Italy has a complex geological history, characterised by marked environmental
and climatic changes. Around 100 million years ago the area now occupied by the
peninsula was covered by a tropical sea, the Tethys, which separated the
Euro-Asiatic and African continental plates. As the ocean
|Even though Italy is not a large country, it contains a great
variety of rock types. The Alps are largely formed of crystalline rocks,
such as granite and porphyry, and there are also sedimentary rocks, such
as limestone, dolomite and sandstone, in the eastern Alps. Sedimentary
rocks are also found throughout the Apennine range and on Sicily and
Sardinia. Crystalline and Volcanic rocks predominate in Sardinia.
Volcanic rocks are also common in Sicily and along the Tyrrhenian side
of the country, consistent with the volcanic activity in these parts of
Italy. The country's plains are mainly formed form mixed deposits of
gravel, sand and clay.
began to recede, various types of materials were deposited. including
limestones, dolomites and sandstones, as well as the extensive coral reefs to
the north-east from which the Dolomite mountain range was later formed.
Although earlier volcanic activity had resulted in the formation of the
original nucleus of the Alpine chain and other mountains farther south, the
crucial moment came around 40 million years ago when the African and European
continental plates collided. The collision forced the respective borders of the
plates and part of the bed of the Tethys to fold and rise up, beginning the
formation of the Alpine and Apennine chains. The Alps rose up relatively
quickly, at first forming an archipelago of tropical islands in the Tethys Sea.
The curvature of the Alpine and Apennine chains, as well as the transverse
orientation of the peninsula itself in the Mediterranean basin, reflect the
manner in which the continental plates collided. Both mountain chains underwent
significant erosion, resulting in huge deposits of sand, gravel and clay at
their feet and in part preparing the way for the development of land areas
including Tuscany. It is interesting to note that around six million years ago,
when both the Alps and the Apennine range were still submerged, the Straits of
Gibraltar closed up completely. As a result, the Mediterranean Sea, which was
all that remained of the vast Tethys, began to dry up. The Straits of Gibraltar
reopened some two million years ago, allowing the Atlantic Ocean to refill the
Mediterranean. Some scholars have suggested that this ancient geological event
could have given rise to the Atlantis myth, as well as the biblical story of
Noah and the great flood.
By around two million years ago, after the landscape has been shaped and
reshaped by the combined forces of continental plate movement and erosion, the
Italian peninsula had almost arrived at its present-day form. The level of the
sea continued to rise and fall with an alternation of ice ages and periods of
warm climate, until the end of the last ice age around 10,000 to 12,000 years
|Earthquakes & Volcanoes
|A fault line runs through the entire Italian peninsula - from
eastern Sicily, following the Apennine range up to the Alps of
Fruili-Venezia Giulia in the north-east of the country. It corresponds
to the collision point of the European and African continental plates
and subjects a good part of the country to seismic activity. Central and
southern Italy, including Sicily are occasionally rocked by sometimes
devastating earthquakes. The worst last century was in 1908, when
Messina and Reggio di Calabria were destroyed by a seaquake (an
earthquake originating under the sea floor) registering seven on the
Richter scale. Almost 86,000 people were killed by the quake and
subsequent tidal wave. In November 1980 an earthquake south-east of
Naples destroyed several villages and killed 2570 people. A more recent
earthquake in the Apennine range in September 1997, which affected
Umbria and Le Marche, killed 10 people and caused part of the vaulted
ceiling of the Basilica di San Francesco d'Assisi, in Assisi, to
collapse, destroying important frescos. In this century in April 2009,
an earthquake in L'Aquila killed 270 people.
Italy has six volcanoes:
Stromboli and Vulcano (on the Aeolian Islands), Vesuvius, the Campi
Flegrei and the island of Ischia (near Naples), and Etna (on Sicily).
Stomboli and Etna are among the world's most active volcanoes, while
Vesuvius has not erupted since 1944. However, this has become a source
of concern for scientists, who estimate that it should erupt every 30
years. Etna's most recent major eruption occurred in 2001, when
officials were forced to close a tourist area and scientific monitoring
station after lava flowed down the volcano's southern slopes.
Related volcanic activity produces thermal and mud springs, notably
at Viterbo in Lazio and on the Aeolian Islands. The Campi Flegrei near
Naples is an area of intense volcanic activity, which includes hot
springs, gas emissions and steam jets.