Even if it is not very extensive,theItalian territory is distinguished by the considerable variety of its substratum rocks. The Alps are largely formed from crystalline rocks (granites, gneisses, mica-schists, porphyries, etc.) but there are also sedimentary rocks (limestones, dolomites and sandstones) that are widespread in the eastern sector and the pre-Alpine belt. Sedimentary rocks are also prevalent throughout the Apennines (limestones, dolomites, sandstones, clays, marls, etc.), including Sicily, and are found in Sardinia too, where crystalline and volcanic rocks predominate. There latter (formed from ancient and recent lava and tufa) also appear in Sicily and along the peninsula's Tyrrhenian margin (where there is a considerable concentration of volcanic phenomena, in part still active) as well as in the Alps. Finally, the flat areas, including the great Po-Venetian Plain, are basically formed of mixed deposits that are mainly fluvial in origin (conglomerates, gravels, sands, clays). The great variety of rock types characterizing the Italian framework is mainly the result of a complex geological past, distinguished by marked environmental alternations - now marine, now continental - as well as frequent changes in climatic conditions. Furthermore, even if present mountain forms are considered to be rather recent, Italy does contain extremely old rock formations. Some of the metamorphic outcrops in the Alpine arc and in the Sardinian-Corsican and Calabrian-Peloritan massifs were formed before the Palaeozoic era, that is more than 600 million years ago, and therefore do not contain significant traces of organisms. During the Palaeozic era (lasting from circa 570 to 230 million years ago) the area now occupied by Italy was largely covered by a tropical sea (called Tethys by geologists) from which must have emerged some mountain folds, as those of the Caledonian period, begun some 500 million years ago and whose traces remain in southwestern Sardinia (Iglesiente and Sulcis). The next mountain building period, the Hercynian, occurred during the last 100 million years of the Palaeozoic era and was accompanied by considerable volcanic activity. This provoked the formation of the original nucleus of the Alpine chain together with the emergence of the Calabrian-Peloritan mountains (Aspromonte and Sila in Calabria and Peloritan in Sicily) and the Sardinian-Corsican massif. The volcanic activity of this period also affected the Alpine arc (porphyry effusions in the Adige Valley), as well as in the northern Apennines (Garfagnana and Apuan Alps) and Sardinia and Corsica. Following the Hercynian orogenesis, the mountains formed by it were subject to intense erosion. Thus at the end of the Palaeozoic era there emerged from the waters of the Tethys (the extensive oceanic basin separating the Euro-Asiatic continental plate from the African) the remains of the palaeo-Alpine chain, part of the northern section of the peninsula - probably connected with the Sardinian-Corsican massif, and, further south, the other great island fold of the Calabrian-Peloritan massif. During the course of the succeeding Mesozoic era, lasting for over 160 million years, almost all the present area of Italy remained covered by a large marine basin on whose bottom (which varied considerably in depth) was deposited on different occasions material of various types. This was to produce, following a process of compaction and orogenesis, disparate rock formations: limestones, dolomites, sandstones, marls, etc. In particular, in the northeastern area there formed extensive coralline reefs from which the present Dolomites are derived. Towards the end ot the Mesozoic era the progressive moving together of the African and European continental plates reduced their common marine space and caused a folding of their respective margins and part of the bed of the Tethys. This was to produce the Alpine and Apennine chains whose curvature reflects the anticlockwise movement of the contact line between Europe and Africa produced by the particular forces of their respective plates. Their collision took place some 40 million years ago (between the Eocene and Oligocene periods) in the first-half of the Cenozoic era, which is considered to have lasted from circa 65 million to 2 million years ago. lc>The formation of the Alps and the Apennines continued throughout the Cenozoic, slackening in the