Jebel Qatrani Formation

The Jebel Qatrani Formation (also Gebel Qatrani) is a palaeontological and geologic formation located in the Faiyum Governorate of central Egypt.
Conformably overlying the Qasr el Sagha Formation. It is exposed namely between the Jebel Qatrani escarpment and the Qasr el Sagha escarpment, north of Birket Qarun lake near Faiyum.
Geology.
These rocks were laid down in the Eocene-Oligocene period (Priabonian - Rupelian). This formation was originally thought to be between 35.4 and 33.3 million years old, based on initial analysis of the formation. However, analysis by Erik Seiffert in 2006 concluded that the age of the Jebel Qatrani Formation should be revised. His assessment of more recent evidence indicates an age for most of the formation of between 30.2 and 29.5 million years ago, placing it almost entirely in the Early Oligocene. Seiffert states that only the lowest 48 metres was laid down in the Eocene, but recent opinion holds the original hypothesis of a sediment straddling the Eocene-Oligocene boundary to be correct.
Mostly sandstones deposited by meandering rivers and seasonal lakes, the lower (Eocene) part of the formation represents a woodlanded ecosystem of which much petrified wood also remains. In contrast, the upper (Oligocene) layers present indication of much drier and cooler conditions, with savanna replacing the woodland for several million years before the climate turned wetter and warmer again and the forests regrew.
The fauna changes also notably during this time, seemingly coincident with the Eocene–Oligocene extinction event recorded in Eurasia.