Environmental Engineering Reference
In-Depth Information
At the foot of the slopes, where the original plant cover has been destroyed
to make way for agropastoral activities, the soils are not well developed, and
Inceptisols prevail.
At the bottom of the valleys (e.g. the Lanaittu Valley), with the absence of
plant cover, soils are often immature (Entisols). In some places they show deep
profiles, which have allowed them to be used for agriculture.
In Sardinia the landscape morphology and climatic features make the island's
soils very fragile and sensitive to uses that do not take into account the soil's suit-
ability and limitations. In mountain areas the proper, balanced management of veg-
etation cover ensures the permanence of soil in situ, limiting the intensity of ero-
sional phenomena. Due to these environmental conditions the degradation of soils
is a problem of great concern on the island. Synthetically the Sardinian landforms
have been divided in this way: 18.5% mountainous areas, 67.9% hilly areas and
13.6% plain areas (Pracchi and Terrosu Asole, 1971). Almost everywhere the soil
moisture regime is of a xeric type (Raimondi
et al.,
1995). Plain areas apart, in the
remaining hilly and mountainous territory (86.4% of the total) soils belong mainly
to the Cambisols, Leptosols and Regosols. These areas are considered marginal for
most agricultural practices but have great importance for particular niche crops, and
for grazing and forestry.
4.8.2 Active volcanic landscapes
In Mediterranean Basin two main volcanic regions can be identified: the Aegean
and Italian. The Aegean region is characterized by reduced volcanic activity; it was
the scene of violent eruptions in the past, notably the one that nearly destroyed the
island of Santorini around 1400 BC, producing a large caldera. The Italian volcanic
region, which runs from Tuscany to Sicily and Pantelleria, is the largest volcanic
region in Europe and activity began here in the Pliocene (Woodward, 2009). Vol-
canic activity is still taking place, and we can distinguish three different types of
volcanism.
The first type is the explosive volcanism of the Aeolian Islands, represented by
two volcanoes, Stromboli and Vulcano, with different activities. The activity of
Stromboli is continuous, with weak explosions sometimes followed by intermittent
volcanic emissions. The activity of Vulcano develops instead into two stages: in
the first stage, due to its viscosity, the lava forms a dome in its crater of stagnation,
while in the second stage gas pressure underneath the dome causes it to explode and
shatter, allowing the next release of lava. Mount Etna in eastern Sicily is the highest
active volcano in Europe, and manifests the second type of volcanism, called ef-
fusive volcanism. The third kind of volcanic activity is the explosive volcanism of
the Southern Tyrrhenian associated with Campi Flegrei, Ischia and, above all, Vesu-
vius. Eruptions some 35 000 years ago gave rise to pyroclasts, which accumulated
