HOME 11/10/2003 |
A.M.T. Moore - Oxford University (1978)
Chapter 1 (Pages 21 - 25)
LATE PLEISTOCENE SUMMARY
Excerpts and Definitions and Addendums:
It will be helpful now to summarise the evidence discussed here in order to present an outline of the environment of the Levant in the late Pleistocene. We have established that during the last glaciation the level of the sea on the Levant coast dropped considerably. The temperature fell between 5 and 10 degrees Centigrade, the most likely estimate being about 6 or 7 degrees. This led to a lowering of the snowline and below that the treeline and altitudinal vegetation belts. The fall in temperature increased the effectiveness of precipitation which in its turn led to marked alterations in vegetation and lake levels; it does not appear however that there was much if any absolute increase in rainfall at this time. This together with the unequivocal evidence for an arid phase in the Levant towards the end of the Wurm glaciation contradicts the view expressed by some authorities (See Page 207 in *1 and Page 28 in *2 Below) that there was a distinct pluvial phase in the Near East corresponding to the Wurm/Wisconsin glaciation in northern latitudes.
For much of the last glaciation there were large lakes in the inland basins in the central and southern Levant because there was more available moisture in these regions than today. Moister conditions also prevailed in Egypt during this period. Apart from a lake in the Ghab section of the Rift Valley there do not seem to have been any large open bodies of water in Syria so there was not as much available moisture there as in the rest of the Levant. Early in the Wurm glaciation the vegetation was denser than it would be today without human interference. Tree cover extended throughout the upland zone behind the Levant coast. The slopes of the Lebanon Mountains and the lower Anti-Lebanon were clothed with mixed deciduous and coniferous forest. There was oak forest in Galilee and probably Judea while trees were found as far south as Sinai. Even the Jebels Alawiye and Zawiye carried more forest than would be possible today.
In northern Syria the forest thinned out in response to increased aridity and was largely replaced by steppe well before the middle of the Wurm; open forest and steppe were also characteristic of Macedonia for much of the last glaciatlon. The tree cover remained fairly dense in Lebanon and Palestine hovever until much later.
A marked change in the climate and environment of the Levant took place quite late in the Wurm. The Lisan, Jafr and Damascus basin lakes all shrank. The inception of this phase is approximately dated by C-14 determinations of lake sediments. These dates would suggest that the regression phase of these lakes began at approximately the same time about 20,000 to 18,000 BC.
The vegetation also changed about this time. The trees thinned out in the uplands and mountains and the steppe greatly expanded. In Galilee the oak forest was replaced by maquis. Although the Lebanon Mountains continued to be forested the tree cover was much reduced; im the Anti-Lebanon and around Damascus very few trees were to be found at all. The replacement of forest by steppe which had begun some time before in northern Syria went still further until only part of the Jebel Alawiye carried any tree cover. The whole Syrian plateau would have been intensely steppic and this zone would have extended as far south as Trans-Jordan. Similar steppic conditions characterised the Zagros at this time while steppe and open forest still constituted the vegetation in northern Greece.
Although there is disagreement among palynologists about the causes of these vegetation changes there seems little doubt that a reduction in the available moisture was responsible for the drop in lake level, the expansion of steppe and the reduction in tree cover. This stage coincided with the second severe cold phase of the Wurm in northern Europe (See Page 274 in *3 Below) and the temperature in the Levant would have been at its lowest during this period. The climate was therefore arid and relatively cool.
Towards the end of the last glaciation there was another change in environmental conditions throughout the Levant. The inland basin lakes expanded again though they did not reach their earlier Wurm high levels. The steppe retreated and there was an expansion of forest cover. Oak forest partly replaced maquis in northern Palestine while scattered evergreen, oak and olives grew in the Negev. The forests became much denser in the Lebanon Mountains and woodland with both cedar and deciduous species spread quite widely in the Anti-Lebanon. In northern Syria the forest exanded greatly over both the coastal mountains and the Jebel Zawiye. It was a mixed forest of oak, pistachio, olive and hornbeam with some cedar (See Page 746 in *4 Below).
