Fossil of 37 million years old whale skeleton (more than65ft long) Found in Wadi Al Hitan, Egyptian desert.

The geology of the valley gives rise to the scenery, with wind and water erosion producing spectacular cliffs and buttes. The rocks present at Wādī al-Ḥītān are all Middle to Late Eocene in age and comprise three main rock units. The Gehannam Formation comprises open marine mudstones, which are largely present on the flatter ground to the east of the public park. The rock unit that contains most of the whale fossils is the Birket Qarun Formation. This comprises yellowish open marine sandstones that form most of the cliffs and buttes.[13] The monotony of these sandstones is broken by a white layer full of well-preserved animal burrows (previously thought to be mangrove roots) and a layer of black mudstone above that.[9] When the cliffs of the Birket Qarun Formation are followed to the East, they are replaced by Gehannam Formation mudstones, indicating a change in water depth from shallower to deeper in that direction.[13] The tops of the higher cliffs are within the Qasr el Sagha Formation, which comprises dark mudstones alternating with limestones full of shells and represents a lagoonal environment.[13]