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Strike of limestone bed dipping S55°E

Short answer

Dip direction is S55°E (azimuth 125°). Strike is always perpendicular to dip, so N35°E (azimuth 35°) or S35°W. Strike = N35°E (S35°W).

A limestone rock bed dips towards S55°E. Find its strike direction with a figure.

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

Given: Limestone bed dips towards S55°E. Dip direction = S55°E, azimuth = 125°.

Strike=dip direction±90°=125°−90°=35° or 125°+90°=215°\begin{aligned} \text{Strike} &= \text{dip direction} \pm 90° \\ &= 125° - 90° = 35° \ \text{or}\ 125° + 90° = 215° \end{aligned}

These two azimuths (35° and 215°) are the two ends of one line, so the strike is N35°E (S35°W).

              N
              |
              |   strike line (N35E)
              |  /
     W -------+-/------ E
              |/
              |  dip direction (S55E)
              S

Answer: Strike = N35°E (S35°W).

✓ Answer checked by Claude Opus 5.5 (high effort)

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