succeeding Miocene and Pliocene periods in which however some uplifting continued. This was accompanied by intense volcanic activity that has left traces in the Lessini Mts. (Venetian pre-Alps), Euganean Hills, Sardinia, Tuscany and Sicily (Iblei Mts.). Already, however, during the Miocene period erosion had considerably increased on the Alpine and Apennine peaks and this also continued in the Pliocene period, resulting in the depositing at the feet of the chains of huge deposits of sand, gravel and clay. There then followed a phase of general increased marine predominance, lasting a good part of the Miocene and all the Pliocene. At the end of this latter period, circa 1.8-2 million years ago, with the withdrawal of the sea and the filling up of the great Po depression the shape of the present-day Italian region and particularly the peninsula and islands began to gradually appear. The Neozoic era, which is still in progress, was characterized in its early part (corresponding to the Pleistocene period) by alternating warm and cold climatic phases, which resulted on several occasions in the expansion and retraction of the Alpine and Apennine glaciers with a consequent alteration in sea level. The last glaciation ended circa 10-12 thousand years ago, giving way to the current Holocene period characterized in Italy by temperate climatic conditions. During the Neozoic era, usually called the Quaternary, volcanic activity has re-occurred very intensely especially on the Tyrrhenian side. Surface erosion followed the relief modelling, filling in with detritus the internal Apennine depressions previously occupied by lakes (Val d'Arno, Val Tiberina, etc.) and also forming the plains at the edges of the peninsula and islands. At the same time, while our present flora and fauna were evolving, there appeared the first known representatives of the human species in Italy, whose traces have recently been found near Isernia (La Pineta) and date to some 730,000 years ago.
The complexity of its geological history combined with the wide variety of its substratum rock types, often dislocated by numerous fault-lines and folding of the rocky strata by orogenic forces, have contributed to Italy's extremely diverse morphology. Less than a quarter (23%) of its total territory is formed by plains, while mountainous areas occupy over a third of its surface (35%). Finally, over two-fifths (42%) consists of hill zones. Italy's maximum height above sea level corresponds with the summit of Mt. Bianco, 4,810 m., on the border with France. The far eastern section of the Po Plain has in contrast some zones slightly below sea level, which are generally subject to subsidence phenomena. However, physically, the Italian territory can be considered to consist of the following regional units, characterized by a certain morphological similarity and at times also climatic: the Alpine system and Po-Venetian Plain in the continental section; the Apennine system and anti-Apennine reliefs in the peninsula section; and the large islands of Sicily and Sardinia.
The Alps
Almost the whole southern side of this great mountainous system belongs to
Italy, covering as it does a length of circa 110 km from the mouth of the
Rhône to the mid-Danube plains and varying in width from circa 150
to 250 km. This southern side contains many longitudinal (Valle d'Aosta,
Valtellina, Val Venosta and Val Pusteria) and transversal valleys (Val di
Susa, Val d'Ossola, Val Camonica and Valle dell'Adige). It can be divided
in three sectors: western, central and eastern Alps. The first two of mainly
crystalline rocks and the third of sedimentary rocks. Their traditional groupings
are still in use: western sector of Ligurian, Maritime, Cottian and Graian
Alps; central sector of Pennine, Lepontine and Rhaetian Alps; and eastern
sector of Adige, Carnic and Julian Alps. The first two groups contain the
highest peaks, often exceeding 4,000 m. (Gran Paradiso, Mont Blanc, Cervino,
Rosa and Bernina). The pre-Alpine belt is mainly formed of sedimentary rocks.
It stretches from the mouth of the Valle d'Aosta to the Valle dell'Isonzo
and is particularly disjointed, especially in two zones: the Lombard pre-Alps,
where the landscape of valleys is enlivened by large glacially excavated
lakes (Orta, Maggiore, Lugano, Como, Iseo and Garda); and the Venetian pre-Alps,
which contain numerous plateaux (Lessini, Sette Comuni and Cansiglio).
