Stromatolites in Sedimentary Geology:
 Paleo-Current Indicators

    Stromatolites, in effect, can indacte the direction of paleo-currents.  They can form in elongate forms that show the trend of currents, or they can be inclined and asymmetric and can be used to determine the sense of direction, basically landward or seaward, and the orientation of the shoreline.  The stromatolites in Shark Bay, Australia have been used to reconstruct a paleocurrent system in proterozoic sediments based on their shape and orientations.  It was found that their elongate elliptical, columnar structure was parralel with the direction of wave scour, and in turn normal to the shoreline.
    Although most investigations of ancient and modern stromatolites have concluded to form normal to the shoreline, some stromatolites have shown different orientations.  There have been stromatolites described from the Proterozic that are believed to have formed parallel to the coastline based on paleocurrent directions that were interpreted from associated sedimentary structures.  The elliptical shape of the stromatolites are thought to have been the result of tidal currents running parallel to the length of an elongated embayment in the Precambrian Sea.

Above:  Stromatolites of Shark Bay, Aus. (Walter, 1972)