geosohere
is the solid part of planet
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When the Earth was formed, it was like a ball of hot bubbling
if a liquid bubbles, balls of air or gas rise to its surface
liquid rocks made from different chemical elements and compounds. Some rocks were heavier than others. Over time there was a separation of the rocks:
heavy dense rocks, rich in iron and nickel, started to ‘sink’, moving toward the centre of the Earth;lighter and less dense rocks such as silicates moved towards the Earth’s surface. As these rocks cooled down they became harder.
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This separation took millions of years and ended with the differentiation of three major layers in the geosphere: crust, mantle and core. Most of what we know about the Earth's internal structure comes from the study of seismic waves
wave of energy that is generated by an earthquake
from earthquakes.
crust
The crust is the outermost
at the greatest distance from the centre
layer of the Earth. It is also the thinnest. It is made up of rocky materials in a solid state which form the continents and ocean bottoms. It ranges
to vary between certain limits
in thickness from 6 km to 70 km. The Earth has two types of crust: continental and oceanic.
The continental crust makes up the continents and the shallow areas of the oceans. Its thickness ranges from 25 km to 70 km and is formed by lighter rocks such as granite, limestone, sandstone, slate and gneiss.The oceanic crust makes up the ocean floor. Its thickness ranges from 6 km to 10 km and it is formed by denser rocks than the continental crust, like basalt and gabbro.
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MANTLE
The mantle is the layer that lies directly under the crust and extends to a depth of 2 900 km. It is the thickest layer and contains both solid rocky materials, and fluid and viscous materials. The mantle is, in turn, divided into two layers: the upper mantle and the lower mantle.
The upper part of the mantle is composed mostly of peridotite, a magmatic rock which is denser than the common rocks found in the crust.The lower mantle is even denser and contains a greater amount of iron than the upper mantle.
It is in the mantle where magma, a mixture of minerals, water vapour and other gases at high temperatures, is formed. When volcanoes erupt, magma breaks through the Earth’s crust to the surface.