The Po-Venetian Plain
This is the principal Italian plain, extending for circa 42 sq km to the
south of the Alpine arc and having its other border with the northern Apennines
and the Adriatic where it merges into a coast that is low and sandy on the
Romagna shore and ringed by lagoons on the Venetian shore. The Po River cuts
across the centre of the plain and, over the past two thousand years, has
created a huge delta on the edge of the Adriatic Sea. In this it has been
assisted by many Alpine and Apennine tributaries, as well as by other
watercourses descending directly to the sea from the Venetian pre-Alps (Adige,
Brenta, Piave, Tagliamento and Isonzo) and the northern Apennines (Reno,
Lamone and Marecchia). The Po-Venetian Plain has a mean altitude of circa
50 m, while in the marginal belt at the foot of the pre-Alps and the Alps
it exceeds 200 m. This is the point at which it is possible to distinguish
a high (gravel and sand) from a low (mainly mud and clay) plain, separated
by a row of springs that have had an important influence in the development
of the plain's agricultural economy (cultivation of the rice fields, water
etc.). This plain also has an extremely important economic and social role.
Though it forms only a seventh part of the national territory it contains
about a third of the Italian population.
The Apennines
The Apennine range extends for over 1,200 km from the Colle di Cadibona (touching
on the Ligurian Alps) to the extreme south of Calabria and then includes
all the north Sicilian mountains. It forms the mountain backbone of the Italian
peninsula, unfolding in an extensive concave chain that opens towards the
Tyrrhenian Sea. Sometimes its mountains run parallel and sometimes they seem
detached in isolated groups, usually separated by wide valley and basins
(Valdarno, Val Tiberina, Valle del Volturno, Vallo di Diano, Piana del Fucino,
etc.). Furthermore, these alternate with numerous transversal valleys that
often narrow into gorges. As with the Alps so with the Apennines, three sectors
can be distinguished: a northern one of largely sandstones, marls and clays,
covering Liguria, Tuscany and Emilia; a central one essentially of limestones,
covering Umbria-Marches and Latium-Abruzzo; and, finally, a southern one
of mixed rock types, covering Campania, Basilicata and Calabria. Along both
edges of the peninsula extensive depressions separate the Apennine chains
from isolated reliefs. These are usually given the name Antiapennine: Tuscan
Antiapennine, with the Monti del Chianti, Amiata and Colline Metallifere;
Latio-Campania Antiapennine, with its volcanic belt running from Cimini Mounts
to Roccamonfina and Vesuvio; and Puglia">Apulian Antiapennine, with the
Gargano, Murge and Salentina Peninsula. In Sicily, the Iblei Mounts can be
considered to fulfil an Antiapennine position. Adjacent to the Antiapennine
reliefs and generally opening on to the sea there are fairly extensive river
plains. On the Tyrrhenian side of the Italian peninsula these consist mainly
of the lower Valdarno, the Ombrone section of the Maremma, the Pontine Marshes
and the Campanian plains of the Garigliano, Volturno and Sele. On the Adriatic
side, the largest river plains are those of the Tavoliere in Puglia and the
Piana di Sibari in Calabria. On the islands there are the plain of Catania
in Sicily and that of the Campidano in Sardinia.
The islands
Besides the reliefs already mentioned, Sicily also has Etna, Italy's major
active volcano, and a large and undulating inland plateau. The latter is
mainly formed of chalk rocks and rich sulphur deposits that with the heights
of the Monti Erei connect the Iblei to the northern chains (Madonie, Nebrodi,
etc.). Sardinia in its turn is characterized by reliefs of no great height,
mainly formed from crystalline (granites) and volcanic (trachytes and basalts)
rocks. On the western side extend large flat areas like the previously mentioned
Campidano, limited by the gulfs of Cagliari and Oristano. The minor island
groups are mainly present in the Tyrrhenian Sea, such as: the Tuscan archipelago
(290 sq km), dividing the Ligurian and north Tyrrhenian seas; the Campanian
archipelago (71 sq km) with the Pontine Isles; Ustica (8.6 sq km); Aeolian
Isles (115 sq km); Egadi Isles (38 sq km); Pantelleria (83 sq km) and the
Pelagian Isles (25.5 sq km) in the Channel of Sicily. In the Adriatic, besides
the various low and sandy islands of the Po delta and Venetian lagoon, there
emerges the Tremiti archipelago (3 sq km) to the north of the Gargano. Finally,
there are numerous islands along the coasts of Sardinia (Asinara, La Maddalena,
Caprera, San Pietro, Sant'Antioco, etc.,), mainly due to the sinking and
subsequent submersion of the margins of this major Tyrrhenian island.
