Environmental Engineering Reference
In-Depth Information
What does this information mean in relation to the early (or later) Quaternary
history of Mediterranean mountains? The mountains themselves may have been di-
vested of evidence for such change due to the tremendous erosional power of a
succession of ice caps and glaciers but the climate reconstructions facilitated by
ocean-sediment data reveal that the lands around the Mediterranean Basin, includ-
ing the mountains, were susceptible to the global climatic cycles of the early (and
later) Quaternary ups and downs of ice sheets and glaciers. Just as glaciers/ice caps
waxed and waned, forest, steppe and even desert vegetation communities shifted
latitudinally and altitudinally and changed in relation to species composition in the
mountains. Such shifts may not have been uniform throughout the Mediterranean,
as reported by Meyers and Arnaboldi (2008), whose work on isotope signatures in
marine sediments suggests that wetter conditions, that is, warm stages, were more
strongly expressed in the eastern Mediterranean than in the western Mediterranean.
This trend may also indicate increased continentality during cold/ice stages in the
eastern Mediterranean mountains, that is, increased extension of glaciers.
1.8 to c. 1
×
10
6
years ago
The base of this Middle Quaternary stage is defined on the basis of the stratigraphy
at Vrica, Calabria, southern Italy. The sediments were deposited in deepwater and
include a claystone overlying a sapropel deposit; the junction is dated at 1.81
10
6
years ago and is the base of the Calabrian (Van Couvering, 2004; Gibbard
et al.,
2009). Marine sediment cores from the Mediterranean Basin provide the most com-
prehensive record of environmental change for this period because the record is con-
tinuous and not fragmented as is the case for that from terrestrial archives. In partic-
ular the oxygen-isotope stratigraphy and the fossil record provide important insights
into the patterns and characteristics of the many climatic cycles that dominated this
period. As Figure 2.1 shows, there are some 38 oxygen-isotope stages during this
period, which represent some 19 climatic cycles in c. 800 000 years. Although the
amplitude of many of these cycles was not sufficient to create glacial conditions,
repeated warming and cooling would have affected the land cover and ecosystem
dynamics throughout the Mediterranean Basin including mountain regions.
In terms of detail, pollen analytical evidence from Montalbano Jonico, in the
Lucania Basin on the northeastern edge of the Southern Apennines of Italy, re-
ported by Joannin
et al.
(2008), shows that during the period 1.25 to 0.90 million
years ago (oxygen-isotope stages 37 to 23) significant changes in plant community
composition occurred that were driven by climatic change, including variations in
precipitation as well as temperature, and changing sea-level. Such changes parallel
the oxygen-isotope stratigraphy recorded from the deep-water foraminifera
Glo-
bigerinoides ruber
and
Globigerina bulloides
, which are accepted indicators of sea
temperature, as recorded in core from the ODP site 967 shown in Figure 2.1. Joan-
nin
et al.
state that 'On the whole, the mesothermic vs. steppe [pollen] ratio and oxy-
gen isotopic compositions made on
Globigerina bulloides
are correlated .
×
Hence,
...
