The Esna Shale of the Esna-Idfu region, Nile Valley, Upper Egypt, long has been treated as a single formation. Lithological and paleontological data justify raising the Esna to group status and subdividing it into two formations, the Sharawna Shale (Maestrichtian), below, and the Owaina Shale (Paleocene), above. The two formations are separated by a thin conglomerate and have distinctive lithologic characteristics and different faunas.
The base of the Esna Group, as redefined, is the top of the Sibaiya (phosphate) Formation (Senonian). The top is the base of the Thebes calcareous shale member of the Thebes Formation (Eocene). The Thebes calcareous shale member usually has been included with the Esna, but is excluded here on paleontological-lithological grounds.