The Strait of Gibraltar didn't exist yet, but several small straits replaced it. The first Hominids in Africa appeared more or less 6 million years ago. At that time, the ancestors of many animals like Felids, Canids or Rodents were also already roaming on the earth's surface.
It is around that time that the water coming from the Ocean into the Sea was totally "cut off" or nearly so. This resulted from different factors, amongst which the movement of tectonic plates for a definition, see another article on our website: "What if mountains came out of the Mediterranean Sea? Little by little, the Mediterranean totally dried up, just as if we left a full saucepan of salt water to evaporate on the fire: it would leave only a thin crust of salt at the bottom.
This is exactly what happened, and important layers of salt piled up at the bottom of the Mediterranean. From time to time, some water would succeed to come through and would fill in, for a while, the bottom of the basin before evaporating. The Mediterranean had turned into a vast salt desert. This situation lasted for nearly ' years. This is why, in some places under the bottom of the sea, you can find layers of salt which are more than meters thick.
Finally, around 5. Water from the ocean arrived into the Mediterranean basin, creating a gigantic waterfall, with a flow rate a thousand times bigger than the flow rate of the Niagara falls!
And this is how, only a few centuries later which is a really short time on the geological scale , the Mediterranean Sea was normally filled again. Subscribe to our mailing list to get updates about our educational projects and free educational resources. This is a low trafic mailing list. Jump to content. As such, it has two characteristics.
First, its strategic relevance to outside powers such as the United States depends on whether they deem European political dynamics of vital interest. If continental Europe and to a lesser degree the Middle East loses geopolitical appeal, then the Mediterranean is of little significance. Second, the stability of the Mediterranean can be guaranteed only when one power or friendly powers controls access to it as well as its circumference; when its shores are under the sway of rival powers, it becomes an unstable frontier sea.
In brief, the importance of the Mediterranean Sea is conditional and its nature favors continental control; it is a sea of passage and a sea of land powers. For Italy, severed from continental Europe by the Alps, and for Greece, anchored in the Aegean archipelago, the stability of the Mediterranean determines their security and prosperity.
But for other powers, such as Great Britain in the 17 th th centuries and the United States since World War II, the Mediterranean was, and continues to be, important for strategic purposes that go beyond the confines of the immediate basin. This sea is a means of influence or connection, and it matters only insofar that the target to be influenced or connected is relevant. Thus, for Britain, the Mediterranean Sea was a key link to India as well as a means of influencing economic dynamics within continental Europe.
After , for the U. Hence, U. If Europe and to a lesser degree, the Middle East does not matter, then the Mediterranean is a backwater of touristy interest. If it matters, however, the Mediterranean is crucial. Because the Mediterranean is recognized as a lever of influence over Europe, it has always attracted external powers whose interests transcend this sea and focus on Europe.
The rationale for these clashes is rarely the Mediterranean per se but the Mediterranean as a way of extending greater influence over Europe. The prize is not the sea, but the continent. The second characteristic of the Mediterranean is that its unity and stability depend on the ability of one power—or a group of friendly powers—to control its shores and access points.
The Roman Empire managed to achieve this only after the final defeat of Carthage. The Mediterranean Sea receives from the rivers that flow into it only about one-third of the amount of water that it loses by evaporation. In consequence, there is a continuous inflow of surface water from the Atlantic Ocean. After passing through the Strait of Gibraltar, the main body of the incoming surface water flows eastward along the north coast of Africa.
This current is the most constant component of the circulation of the Mediterranean. It is most powerful in summer, when evaporation in the Mediterranean is at a maximum. This inflow of Atlantic water loses its strength as it proceeds eastward, but it is still recognizable as a surface movement in the Sicilian channel and even off the Levant coast. A small amount of water also enters the Mediterranean from the Black Sea as a surface current through the Bosporus, the Sea of Marmara, and the Dardanelles Coll et al.
The Mediterranean region is characterized by winter dominated rainfall and hot dry summers. Even though large spatial climate variability and diversity exist within the Mediterranean basins, many areas can be classified as arid or semiarid. The Mediterranean is an area of transition between a temperate Europe with relatively abundant and consistent water resources, and the arid African and Arabian deserts that are very short of water.
The Mediterranean region is experiencing a large stress on its water resources due to a combination of effects ranging from climate change to anthropogenic pressures due to an increasing water demand for domestic and industrial use, expansion of irrigated areas, and tourism activities.
These resources are unevenly distributed over space. Water resource availability in the Mediterranean has already been affected by environmental change, and is seriously jeopardized in future environmental, economic, and demographic scenarios Garcia-Ruiz et al. Most global hydrological models are based on expected trends in precipitation and temperature.
However, a number of studies have demonstrated the influence of land cover on river discharge and water resources. Climate and land cover change artificial and natural reforestation, deforestation, expansion of farming areas are likely to amplify water stress in the Mediterranean region, caused by a combination of decreased water resource availability lower precipitation and increased evapotranspiration and increased water use pressure resulting from economic growth and urban expansion.
Special attention to mountain areas is required, as they are the most important sites for water resource generation worldwide, and particularly in temperate and semi-arid areas including the Mediterranean basin. However, mountain areas are facing increasing hydrological stress caused by a combination of i increasing temperature and decreasing precipitation, exceeding that in the lowlands; ii land use change, including natural and deliberate reforestation of abandoned farmland, thus increasing evapotranspiration and water consumption; and, iii increasing pressures on surface and groundwater resources, thus reducing river discharge and lowering the depth of the water table in groundwater-dependent areas.
The amount and distribution of rainfall in Mediterranean localities is variable and unpredictable. Maximum precipitation is found in mountainous coastal areas Figure 1. The climate in the region is characterized by hot, dry summers and cool, humid winters. The annual mean sea surface temperature shows a high seasonality and important gradients from west to east and north to south.
Coastal aquifers provide another source of freshwater discharge to the Mediterranean. The submarine groundwater discharge from the coastal aquifers, estimated at 2. Seepage inflows are prevalent on the eastern coast of the Adriatic, dominated by karstic aquifer systems, as well as on the eastern and southern Mediterranean coast with semi-arid and arid conditions, limited precipitation and runoff, and limited surface watercourses and discharge points.
Coastal seepage and submarine discharges are critical to the water balance and seawater quality in the marine sub-basins. They also support wetlands and brackish water habitats, important to biodiversity, and fishery nursery areas. The coastal aquifers are threatened by over-exploitation and consequent seawater intrusion and water and land salinisation, which will add to the deficit in recharge of the Mediterranean.
With a typical tidal range of less than 50 cm, the Mediterranean Sea is microtidal.
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