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.
Top Questions on Structural Geology
- The dips of the normal and overturned limbs of a horizontal-overturned antiform are 30⁰ and 70⁰, respectively. The interlimb angle of this fold is _______ degrees. (In integer)
- IIT JAM GG - 2024
- Geology
- Structural Geology
- Which of the following rock structures is/are fold(s)?
- GATE GG - 2024
- Geology
- Structural Geology
- Which of the following statements is/are CORRECT for the M-plane of any fault?
- GATE GG - 2024
- Geology
- Structural Geology
- In the fold profile section shown in the figure, 1 and 3 are the oldest and the youngest stratigraphic units, respectively. Which one of the following fold descriptions CORRECTLY matches the asymmetric fold shown in the given figure?
- GATE GG - 2024
- Geology
- Structural Geology
- The thickness of a dipping coal bed measured along a vertical drill hole is 15 m. If the dip of the coal bed is 30⁰, the orthogonal thickness of the coal bed is ___________ m. (Round off to the nearest integer)
- IIT JAM GG - 2024
- Geology
- Structural Geology
Questions Asked in IIT JAM GG exam
A magma having density of 2900 kg m\(^-3\) just reaches the surface through a two-layered crust as shown in the figure below. Assuming isostatic equilibrium, its depth of melting is .......... km. (Round off to one decimal place)
- IIT JAM GG - 2025
- Geophysics
Two boreholes A and B, both inclined towards 270°, penetrate a dipping coal bed at the same point and pass through it entirely in the sub-surface as shown in the figure below. The bed dips towards 270°. The thickness of the coal bed, measured along the borehole A is 10 m and along borehole B is 8 m. The angle between the two boreholes is 20°. The orthogonal thickness \( x \) of the coal bed is ........ m. (Round off to one decimal place)
- IIT JAM GG - 2025
- Applied Geology
A well-developed succession of laminated shale is bound by two volcanic ash beds that were precisely dated as shown in the schematic diagram given below. Assuming a constant sedimentation rate, the age of the fossiliferous limestone bed 65 m above the basal volcanic ash bed is ............ Ma. (Round off to nearest integer)
- IIT JAM GG - 2025
- Stratigraphy
The data tabulated below are for flooding events in the last 400 years.
The probability of a large flood accompanied by a glacial lake outburst flood (GLOF) in 2025 is ........... \(\times 10^{-3}\). (Round off to one decimal place)
Year Flood Size Magnitude rank 1625 Large 2 1658 Large + GLOF 1 1692 Small 4 1704 Large 2 1767 Large 2 1806 Small 4 1872 Large + GLOF 1 1909 Large 2 1932 Large 2 1966 Medium 3 2023 Large + GLOF 1 - IIT JAM GG - 2025
- Applied Geology
A satellite launching vehicle is carrying a lander for Moon mapping.
As shown in the figure below, P is the position where the gravitational forces exerted by Earth and Moon on the vehicle balance out.
The distance \( P \) from the center of the Earth is ........... \(\times 10^5\) km. (Round off to two decimal places)
- IIT JAM GG - 2025
- Applied Geology