Question

The dip and dip direction of the lee side of a straight crested ripple on modern sediments are found to be 15$^\circ$ and N10$^\circ$W, respectively. Considering unidirectional water movement, the flow direction is towards:

• A. N10$^\circ$W
• B. N70$^\circ$E
• C. S10$^\circ$E
• D. S70$^\circ$W

Hint:

For unidirectional ripples, remember: flow direction = dip direction of the lee side.

Answer 1

The Correct Option is A

Step 1: Ripple geometry.
In current ripples, the lee side (downstream side) is the inclined surface where sediment avalanches down. The dip direction of the lee side always points in the direction of water flow.

Step 2: Interpret dip direction.
The dip direction given is N10$^\circ$W. Therefore, the flow direction is directly towards N10$^\circ$W.

Step 3: Eliminate alternatives.
- N70$^\circ$E, S10$^\circ$E, and S70$^\circ$W are not consistent with the observed dip direction. - The lee slope unambiguously indicates flow direction $\Rightarrow$ N10$^\circ$W.

Final Answer:
\[ \boxed{\text{N10$^\circ$W}} \]