Environmental Engineering Reference
In-Depth Information
Quaternary environmental
history
A.M. Mannion
2.1 Introduction
The uplands bordering the Mediterranean Sea (see Chapter 1, Figure 1.1) were
formed when sediments that accumulated in the ancient Tethys Ocean were sub-
ject to heat and pressure as the North African and Eurasian plates collided. This
occurred between 100 million and 60 million years ago leaving a shrunken Tethys,
namely the Mediterranean Sea, as configured today. Thereafter these uplands were
subject to plant and animal colonization including the newly evolved mammals and
angiosperms, soil formation, and denudation processes in the Tertiary. The warm
tropical/subtropical climate of the Tertiary gradually deteriorated, culminating with
the onset of glaciation in northern hemisphere, the first cold stage of the Quater-
nary, now redefined by the International Commission on Stratigraphy as commenc-
ing c. 2.6 million years ago (Gibbard et al., 2009). This climatically diverse period
was characterized by repeated cycles comprising cold and warm stages that, at their
extreme expression, were glacials and interglacials. In general during the early part
of the Quaternary, before 900 000 years ago, cold/glacial stages were roughly of the
same duration as warm/interglacial stages, but in the later part of the Quaternary
the cold/glacial stages were considerably longer than warm/interglacial stages and
all were characterized by internal climatic and ecosystem dynamism. Thus the last
2.6 million years has been a period of considerable environmental change on rel-
atively short geological timescales. This was a global phenomenon, with evidence
primarily derived from continental glacial and cave deposits, exposed and offshore
marine sediments and a few deep lake sediment sequences.
How Quaternary environmental change progressed in the Mediterranean moun-
tains is difficult to determine, not least because evidence of early cold/glacial stages
and warm/interglacial stages has been destroyed by the glaciers of the last ice
advance. Moreover, some regions have not been well investigated, for example
the Balkans, which creates spatial gaps in current knowledge. For most of the
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