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Strike of quartzite bed, dip 80° towards N10°E

Short answer

Dip direction N10°E (azimuth 10°). Strike = dip direction ± 90°, yielding azimuths 280° and 100°, so strike is N80°W (S80°E).

A quartzite bedrock dips at an angle of 80° towards N10°E. Find out the strike of the bedrock with illustration.

The strike is the direction of the horizontal line on the bed and it is always at 90° to the dip direction.

Given: Quartzite bedrock dips 80° towards N10°E. Dip direction = N10°E, azimuth = 10°.

Strike=dip direction±90°=10°−90°=280° or 10°+90°=100°\begin{aligned} \text{Strike} &= \text{dip direction} \pm 90° \\ &= 10° - 90° = 280° \ \text{or}\ 10° + 90° = 100° \end{aligned}

These two azimuths (280° and 100°) are the two ends of one line, so the strike is N80°W (S80°E).

                    N
         N80W \     |     / dip N10E
                \   |   /
                  \ | /
  W ----------------+--------------------- E
                    | \
                    |   \
                    |     \ S80E
                    S
   ( \ = strike line N80W-S80E,  / = dip direction N10E, at 90 deg to strike )

Answer: Strike = N80°W (S80°E).

✓ Answer checked by Claude Opus 5.5 (high effort)

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