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Strike of quartzite bed, dip 70° towards S20°E

Short answer

Attitude is the orientation of a rock layer defined by strike and dip. Given dip direction S20°E (azimuth 160°), strike is at 90° to it, giving N70°E (S70°W). Dip amount is 70°.

Define attitude of a rock. A quartzite bedrock dips at an angle 70° towards S20°E. Find out the strike of the bedrock with an illustration.

Attitude of a rock

The attitude of a rock is its orientation in space, given by the strike (bearing of the horizontal line on the bed) and the dip (maximum inclination, with dip direction and dip amount). For lines, the attitude is given by trend and plunge.

Strike calculation

Given: dip amount = 70°, dip direction = S20°E, azimuth = 180°−20°=160°180° - 20° = 160°.

Strike=160°−90°=70°(or 160°+90°=250°)\text{Strike} = 160° - 90° = 70° \quad(\text{or } 160°+90° = 250°)

So the strike is N70°E (the same line as S70°W).

              N
              |
              |   strike line (N70E)
              |  /
     W -------+-/------ E
              |/
              |  dip direction (S20E)
              S

The dip amount (70°) does not change the strike; the strike depends only on the dip direction.

Answer: Strike = N70°E; attitude = N70°E / 70° SE.

✓ Answer checked by Claude Opus 5.5 (high effort)

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