Portugal is a state of southern Europe, whose territory, overlooking the Atlantic Ocean for about 850 km, occupies the western edge of the Iberian Peninsula. The Atlantic archipelagos of the Azores (➔ # 10132;) and Madeira (➔ # 10132;) join the metropolitan territory.
The geological structure of the Portugal follows the general one of the Iberian Peninsula: the prevailing rocks are the granite and metamorphic ones of the Precambrian and Paleozoic age, which constitute the base of the Meseta. Relatively recent volcanic formations are present between Sintra and Lisbon and in the Algarve. Exclusively sedimentary formations of a marine environment, mainly limestone, emerge in a rather limited band, which affects Extremadura and a smaller arc of the Algarve. The sedimentary rocks, of continental or marine origin, are also of Neogenic age, which with alluvial deposits, present in the Tagus and Sado valleys, emerge in a narrow coastal strip north of Capo Carvoeiro. These rock formations reacted in various ways to the stresses connected with the Hercynian and Alpine orogeny; in particular the Iberian Central System and its extension towards the north-west, or the massif extended from Galicia to the Duero, fractured giving rise to numerous raised and sunken blocks which gave rise to a very complicated relief.
● The eastern section of Portugal (Trás-os-Montes and Alentejo) is affected by the Meseta and the northern one by offshoots of the central Iberian mountain range (Serra da Estrela, 1993 m, highest elevation in the country). AO the relief drops into the Tagus-Sado basin. The orographic arc of Extremadura extends to the NE of Lisbon. The coasts are wide and flat in correspondence of the depressions, narrow until they disappear and high when the mountain spurs loom over the ocean; the only joints are given by the estuaries and the Ria de Aveiro.
Many rivers belong to Portugal only for a more or less long terminal stretch (they mostly originate in Spain, where they develop a large part of their course, while Mondego alone, with other minor ones, has the entire basin in the country) and the their direction is dictated by the arrangement of the reliefs. The absolute flows are modest, except for the Duero, whose basin almost totally embraces the northern Meseta, receives the conspicuous contribution of the tributaries of the Trás-os-Montes region and collects the waters from high rainfall reliefs (Cantabrian Mountains and of León). The flow rate of the Tagus, much lower (490 m 3/ s, against 660 of the Duero), benefits from the contribution of some tributaries (Jarama and Alberche), fed by the abundant waters of the central chain and from the fact that it flows in a low, relatively rainy valley. The poorest of the great Portuguese fluvial arteries is the Guadiana, due to the modest contributions of its tributaries that descend from reliefs with little rainfall and because it crosses vast regions of the semi-arid southern Meseta. The rivers of the northern Portugal are richer, among which the Minho stands out. The waterways all flow into the Atlantic with even deep estuaries on which port cities have often sprung up.
The astronomical and geographic position strictly condition the climate of Portugal. It is particularly affected by the Atlantic or Azores subtropical anticyclone, which establishes rather uniform weather conditions in summer (with clear skies, high temperatures and little humidity), and the cyclones which, N of this high pressure area, invade the Iberian Peninsula, causing unstable weather conditions in autumn and March-April, especially in the north-eastern region. From the thermal point of view it is the coastal strip, in contact with the ocean, which directly feels its beneficial influences, which sometimes penetrate deeply inland, as in the case of the Tago-Sado depression. Moving away from the Atlantic or in the presence of mountain barriers, the temperature decreases.
According to trackaah, the population of the Portugal in 2009 amounted to 10,707,924 residents (density of 115.8 residents / km 2), having registered a constant but modest growth between the mid-1990s and 2003 and then a slowdown. The low natural increase (with almost equal birth and death rates) has led to a sudden aging of the population. Since 2000, the members of the younger age groups (up to 14 years) have been overtaken by those of the older classes (over 65), but not uniformly throughout the Portugal: in the autonomous regions in the Azores and Madeira and in the Northern region, the index relating to the elderly is significantly lower than 100, while in the Central and Alentejo regions it is considerably higher (140 and 170 respectively). The positive migration rate contributed to the growth of the population up to 2003, which then decreased from that year onwards (from 0, 7% in 2002 to 0.3% in 2009). The migratory phenomenon in Portugal, compared to other countries of the European Union, remains however marginal, even if it is worth noting the transition from a country of strong emigration to a country of immigration. The foreign component of the resident population, excluding that of other European countries, shows a clear prevalence of individuals from Portuguese-speaking African countries (43.7% of the total). The most represented group is that of the former colony of shows a clear prevalence of individuals from Portuguese-speaking African countries (43.7% of the total). The most represented group is that of the former colony of shows a clear prevalence of individuals from Portuguese-speaking African countries (43.7% of the total). The most represented group is that of the former colony of Cape Verde (20.1%), followed by Angola (10%) and Guinea- Bissau (7.7%). The Brazilian component also assumes a certain importance, attracted by Portugal for its linguistic affinity. ● Still at the end of the 1990s, the urban population was estimated at 37% of the total, a figure probably lower than the reality, but which reflected a previous condition of rurality in Portuguese society. In 2008, the urbanization rate was closer to that of other European countries, standing at around 59%. The illiteracy rate, which, despite having halved during the 1990s, is still quite high (7.5%) still remains uneven compared to all the other states of the European Union.