The endosphere

   1. The endosphere
   It is the interior of the Earth placed below the lithosphere (120 km thick).
   According to geologists and geophysicists, the endospehre consists of concentric zones of increasing density toward the center. These zone are: the atmosphere (a), hydrosphere (b), the lithosphere (c) and
   - The mantle or outer core (d) with 1,200 km thick and a density from 2.7 to 5 comprising feldspars.
   - The middle core (e), with 1,700 km thick and a density from 5 to 9, formed by ferromagnesian silicates.
   - The inner core (f) or NiFe, formed by nickel and iron of about 3400 km and an increasing density from 9 to 11, completely solid and greater stiffness than the steel.
   In the middle core, rocks have a plasticity condition due to the high pressure and the high temperatures; pressure tends to solidify them and temperature tends to melt them. When the pressure decreases through a crevice in the lithosphere, the rocks melt and the pressure exerted by the gases causes the expulsion of those rocks as magma.

   2. Choose one of these words: mantle, the middle core or the inner core:

There are feldspars

It consists of nickel and iron

There are ferromagnesian silicates

Core of 3.400 km thick

Core of 1,200 km thick

Core of 1700 km thick

    3. Volcano

   The activity of the Earth manifests through volcanoes, hot springs and earthquakes.
   If an opening or crack in the earth's crust occurs, the molten material inside the Earth rise to the surface, resulting in a volcano.
   Volcano is the rupture which allows the materials placed in the Earth's interior escape. Conical mountains are usually formed. The parts of the volcano are:
   - The volcanic cone: it is a hill formed by lava.
   - The volcanic pipe: it is the conduit where materials are ejected.
   - The volcanic crater: it is the mouth where the pipe ends.
   There are inactive and active volcanoes. Vesuvius volcano (Italy) was apparently extinct but it activated and destroyed the city of Pompeii.
   Volcanoes are usually located near the seas. The most important are those that form the “Pacific Ring of Fire “.

   4. Choose one of the parts of the volcano and answer: cone, pipe or crater:

Conduit where materials are ejected

Mouth of the pipe

Hill formed by lava

    5. The hot springs

   They are springs of heated water that usually have healing benefits.
   When intermittent discharges of water are ejected, it is called geysers. Some of them reach 150 meters high in Yellowstone National Park in the United States

    6. Earthquakes

   They are jerky movements of earth's crust. In general they are very violent and last about one second. They happen when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault.

   The region where the movement originates is called the hypocenter. The depth of focus does not reach 30 km. From the hypocenter, concentric waves that reach the earth's crust spread. (See the side picture).

   The region of the Earth's surface closest to the hypocenter is called the epicenter. When the focus is on the sea is called tsunami. The instruments that measure earthquakes are called seismographs.

   7. Answer if these sentences are true or false:

The hot springs are healing

Earthquakes last several hours

The geysers have cold water

Earthquakes occur when two blocks of the earth suddenly slip past one another

The hypocenter is on the surface

Focus is more than 30 km

The focus of the tsunami is on the sea

The epicenter is in the earth's surface

The thermometer measures tsunamis

The earthquake is measured by the seismograph

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®Arturo Ramo García.-Record of intellectual property of Teruel (Spain) No 141, of 29-IX-1999
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