During this period the vegetation of the Levant reached a particularly rich climax. As today there were three vegetation zones from the well-watered coast to the arid interior. In the coastal mountains and on the edge of the plateau to the east was a Mediterranean forest zone. Today species such as pine (Pinus brutia and Pinus halapensis), pistachio (Pistacia lentiscus), both deciduous and evergreen oak, oriental plane (Platanus orientalis) and juniper are characteristic of this zone (See Page 44 in *5 Below) but then it included several species typical of cooler conditions. This zone extended much further east and south than now. Beyond the Mediterranean forest lay the steppe zone (Irano-Turanian) with a rainfall of better than 300 and 150 milimetres (See *6 Below). Today this zone is composed principally of herbs and dwarf shrubs such as Ephedra, Noea, Haloxylon and Artemisia herba-alba but also pistachio (Pistacia atlantica) and jujube (See Page 47 in *5 Below); the plant remains from the Mesolithic settlement at Tell Abu Hureyra suggest that this site was richer in species then. An intermediate belt of open woodland would have lain between the Mediterranean and steppe zones like today (See *6 Below) but this belt may have been broader then. The third zone was the true desert (Saharo-Sindian or Saharo-Arabian), receivimg less than 150 milimetres rainfall a year and characterised by a very poor vegetation (ibid). This zone was much less extensive than today, probably occupying part of the Arabian interior and so only impinging on the south-eastern corner of the Levant.
Once again a change in the amount of moisture available seems to have been the principal cause of both the rise in lake levels and the spread of forest. This was entirely due to the increase in precipitation because we know from the deep-sea cores that the temperature worldwide had already begun to rise. This temperature rise or at least the effects of it seems to have taken place a little later in the Eastern Mediterranean and Red Sea as the cores from there do not indicate any significant warming much before 12,000 or 13,000 BP (See Page 326 in *7 Below). The presence of species such as silver lime in the hills around Damascus indicate that it was still relatively cool during this phase.
The date for the beginning of this moister phase is uncertain because the relevant C-14 dates from pollen spectra and sediments in the Levant occur either well before or sometime after its inception. A good estimate can hovever be made from data in neighbouring regions. The transition from zone X to zone Y in the pollen spectrum from Tenaghi Philippon is dated at 12,650 ± 200 B.C. GrN-4183 (See Page 523 in *8 Below), a date that fits well with C-14 determinations from several cores drilled in the area. A similar transition at Lake Zeribar is dated about 12,000 BC. In the Levant itself we know that the change took place after a date of 16,850 ± 195 BC Hv-1725 for the regression phase in the Huleh basin and a date of 17,040 +/- 520 BC for the same regression in the Damascus basin. The phase also began sometime before 9400 BC in the Ghab, a date estimated from a C-14 determination of 8,130 +/- 55 BC GrN-5810 for the transition from sub-zone Z1 to Z2 in the pollen spectrum (See Page 743 and 751ff in *4 Below). The rise in level of the Dead Sea is dated 7900 ± 150 BC and must have begun sometime before that. A fair estimate for the beginning of this phase in the Levant might be about 12,000 BC bearing in mind the dates from Tenaghi Philippon and Lake Zeribar but this may be in error by as much as two millennia.
Although the date for the beginning of this phase is so uncertain the phase itself is clearly contemporary with the Late Glacial in northern Europe (See Page 274 in *3 Below). This was a ccmplex period of alternate milder and colder phases. It is not surprising therefore if it is difficult to interpret the geomorphological and pollen data for this phase in the Levant. The actual changes which these data record need not have happened at exactly the same time so one should not necessarily expect to be able to give a single date for the inception of this phase .....
(Only References in English are Included)
(Only References in English are Included)
*1 The Pleistocene Paleo-Environments in Israel
*2 Lake Lisan the Pleistocene Precursor of the Dead Sea
*3 Environment and Archaeology: an Ecological
*4 A Late Quaternary Pollen Diagram From NW Syria
*5 Plant Life of Palestine 
*6 Vegetation of Israel and the Near East
*7 Evidence of Climatic Changes in Red Sea Cores
*8 Palynology of the First 30 Metres