closer to the apparent dip but adjusted for true orientation.
- Therefore, the true dip is 48° towards ENE.
Based on all deductions, the correct answer aligns with the geometrical logic of strike and dip.
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