Importance of water

Reservoirs of water on Earth

It seems that once formed the Earth, there are 4.5 billion years, contained in his burning atmosphere, all the water in vapor form.
It is this vapor will condense when, much later form the oceans, there are 3.8 billion years.
All this water is now, the temperature regulator on the planet Earth. Thus, through its cycle of evaporation and precipitation, and circulation of water in the oceans, the energy received by Earth is temperature controlled, over all latitudes of the globe.
Water is the only element on Earth, under the conditions of temperature and pressure, is found in the state, solid, liquid and gas.

The ocean surface is 3.6 x10⁸ km2, a simple calculation, if all the ice stored in ice caps and glaciers based, rising sea level would be 120 meters.
During the last two million years, Earth has fluctuated very important sea level.
It fluctuated between 7 meters and -130 meters at the option phases glaciations and iron and this without taking into account the rate of evaporation modified, changes in the circulation of ocean waters and especially the expansion of ocean water related to global warming.

Area of land

The average sea level enables us to define the references altitudes and depths of the earth's crust. While nothing seems more fixed than the coastal zone that separates the sea from the mainland, rocks and fossils show the opposite, showing significant displacement of the coastline in geological time. The analysis of sedimentary layers, made by scientists reveal these climbs and descents sea level over geological time. Sea-level changes at different scales punctuate the history of the Earth and its climate, low sea levels associated with relatively cold climates while in the high sea levels, climates are warmer. The area of land has varied considerably and their limitations are traced through the mapping of former marine and continental deposits. Western Europe has the aspect that we know today than a few tens of thousands of years. On maps this against the current outline the contours of coastlines can represent the movement of tectonic plates, with rotation and shift to the east of the Iberian peninsula, Corsica and Sardinia, compared to France.

NB: In geology, a marine transgression is the invasion of the continents by sea due to subsidence of the land surface or to a general rise in sea level.

Image: There are about 155 million years, only emerging in the South-West Europe and the massive armoricains Ardennes region of the Ebro and west of the Iberian Peninsula. The marine transgression covers almost all of France.

Image: There are 65 million years, discovered a regression most of France and the Iberian Peninsula.
credit 1996: Jacques Rey, a professor at the University Paul Sabatier in Toulouse and René Cubaynes, professor in the school Lapeyrouse, in Albi.