Chapter III: 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