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GEOLOGY

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

Rock Varieties
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 ago.

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.

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