The coastline
The complexity of the peninsula's relief is echoed in the diversity of its
coastal profile. Along the low and sandy Adriatic shores this is generally
rectilinear, with the exceptions of the bulge of the Po delta and of the
two rocky promontories of the Conero and Gargano. The Ionian and Tyrrhenian
shores are very different, their extensive sandy curves, corresponding to
the edges of the coastal plains, alternating with high rocky coasts or steep
promontories like those of Piombino, Argentario, Circeo, the Sorrento Peninsula,
etc. The coasts of Sicily and Sardinia present a similar morphological picture,
the latter having frequent rias or deep inlets resulting from the sinking
of long stretches of the eastern coast.
Despite its geographical position at the centre of the temperate zone, Italy has rather variable climatic characteristics. This is due to the presence of the Mediterranean, whose warm waters mitigate thermal extremes, and the Alpine arc, which forms a barrier against the cold north winds. Furthermore, Italy is subject to both wet and moderate atmospheric currents from the Atlantic Ocean and dry and cold ones from eastern Europe. The Apennine chain too, confronting the wet winds from the Tyrrhenian, causes considerable climatic differences between the opposite sides of the peninsula. The differences in temperature between the winter and summer months are more marked in the northern regions than in the south and along the coasts. The mean temperatures for the month of January in the Po Plain fluctuate around zero, while in the Alpine valleys the thermometer can drop to -20º and snow can remain on the ground for many weeks. In the southern regions, instead, the mean temperatures for January remain around 10º, with the exception of the inland mountainous zones. Mean summer temperatures throughout all Italy rise to 24º-25º for July, only being lower in the highest zones. Rainfall distribution also varies considerably, due to the influence of both mountains and prevailing winds. The highest quantities are registered in the Alpine arc (over 3,000 mm pa in the Lepontine and Julian Alps) and on the Apennines (over 3,000 mm pa in the Apuan Alps). The plains, however, including that of the Po, receive scarce precipitation. Generally it is less than 800-900 mm pa but in the southern regions (Tavoliere and southern Sicily) it falls below 600 mm pa. The great internal Alpine valleys and the coastal plains of the Tyrrhenian (Maremma) and Sardinia also receive little rain. Altogether, six large climatic regions can be distinguished, mainly characterized by mountain influence. 1) An Alpine region, strongly influenced by altitude, with long cold winters and short cool summers having an elevated day-time temperature range; precipitation is more intense in the summer months, especially in the pre-Alpine belt. 2) A Po region, with continental conditions, consisting of cold and often snowy winters and warm and sultry summers; precipitation is greatest in the spring and autumn months; the climate becomes milder, however, around the pre-Alpine lakes; fog is frequent, due to the wetness of the land. 3) An Adriatic region, whose sea has lit tle influence due to the inability of its shallow waters to trap the summer heat; consequently the climate has a continental character, with its winters being dominated by cold north-east winds (bora). 4) An Apennine region, also with continental tendencies and cold snowy winters; precipitation is more intense on the Tyrrhenian slopes and is abundant in all seasons apart from the summer. 5) A Ligurian-Tyrrhenian region, with a maritime climate and heavy and frequent precipitation, which is less in the summer and distributed irregularly; the winters are cool and the annual temperature range narrow. 6) A Mediterranean region, also with a limited annual temperature range; precipitation is frequent, especially in winter, and the summers are hot and dry. The interior and mountain zones of the islands and Calabria also have an Apennine type climate due to the altitude.
