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The soil


The planet inside and out

The soil you step on; the rocks that shape the mountains; the bottom of rivers, lakes and seas: all this is just a thin "shell" of the immense planet that is Earth.

The land

The earth is roughly spherical in shape and flattened at the poles. Its internal structure is divided into earth's crust, mantle and core.

THE Earth's crust It is the most superficial layer. It is our ground, that is, the part of the planet on which we walk, live, build our homes. On continents, its thickness can be from 30 to 80 km; at the bottom of the oceans ranges between 5 and 10 km.

O cloak below the earth's crust, it is almost 3000 km thick. It is made of material similar to that of the earth's crust, subjected to intense pressure and elevated temperature. The mantle has less rigid parts of pasty consistency formed by molten rocks. The temperature of the mantle increases with depth and should range from about 1000 ° C to 3000 ° C or more at the deep end. The part of the mantle formed by molten rocks is called the magma. When a volcano erupts, magma is expelled and renamed lava.

The outermost part of the mantle together with the earth's crust form the lithosphere (word from Greek: lithos means "stone" and sphaira, "sphere"; "stone sphere").

O core It is located in the central part of the earth, below the mantle, about 3400 km thick. The core can be divided into two parts. The outside, called outer core, is liquid, consisting mainly of molten iron and nickel. The inside, the inner core, mainly contains solid iron. The temperature in the center of the inner core must exceed 5,000 ° C.

Natural sources of hot water

In some parts of the planet, magma is located near the surface, which ends up heating groundwater. This hot water flows in the form of jets: it is the geyser, which can exceed 100ºC in temperature.

In Iceland, hot water from geysers (geyser in Icelandic means 'gushing') is pumped into homes and used for heating.