as indicators of Late Ordovician sedimentary environments in Northwest Estonia.
Ripple marks are typically generated by currents moving in one direction or by the to-and-fro motion of waves in shallow water to depths of a few tens of feet at the most.
Ripple marks and mud cracks are preserved in the Precambrian Bass, Hakatai, Dox, and Nankoweap Formations.
Canyon walls may also contain other structures, such as fossilized ripple marks
The sedimentary structures noticed include laminations, cross bedding, ripple marks
, burrows, liesgang rings (?
Fossil ripple marks are important features indicative of a specific depositional environment of an ancient basin.
In Estonia fossil ripple marks have been identified in Cambrian and Devonian siliciclastics as well as in Ordovician and Silurian carbonate rocks.
Key features of these specimens include flaked surfaces running in two or more directions and ripple marks
, cracks and protrusions clearly resulting from the impact required to detach flakes from stone.
Mark and Ali (1961) and Ali (1962) studied the Tanawal Formation near Tarbela as well in the presently studied area and described preponderance of well- bedded quartzites with excellent cross bedding and ripple marks.
The sequence is characterized by common cross bedding and ripple marks.
Photos from underwater cameras showed that these storms erased animal tracks and created ripple marks
in the sediments.
Bioturbation, ripple marks
and mudcracks are observed in Mianwali Formation, while cross bedding is dominant in the overlying Tredian Formation.