The characteristics of the Italian water network are closely associated with morphological and climatic conditions. There are only a few tens of watercourses longer than 100 km, though the Po, which is also the longest of them all (652 km) has a rainwater basin almost equal to a fourth of the national territory (74,970 sq km). Other important rivers are the Adige and Piave, descending from the Alps and flowing from the north into the Po, and the Arno and Tiber, flowing through central Italy into the Tyrrhenian. The other main tributaries of the Po are the Ticino, Adda and Oglio, arising in the Alps, the Tanaro, from the Apennines, and the Reno too, though it has its mouth to the south of the Po delta. The rivers running down the Tyrrhenian slopes of the peninsula are usually longe than those of the Adriatic, because of the Apennine watershed being further to the east. The Italian waterways are little used for transport due to their rather limited and variable flow. In fact the Alpine rivers have a cycle conditioned by the winter snow cover, being high in the summer and low in the winter; while the pre-Alpine and northern Apennine source rivers are mainly rain-fed and are only full in spring and autumn. Consequently, the cycle of the Po River is the most regular and therefore best suited to navigation. The other rivers of the peninsula and islands are heavily influenced by climatic conditions, being full in winter and empty in summer. In the latter case it is not unusual for the bed to remain completely dry, as in the case of the typical fiumare in Calabria and Sicily. Italy is fairly well supplied with lakes, having several thousand natural and artificial basins of different sizes and origins. The largest and deepest occupy the bottom of the great pre-Alpine valleys at their junction with the Po Plain (from Lake Orta to Lake Garda, which is the largest of all, while Lake Como is the deepest) and they were all excavated by Pleistocene glaciers. Also along the Apennine spine there are fairly frequent large lakes, such as Trasimeno the remains of an older lake that together with others occupied the bottom of the internal basins of the peninsula. The numerous small lakes scattered inside the spent craters of Latium and Campania are volcanic in origin. The coastal plains of the Tyrrhenian, Adriatic and large islands contain basins that are sometimes extensive and derived from lagoons. Furthermore, the Italian Alpine slopes, above 2,800 m., contain about a thousand glaciers. Some of these are of a considerable size, such as the Miage Glacier, which is some 10 km long and descends the southern slope of Mont Blanc in Valle d'Aosta. The glaciers are especially important for their function as water reserves, providing as they do a constant supply for the Alpine rivers. The central Apennines also have a small glacier, under the northern walls of the Corno Grande (Gran Sasso). Finally, Italy's water system is completed by the many underground water bearing strata of the numerous limestone karst massifs in the pre-Alps and Apennines. These produce springs bearing a considerable volume (as that of the Peschiera in Latium or the Sele in Campania, etc.). In addition, there are those reaching to varying depths under the Po Plain and the other alluvial plains.
With its extension from southern Europe towards Africa, the Italian peninsula almost divides the Mediterranean in two separate basins. Leaving aside the Strait of Messina, the shortest distance between Sicily and Africa (NE Tunisia) is circa 140 km, reduced to 70 km if it is measured from the island of Pantelleria. In this part of the sea (Channel of Sicily) the depth does not exceed 500 m. Furthermore, the eastern Mediterranean section, known as the Sea of Sicily and from which emerge the Maltese Islands, the Pelagian and Pantelleria, rarely exceeds a depth of 1,500 m. Considerably deeper, on the other hand, is the Ionian Sea. This extends eastwards from Sicily and Calabria and southwards from the Salentina Peninsula, touching on the 4,000 m isobath. Equally deep is the Tyrrhenian Sea, within the triangle formed by Corsica and Sardinia, Sicily and the Italian peninsula. At its centre it often exceeds a depth of 3,500 m. A narrow channel (the Canale di Corsica) separates it, to the north, from the Ligurian Sea. This latter exceeds a depth of 2,000 m in its western section corresponding to the Riviera di Ponente. The shallowest of the Italian seas is the Adriatic, which up to the level of Ancona does not exceed 80 m and only at Pescara does it decend below 200 m; off the coast of Puglia, however, it exceeds a depth of 1,200 m. Finally, in the area of the Strait of Otranto the two shores of the Adriatic draw close together and here the Italian and Albanian coasts are only 75 km apart. As for the rest of the Mediterranean, the surface temperature of the Italian seas is on average rather high. In the northern Tyrrhenian, the Sea of Sicily, Ionian and southern Adriatic it is circa 13º; in the Ligurian Sea circa 12º; in the southern Tyrrhenian circa 14º; but in the northern Adriatic, because of the shallowness of the waters, it drops to 9º. The quality of the water is also rather elevated, reaching over 38 per mille in the southernmost zones and the Sea of Sardinia, while being slightly less (33 per mille) in the northern Adriatic. The Adriatic is also subject to tides (which can range over about a meter) and these can sometimes create problems, such as the high waters in Venice and the lagoon.
