Ripple marks

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Ancient water ripple marks in sandstone, Moenkopi Formation, Capitol Reef National Park, Utah
Ancient water ripple marks in sandstone, Moenkopi Formation, Capitol Reef National Park, Utah

In geology, ripple marks are sedimentary structures that indicate agitation by water (current or waves) or wind. Ripple marks formed by water consist of two basic types:

  1. Current ripple marks are asymmetrical in profile, with a gentle up-current slope and a steeper down-current slope.
  2. Wave-formed ripple marks have a symmetrical, almost sinusoidal profile; they indicate an environment with weak currents where water motion is dominated by wave oscillations.

Ripple marks tend to be small, on the order of a few centimeters; however, there are enormous ones, such as those characteristic of the Channeled Scablands, with wavelengths as long as 100 meters.

[edit] References

  • Monroe, James S., and Reed Wicander. The Changing Earth: Exploring Geology and Evolution, 2nd ed. Belmont: West Publishing Company, 1997. ISBN 0-314-09577-2 pp. 114-15, 352.
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