20
The Historical Background
tropical and tropical coasts. This statement should find support in the fossil
findings of the above-mentioned mollusc species. It seems obvious, however, that
at least some of the "Senegalian" invaders could in fact survive the Würm glacial.
There is alm ost no proven case in which a faunal addition from the nearby
Red Sea occurred during the whole Pleistocene. If there were such immigrants,
they left no traces in the fossil record. The chronically impoverished Eastern
Mediterranean received its faunal supply exdusively from the west. The highest
elevation on the Isthmus of Suez is only 23 m but one cannot exclude eustatic
situations in which the Mediterranean communicated with the Red Sea. High
shores at such altitudes are known both from Egypt and from the Lebanon.
Fluviatile terraces of the Nile also indicate high Mediterranean levels. It will be
necessary therefore to take a doser look at the Pleistocene of the Isthmus of Suez
in order to und erstand why there is no sign of an interchange between the two
seas at high eustatic levels.
To conclude this chapter, however, emphasis must be laid on the fact that the
"Lessepsian" period of the Mediterranean Quaternary-a period beginning with
the opening of the Suez Canal-is the first and only phase in the whole PlioPleistocene complex where a massive faunal inflow from the Indo-Pacific occurred. The 45 1 species ofmolluscs which have already invaded the Eastem Mediterranean can give us a measure of the geological significance of this man-made
dispersal event. Future geologists might look at it one day as areversal of a basic
paleozoogeographic pattern perhaps as old as the whole of the Neogene Period,
spanning not less than some 20 million years.
1.3 The Pleistocene of the Red Sea
The Red Sea, isolated from the Mediterranean at least since the earlier stages
ofthe Pliocene, had an equally agitated Pleistocene history-along different lines,
however.
The movements wh ich led to the opening of the Red Sea Rift were especially
active during the Pleistocene and for practical purposes they may be considered
as still continuing.
Friedman (1968) considers that along the Sinai coast of the Gulf of Aqaba
some minor tectonic movements occurred as late as 5000 years ago. A raised coral
reef near Elat was radiocarbon-dated to 4770± 140 years, (Friedman, 1968).
H urne (1916) described raised Pleistocene coral reefs at an altitude of 200 m-much
above any possible high eustatic terrace. The sequence of high and low eustatic
levels, which is such a useful tool for understanding the Pleistocene history in the
Mediterranean and elsewhere, is therefore of little use in the Red Sea. It can also
be assumed that in the Straits of Bab el Mandab, which connect the Red Sea to
the Indian Ocean, tectonic activity continued throughout the period and the
depth and width of the sill area also changed.
1 Note added in proof: More species are added to the-list by Barash,AI., Danin,Z.: Additions
to the knowledge of Indo-Pacific Molusca in the Mediterranean. Conchiglie, Milano
13 (5-6), 85-116 (1977).
The Historical Background
tropical and tropical coasts. This statement should find support in the fossil
findings of the above-mentioned mollusc species. It seems obvious, however, that
at least some of the "Senegalian" invaders could in fact survive the Würm glacial.
There is alm ost no proven case in which a faunal addition from the nearby
Red Sea occurred during the whole Pleistocene. If there were such immigrants,
they left no traces in the fossil record. The chronically impoverished Eastern
Mediterranean received its faunal supply exdusively from the west. The highest
elevation on the Isthmus of Suez is only 23 m but one cannot exclude eustatic
situations in which the Mediterranean communicated with the Red Sea. High
shores at such altitudes are known both from Egypt and from the Lebanon.
Fluviatile terraces of the Nile also indicate high Mediterranean levels. It will be
necessary therefore to take a doser look at the Pleistocene of the Isthmus of Suez
in order to und erstand why there is no sign of an interchange between the two
seas at high eustatic levels.
To conclude this chapter, however, emphasis must be laid on the fact that the
"Lessepsian" period of the Mediterranean Quaternary-a period beginning with
the opening of the Suez Canal-is the first and only phase in the whole PlioPleistocene complex where a massive faunal inflow from the Indo-Pacific occurred. The 45 1 species ofmolluscs which have already invaded the Eastem Mediterranean can give us a measure of the geological significance of this man-made
dispersal event. Future geologists might look at it one day as areversal of a basic
paleozoogeographic pattern perhaps as old as the whole of the Neogene Period,
spanning not less than some 20 million years.
1.3 The Pleistocene of the Red Sea
The Red Sea, isolated from the Mediterranean at least since the earlier stages
ofthe Pliocene, had an equally agitated Pleistocene history-along different lines,
however.
The movements wh ich led to the opening of the Red Sea Rift were especially
active during the Pleistocene and for practical purposes they may be considered
as still continuing.
Friedman (1968) considers that along the Sinai coast of the Gulf of Aqaba
some minor tectonic movements occurred as late as 5000 years ago. A raised coral
reef near Elat was radiocarbon-dated to 4770± 140 years, (Friedman, 1968).
H urne (1916) described raised Pleistocene coral reefs at an altitude of 200 m-much
above any possible high eustatic terrace. The sequence of high and low eustatic
levels, which is such a useful tool for understanding the Pleistocene history in the
Mediterranean and elsewhere, is therefore of little use in the Red Sea. It can also
be assumed that in the Straits of Bab el Mandab, which connect the Red Sea to
the Indian Ocean, tectonic activity continued throughout the period and the
depth and width of the sill area also changed.
1 Note added in proof: More species are added to the-list by Barash,AI., Danin,Z.: Additions
to the knowledge of Indo-Pacific Molusca in the Mediterranean. Conchiglie, Milano
13 (5-6), 85-116 (1977).