Man's intense exploitation over many thousands of years has greatly altered the original condition of the vegetation cover, this is true also for the high mountain zones of the Alps and Apennines, which were subject to systematic deforestation until the end of the last century. Despite massive attempts to protect the mountains from the beginning of this century, many of Italy's mountain regions still remain without tree cover and are therefore susceptible to hydrogeological disaster, especially in the zones with particularly unstable rock types. At the present time little more than a fifth (21.2%) of Italy is covered by trees, which altogether occupy an area of circa 64 sq km. In the strictly floral category, the region of Italy unites Mediterranean and central European species. When these are combined with morphological and altimetrical influences a varied floral landscape results that is more dependant on climatic conditions than soil types. Thus it is possible to identify at least four principal floral regions. 1) An Alpine region, divided into bands according to height, with oaks and other broad-leaved trees prevailing in the lower areas and valley bottoms, followed up to circa 1,000 m by chestnuts and then beeches followed still higher up, but not beyond 2,000 m., by a mixture of needle-leaved trees (firs, larches and Scotch pines); the summit areas are dominated by meadows and pastures together with shrub vegetation (rhododendrons and dwarf pines) or, on the margins of permanent snow (circa 2,400-2,800 m.), by Alpine tundra with mosses and lichens. 2) An Apennine region, similar in character and sequence to the Alpine but with the presence of temperate species in the valley bottoms and a lesser spread of conifers in the upper levels. 3) A Po region, dominated by broad-leaved trees (willows, alders, poplars and oaks), which still form small woods but only along the river banks, while on the upper plain survive extensive stretches of the original heath with American acacias, heathers and brooms. 4) A Mediterranean region, covering the Ligurian and Tyrrhenian coasts as well as those of the central and southern Adriatic and the islands, dominated by a mixture of maritime pine and evergreen macchie (with olives, cypresses, corks, etc.) derived from the spoiliation of the original ilex groves.
At present Italy has five national parks. The first of these, the Parco Nazionale del Gran Paradiso, extending over 70,000 hectares, was established in 1922, closely followed by that of Abruzzo (40,000 hectares) in 1923. In 1934 and 1935 the parks of Circeo (8,400 hectares) and Stelvio (137,000 hectars) were respectively established; and, finally, in 1968 that of Calabria (18,000 hectares). In addition, the Ministero dell'Agricoltura e Foreste directly manages a certain number of nature reserves of different types, which together total slightly more than 100,000 hectares. Nature parks and protected areas are also controlled by some regional administrations, while there are numerous proposals for a further increase in areas to be protected. Among these, the wetlands are of considerable importance, being largely of hydrogeological and faunal interest and extending for slightly less than 50 000 hectares. Beyond specific environmental and naturalistic aims, the national parks and protected areas are intended to safeguard the typical Italian fauna. The large wild game, which has long been heavily hunted, has almost disappeared: the brown bear only survives in the Trentino and Abruzzo, while the wolf has now retreated to the remotest zones of the centralsouthern Apennines. However, the Mediterranean macchia contains a fair number of wild boar and the national parks offer refuge to ibex, chamois, red deer, etc. Small rodents are still numerous (hare, squirrel and dormouse), as well as other small mammals (fox, wild cat, etc.) and reptiles and birds. Among the birds of prey, the hawk is still quite common but the eagle is increasing in rarity. The variety of fish, both in fresh and salt water, is considerable, although, in both cases, seriously threatened by pollution.