24
The Historical Background
(especially of its northern part) became very adaptable and thus highly competitive. This is one of the main reasons for its success in the encounter with the
Mediterranean biota.
1.4 The Pleistocene and Postpleistocene
History of the Isthmus of Suez
One ofthe most amazing aspects of the subject under study is the fact that an
isthmus some 160 km wide with a maximum elevation of 23 m and built up
entirely from sediments and sedimentary rock could act as a barrier between the
Mediterranean and the Red Sea fauna for at least the whole of the Pleistocene and
a considerable part of the Pliocene. At high eustatic sea levels one has to assurne
that the Isthmus of Suez was flooded and a continuous aquatic connection existed
between the Mediterranean and the Gulf of Suez. Conversely, at low eustatic
levels, with the whole of the Gulf of Suez dry, at least an additional 250 km was
added to the separating dry land. Nothing is known about tectonic movements in
this area, which is unfortunate, since obviously a vertical change of even a few
meters could be of considerable importance. On the other hand, if the Isthmus
can be seen as a product ofthe depositional activity ofthe Nile, then the regime of
this big river was of primordial importance in the history of the Isthmus. For
example, increased depositional or erosional cycles played a major role. The
present flood regime of the Nile was established around 12,500 BP (Fairbridge,
1972).
In fact, wh at is now considered the Isthmus of Suez is part of the old Delta of
the Nile. As the main flow of the Nile gradually shifted from the Eastern Delta
branches to the Western or Rosetta and Damietta branches, two old branches
were gradually left dry by the river: the Wadi Tumilat branch, which flowed due
east and emptied in the present Lake Timsah, and the Pelusian branch, which had
anortheastern course and emptied in the Gulf of Tineh (Gulf of Pelusium) some
30 km east of Port Said. The Sirbonic Lagoon (Sabkhat el Bardawil), which now
occupies about 200 km of the north Sinai coast, was doubtlessly fed directly at
times by Nile Delta waters. A third dried-up branch-the Tanitic branchopened in the area where Port Said stands today.
One body of knowledge relates to the history of the Nile fluviatile regime.
Butzer dedicated several writings (1951, 1959, 1966, 1971) to this subject. It appears that the high fluviatile terraces or the cutting in ofthe river were determined
in the upstream region by changes in the amount of precipitation in the EastAfrican mountains and the changing connections with the tributaries, while in the
downstream and delta region the main influence was that ofthe eustatic sea levels.
Nile terraces indicate a + 35 m level in the Delta which Butzer assigns to the
Tyrrhenian, and also a + 10-+ 15 m level which corresponds to the Second Tyrrhenian or Riss-Würm Interglacial. Of utmost importance to our subject is the
finding of a + 11 m gravel terrace at el Abassa on the Wadi Tumilat Delta branch.
One thus has to assurne that in the last interglacial the Isthmus was eventually
covered by water to a depth of about 10 m. If, therefore, one can assume that
The Historical Background
(especially of its northern part) became very adaptable and thus highly competitive. This is one of the main reasons for its success in the encounter with the
Mediterranean biota.
1.4 The Pleistocene and Postpleistocene
History of the Isthmus of Suez
One ofthe most amazing aspects of the subject under study is the fact that an
isthmus some 160 km wide with a maximum elevation of 23 m and built up
entirely from sediments and sedimentary rock could act as a barrier between the
Mediterranean and the Red Sea fauna for at least the whole of the Pleistocene and
a considerable part of the Pliocene. At high eustatic sea levels one has to assurne
that the Isthmus of Suez was flooded and a continuous aquatic connection existed
between the Mediterranean and the Gulf of Suez. Conversely, at low eustatic
levels, with the whole of the Gulf of Suez dry, at least an additional 250 km was
added to the separating dry land. Nothing is known about tectonic movements in
this area, which is unfortunate, since obviously a vertical change of even a few
meters could be of considerable importance. On the other hand, if the Isthmus
can be seen as a product ofthe depositional activity ofthe Nile, then the regime of
this big river was of primordial importance in the history of the Isthmus. For
example, increased depositional or erosional cycles played a major role. The
present flood regime of the Nile was established around 12,500 BP (Fairbridge,
1972).
In fact, wh at is now considered the Isthmus of Suez is part of the old Delta of
the Nile. As the main flow of the Nile gradually shifted from the Eastern Delta
branches to the Western or Rosetta and Damietta branches, two old branches
were gradually left dry by the river: the Wadi Tumilat branch, which flowed due
east and emptied in the present Lake Timsah, and the Pelusian branch, which had
anortheastern course and emptied in the Gulf of Tineh (Gulf of Pelusium) some
30 km east of Port Said. The Sirbonic Lagoon (Sabkhat el Bardawil), which now
occupies about 200 km of the north Sinai coast, was doubtlessly fed directly at
times by Nile Delta waters. A third dried-up branch-the Tanitic branchopened in the area where Port Said stands today.
One body of knowledge relates to the history of the Nile fluviatile regime.
Butzer dedicated several writings (1951, 1959, 1966, 1971) to this subject. It appears that the high fluviatile terraces or the cutting in ofthe river were determined
in the upstream region by changes in the amount of precipitation in the EastAfrican mountains and the changing connections with the tributaries, while in the
downstream and delta region the main influence was that ofthe eustatic sea levels.
Nile terraces indicate a + 35 m level in the Delta which Butzer assigns to the
Tyrrhenian, and also a + 10-+ 15 m level which corresponds to the Second Tyrrhenian or Riss-Würm Interglacial. Of utmost importance to our subject is the
finding of a + 11 m gravel terrace at el Abassa on the Wadi Tumilat Delta branch.
One thus has to assurne that in the last interglacial the Isthmus was eventually
covered by water to a depth of about 10 m. If, therefore, one can assume that