Question

The apparent dip amount of a limestone bed in the direction 010° is 30°. If the bed strikes 320°, the value of true dip amount in degrees is ............. (Round off to nearest integer)

Hint:

For true dip calculation, use the relationship between apparent dip and strike, then apply trigonometric formulas.

Answer 1

Step 1: Use the formula for true dip.
The true dip (\( \delta \)) can be calculated from the apparent dip (\( \delta_{\text{apparent}} \)) using the relation: \[ \tan(\delta_{\text{apparent}}) = \tan(\delta) \sin(\theta) \] where \( \theta \) is the angle between the plane of apparent dip and the plane of true dip. The relationship between apparent dip and true dip can be simplified as: \[ \tan(\delta_{\text{apparent}}) = \tan(\delta) \sin(\theta) \] Step 2: Calculate true dip.
Given the strike is 320° and the apparent dip direction is 010°, the angle \( \theta \) is: \[ \theta = 320° - 010° = 310° \] Now use the apparent dip of 30°: \[ \tan(30^\circ) = \tan(\delta) \sin(310^\circ) \] Solving for \( \delta \), the true dip comes out to be: \[ \boxed{17} \] Final Answer: \[ \boxed{17} \]