Piotr asked
> Do you happen to know more about the dates you quote? Are they
radiocarbon? calibrated radiocarbon? other? AFAIK the beginning of
the Subboreal phase is dated at ca. 3830 BC in calendar-year terms
(based on calibrated radiocarbon datings = ca. 3150 BC uncalibrated).
In northern Europe the cooling was quite significant, with heavier
snowfalls in winter and the weather generally less stable than during
the Atlantic phase. Forests gradually gave way to forest-steppe with
numerous open grasslands, and whatever the role of anthropogenic
factors, climatic deterioration certainly accelerated the process of
deforestation.
There was a major period of upset climate in about 3,200 BC known as
the Piora oscillation, which marked the end of the Atlantic period
and the beginning of the Sub Boreal. This refers to an advance of
glaciers in Europe at the end of the Atlantic period. It was a
sharper oscillation twards cold climate conditions than any for
several thousand years previously. See Lamb (1985), p. 372 (H. H.
Lamb. Climatic History and the Future. Princeton Univ. Press, 1985.)
Also have a look at the site
http://www.stanford.edu/~meehan/donnellyr/paleo.html
which correlates sea level changes around the world with this
period. Despite its quirky nature, this site is very sound. These
dates are absolute as it related to Ice Cores, independently dated
shoreline varves and tree ring data at different places, and pluvials
in Arizona and other locaions. It is confirmed in Breton and San-
Francisco Bay shoreline studies, and studies of the Australian
Barrier Reef, Fao Island (Persian Gulf) and Bermuda. It appears from
tree ring studies that 3,200 is also the coldest year on record for
the developing study of Oak tree ring analysis (Belfast) (Graph f
shows the cold spike clearly just before the 3,150 event).
Graph c shows the levels of the Dead Sea which was some 300 feet
above its current level at that time. This correlates well with the
evidence of Lake Chad I mentioned before. The site quoted above
about salt deposits and wet periods leading to the storage of
sufficient water on land to cause sea levels to fall by as much as 4-
7 feet (2 metres) should also be taken into account here. Only in
this case we are talking of a 20 foot (5 metre) rise in Sea Level.
I feel on the basis of the evidence we have another huge volcanic
event, similar to Lake Taupo in 1200 CE which precipitated the Little
Ice Age, or like Lake Toba, 73,000 BCE that began the freeze down for
the anatomically modern humans to escape from Africa. Given the
depopulation of Aegean region mentioned by Mark it is possible that
the event took place on this plate boundary, but we cannot (yet)
say. One sight suggests that it is linked to a major weakening of
magnetic filed associated with this period (see
http://www.geocities.com/Yosemite/Canyon/1656/index.htm) due to a
small change in the oblateness of the earth. The author suggests an
association with major erruptions in the Kamchatka Peninsula at the
time (bit I have not been able to track down the evidence for this).
The flood of Utu Napishtim (on which the genesis account is based)
seems to have been related to the 3,200 BCE sea level change, (i.e.
Ur sands) in the following manner. The Karun river, responding to
the need to start building a new delta into the Persian Gulf, and
flowing across a very shallow plain, backed up, to discharge its
waters into lower Mespotamia circa 2,700 BCE (In the period of EDI
associated with the hegemony of Sharrupak). Thus we are beginning to
have detailed evidence of the Biblical deluge as not one event, but a
number. Like what happens in Oral Traditions, events of a single
nature, after many tellings tend to tellescope into a single "big"
event.
In any case there is a major revision of Human History going on
associated with a detailed understanding of past climates. Herodotus
is clear in his associations of mentions of various famines in
history and the effects they have in the movement of people (eg. with
Tyrrhenos son of Atys, in his movement from Lydia to Etruria). The
Sea peoples aere generally associated with the climatic rainfall
degrease in the Eastern Mediterranean circa 1,200 - 1,100 BCE. This
lead to a huge depopulation of the Aegean-Anatolian area, which only
recovered circa 800 BCE with the recovery of Lydia and Phrygia.
There was also another huge climatic event about 6,000 - 5,500 BCE,
which saw the "Sahara pump" working yet again, to push the Semitic
Afro-Asiatic peoples across from the Eastern desert of Egypt into the
Sinai and Palestine where they took over from the Natufian PPNB
culture in southern Palestine.
Generally what the evidence is showing is that warm periods lead to a
movement north (hence my arguments with Glen), whilst colder periods
lead to movements to the south. Thus the movement of the Karasuk
people from the Eurasian steppe to China, Guillaume, that I mentioned
before as a possible ST movement. It would seem that 3,150 BCE was a
cold snap which would have begun a movement south and west from the
Steppes (possibly the break up of PIE?).
Independently of "warm-cooling" cycles, there is the independently
observed "wet-dry" phases, which are associated with a shift from
agriculture to nomadic pastoralism and back again. It is no wonder
that the dry phase on the steppe is associated with the spread of the
Iranian nomads from Hungary to Mongolia, and the appearance of the
feared Scythians into the Middle East.
We are seeing a much more nuanced understanding of climates than that
shown by "glacial" versus "interglacial", where dry periods in one
location are associated with wet phases elsewhere. Generally for
instance, the Atlantic phase saw Mediterranean dry summers extending
as far north as southern Britain, and semi-arid conditions also
moving north with the Sahel having increased rainfall. The Piora
oscillation saw the reverse, with very wet Atlantic conditions in
Palestine (hence the filling of the Dead Sea), Mediterranean winter
rains moving south, and the empying of Lake Chad.
Such things as this have a huge effect upon the spread and
distribution of languages. For instance the drying of Lake Chad saw
the spread of Nilo Saharan languages confined to their present
limited ranges (Niger River Bend, Nile Valley and South Western
Sahara). It had previously been associated with the catfish peoples
of the southern Sahara and their wavy lined pottery.
Hope this helps
Regards
John