Pleistocene Epoch
Overview
Topics covered in this section:
Introduction
The Pleistocene Epoch covers the timeframe between 1.6 million and
10,000 years ago. That's a very long epoch and a lot happened during
this period. It was a time during which ice sheets waxed and waned,
scraping across the continents in slow cadence.
One extremely significant event, the Brunhes/Matuyama Boundary (see
next section), saw the Earth tilt 180 degrees, effectively exchanging
the North and South Poles. Imagine the catastrophic events that
accompanied that flip!
An event that's equally important, at least to us humans, is that the
earliest humans arrived in Europe during the Pleistocene.
Brunhes/Matuyama Boundary
Geologists and climatologists study mud cores extracted from the ocean
floor to advance theories about prehistoric events. At 1200 cm in core
V20-238, scientists found a "boundary," which occurred when the North
and South Poles reversed their positions at 730,000 BP. In other words,
the Earth completely flipped over some 730,000 years ago.
This boundary, named the Brunhes/Matuyama Boundary, is regarded as
the division between the Lower and Middle Pleistocene.
Ice Ages
Four Ice Age Model
In 1909 Penck and Bruckner proposed the theory that there had been
four Ice Ages during the Pleistocene Epoch. However, recent mud cores
extracted from the ocean floor, plus studies involving the ratio of
Oxygen 16 versus Oxygen 18, tend to refute this "Four Ice Age" model.
Eight Ice Age Model
Using the Brunhes/Matuyama boundary (see above), there have been
eight full Ice Age cycles in the past 730,000 years. Initially, these
cycles were completed every 70,000 years or so.
But after 450,000 years ago, the cycles expanded for the last four
Ice Ages to a span of 100,000 years per cycle. This change in cycle
times may have had an immense impact on human settlement in Europe.
Recent Ice Age
Details about the landscape, as well as the flora and fauna, of Europe
are best known for the most recent Ice Age cycle:
- Last interglacial occured 130,000 years ago.
- Last glacial maximum occurred 18,000 years ago.
- Last glacial retreat occurred 10,000 years ago.
Using this last Ice Age as a rough guide to earlier cycles indicates
that more than half of the Ice Ages were neither full glacials nor
interglacials. Instead, the majority of time in each cycle was somewhere
in between.
We know that the extremes between the warm, forested interglacials
and the arid, cold full glacials were comparatively short-lived. In both
situations, herds of animals would have thrived, but particularly on the
open steppes and tundra. The prairie environment was ideal for herds of
bison, horse, red deer, and aurochs.
Following these herds would have been the abundant social carnivores
such as lion, wolf, hyena, and the huge cave bears.
The fauna existing during the last interglacial period included the
woodland rhino, the straight-tusked elephant, the hippo, and the fallow
deer. Then during the last glacial maximum, the fauna thinned out, being
pinched between two ice sheets.
The last glacial retreat ends the Paleolithic, an archaeological era,
and begins the Mesolithic, another archaeological era. We'll cover these
and other archaeological eras in more detail in a later document.
Arrival of Humans
The ebb and flow of environmental conditions roughly matches the ebb
and flow of human populations.
Hominid Dispersion
The earliest hominids have been found in east Africa and date to about
4 million years ago. And genetic evidence points to the separation of
hominids about a million years before that.
Between 2 and 4 million years ago, there is evidence suggesting a
radiation of hominids into eastern and southern Africa. This includes
the southern "ape men" and the australopithecines.
Then a little more than 1 million years ago, Homo erectus
appeared outside Africa. Their bones have been found in China and in
Southeast Asia (Java).
Mediterranean Pioneers
Pioneers from sub-Saharan Africa possibly reached the Mediterranean
region some time between 1 million and 700,000 years ago. There have been
Mediterranean claims of much older finds, dated between 1.0 and 1.8 million
years ago. However:
- Habitation objects do exist, but no hominid remains have been found
with the material.
- Only a few simple flakes and chopping tools similar to the stone
tools from the Olduvai Gorge in east Africa have been found.
- Finds don't correlate with the pattern of hominids reaching China
and Asia 1 million years ago.
It's hard to assign an age based solely on the outdated notion of a
gradual technological progression from simple to complex stone tools.
Some finds, for example, that are dated by multiple methods at 1.6
million years old (e.g., Acheulean), contain "advanced" hand axes and
cleavers, yet they precede later users of "primitive" stone tools.
European Pioneers
Isernia La Pineta, souteast of Rome, is presently the earliest European
site with abundant artifacts that have been cross-checked by different
methods of absolute dating. The site rests in a stratigraphic position
just beneath a volcanic horizon in which the Brunhes/Matuyama boundary
(see above) occurs. Potassium-Argon (K/Ar) dating confirms that the
site is at least 730,000 years old. Isernia is rich in fauna remains,
but like so many other extremely old sites, contains no hominid remains.
The earliest European sites that contain hominid remains are about
400,000 years old. These hominids are no longer Homo erectus,
but instead are Homo sapiens. A few of the better known sites
are Steinheim and Bilzingsleben in Germany, Petralona in Greece, and
Swanscombe in England. Skulls found at these sites range in age from
400,000 to 200,000 years ago.
Go Elsewhere
At this point, you have a couple of options:
Enjoy your stay and have a great day!
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