Section Xi.—Upper Eocene — Lower Oligocene—

E.—Fluvio-marine Series.—Nature of sediments, Interbedded basalts in upper part. Character of its invertebrate fauna. Conditions of deposition of series. Continuance of similar conditions to Miocene and even Pliocene times. Bone-beds at base of series. Association of skeletons of animals and forest trees. Preservation of remains. Analysis of fossil bones. Relation of Fluvio-marine series to underlying stage. Characteristics of the group. Its development in the field. Its slight development at Elwat Hialla. Section near Elwat Hialla. Constant northerly dip. Organic (molluscan) remains 9 and 14 kilometres north of Qasr el Sagha. Detailed section from near Qasr el Sagha to Widan el Faras. Determinations of mollusca from the series. Tripartite character of the series west of Widan el Faras and Qasr el Sagha. Occurrence of calcite, gypsum and chalcedony. Tabular chert and flint. Ancient workings. Extent of basalt. Silicified trees 53

F.—Age of the Fluvio-Marine Series.—Difficulty in the determination of age owing to paucity of fossils. Zittel’s tabulation of “Schichten von Birket el Qurûn” as Oligocene. Mayer-Eymar’s age determinations. Schweinfurth’s comparison of the series with the Scutella beds of Der el Beda near Cairo. Blanckenhorn’s determinations. The stratigraphical position of the series and relationship to Qasr el Sagha series. Stratigraphically lower than the Lower Miocene of Mogara. Whole complex in all probability of Upper Eocene and Oligocene age, the transition being at or near the basalt sheets 63

G.—The Position of the Land Mass from which the Mammals were derived.—Proximity of continental land. Absence of branches on fossil trees. Massif of Abu Roash perhaps an island to the north. Extension of Eocene sea. Continual retreat of the sea northwards. Rivers emerging from the land. Number and positions of such rivers doubtful. Evidence for river passing from the modern oasis of Baharia through Gar el Hamra to the Fayûm. Lacustrine and fluviatile deposits along the course. Huxley’s theory of immigration and invasion of animals into Africa. Fayûm animals belong to an extinct African fauna of Tertiary times. Contains the earliest and most primitive forms of elephants and other groups. Emigration and immigration. Prof. Osborn’s theory of the African continent as a centre of radiation. Confirmation by the Fayûm mammal discoveries. List of new species obtained from the Fayûm 65

H.—The Absence of Miocene deposits in the Fayûm.—The Fayûm a land area in Miocene times. Miocene deposits of Mogara. Lithological similarity. Probable persistence of geographical conditions 71