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From: "lkramsey" <>
Subject: [DNA] Out of Africa
Date: Wed, 18 Apr 2012 12:13:01 -0400


John,



The following is taking directly from Cunliffe relative to the earliest
arrivals to prehistory Europe.



"In Europe the earliest site with abundant artifacts and cross-checked by
different methods of absolute dating is Isernia La Pineta south-east of
Rome. The importance of this site rests in its stratigraphic position just
beneath a volcanic horizon in which the Brunhes/Matuyama boundary occurs and
which K/Ar dating confirms as at least 730,000 years old. The site is rich
in fauna with the remains of extinct bison accumulated in stream deposits.
Among these bones are many thousand flakes and pebble tools. Unfortunately
there are no hominid remains, but on this evidence, which compares with the
chronological estimates from China and Java, the pioneers from sub-Saharan
Africa possibly reached the Mediterranean province between one million and
700,000 years ago. The lakeside site of Soleihac in the Auvergne, where a
few flakes and pebble tools have been dated to 900,000 years old, provides a
glimpse of the fragmentary evidence that such pioneers would have left."



The (K/Ar) dating for the Brunhes/Matuyama boundary at 73,000 years ago is
the measurement of the decay by isotopic decay between potassium and argon.
This is a significant date for European prehistory between the Lower and
Middle Pleistocene.



Also, the four-Ice-Age system of the Pleistocene created in 1909 has been
found to be grossly inadequate. The current pattern of the Ice Ages comes
from the sediments on the bottom of the ocean floor, where the tiny
skeletons of marine creatures, foraminifera when alive lived at its surface.
Their skeletons consist of calcium carbonate which absorbs the oxygen
isotopes present in sea water. This sponge effect has proved very useful in
establishing the number and rhythms of the Ice Ages. What this has
demonstrated is the number of repeated interglacial/glacial cycles in a
"continuous" sequence.



The major breakthrough with the deep-sea Ice Age record is that it can be
dated. "At 1200 centimeters in core V28-238 the sediments show a magnetic
reversal when the North and South Poles adopted their present positions.
Before they were completely reversed. With this date fixed in the core the
ages of each cycle can be determined by dividing depth into age. In the
past 730,000 years there have been eight full cycles. Initially these were
completed every 70,000 years but after 450,000 years ago they extend to a
span of 100,000 for the last four. This change in the duration of cycles
may have had a major impact on settlement in the Continent."



Lee





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