Paleocurrent

A paleocurrent or paleocurrent indicator is a geological feature (typically a sedimentary structure) that helps one determine the direction of flowing water in the geologic past.

This is an invaluable tool in the reconstruction of ancient depositional environments.

[1] There are two main types of paleocurrent indicators: Paleocurrents are usually measured with an azimuth, or as a rake on a bedding plane, and displayed with a Rose Diagram to show the dominant direction(s) of flow.

This is needed because in some depositional environments, like meandering rivers, the paleocurrent resulting from natural sinuosity has a natural variation of 180 degrees or more.

[2] Below are a partial list of common paleocurrent indicators:

Bidirectional wave ripple, Nomgon , Mongolia
Flute cast, showing paleocurrent to the upper right of pic
Parting lineation, from lower right to upper left; Kayenta Formation , Canyonlands National Park .