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How to Determine the Steepness of the Geologic Structure

Rock structures can be complex and full of folds and twists. Although original deposits may be laid down as horizontal layers, such as the slit in the bottom of a lake, geological processes often twist and distort them into complex features, producing folds consisting of synclines and anticlines. Geologists examine not only the types of rocks present in an area, but also the directions and angles of their folds and faults. This helps to unravel the history of each geological structure.

Things You'll Need

Compass clinometer

Instructions

- 1
  Imagine a horizontal line across the rock face. Geologists call this the "strike" of the structure. Now imagine a vertical line perpendicular to the strike. This is the direction in which the structure slopes. Geologists refer to this as the "direction of dip."
- 2
  Rest the compass clinometer against the rock surface so that it is perpendicular to the strike and aligned with the direction of dip. Record the angle indicated by the white end of the clinometer needle. This is the dip angle, or the angle of steepness of the geological structure.
- 3
  Repeat the measurement at two more locations. Add the three readings together and divide by three to find the average reading. This reduces errors due to minor irregularities on the rock surface.

Rocks & Minerals