Paleodunes atop River Sediments by Faysal Bibi

Ice age dune deposits (aeolian sands) lying unconformably on late Miocene (ca 7Ma) river sediments of the Baynunah Formation.

Abu Dhabi Emirate, United Arab Emirates.

The dune deposits at the top of the outcrop are made up of cemented oolites which were blown in from the Persian Gulf seabed. During Ice Age maxima, global sea levels were very low and the Persian Gulf dried out. Strong northern winds then picked up sands and grains from the dry seabed and blew them onto land to form large dunes which in some cases cemented themselves in place.

The Baynunah Formation sands and clays (reddish and whitish levels towards the bottom) are remains of deposits from a large river system that flowed through this now-hyperarid region some 7 million years ago. From the Baynunah Formation our team has recovered abundant fossils of river animals such as catfish, turtles, hippopotamus, and crocodiles.

You can zoom right in on the contact between the two types of rock, each representing a very different type of paleo-environment. The contact separating the two represents about 6 million years of missing time.