Question

The rake (pitch) of slickenslides exposed on a moderately dipping fault plane is the angle between

• A. the magnetic north and strike of the fault plane measured on a horizontal surface
• B. the strike of the fault plane and the slickenslides measured on the fault plane
• C. the strike of the fault plane and the slickenslides measured on a vertical plane
• D. the trend and the plunge directions of slickenslides measured on the fault plane

Hint:

The rake is always measured on the fault plane and refers to the angle between the slickenslide direction and the strike of the fault.

Answer 1

The Correct Option is B

Step 1: What rake means.
The rake, or pitch, is an angle measured right on the fault plane itself. It is not measured in the air or on some other surface.

Step 2: The two lines involved.
On that plane we have the strike line and the slickenside grooves left by movement. The rake is the angle between these two, taken on the plane.

Step 3: Drop the magnetic north idea.
Using magnetic north and the strike on a flat surface gives a bearing, not a rake. So that option is about something else.

Step 4: Drop the vertical and trend or plunge ideas.
Measuring on a vertical plane is wrong, because rake lives on the fault plane. Trend and plunge describe a line in space, which is a different way to fix the slip line.

Step 5: Final choice.
So the rake is the angle between the strike and the slickensides, both read on the fault plane.
\[ \boxed{\text{The strike of the fault plane and the slickenslides measured on the fault plane}} \]