Environment: Earth and Lithosphere
Planet Earth contains three compositional layers- CORE, MENTLE & CRUST.
Core: At the centre is the densest of the three layers, the core. The core is a spherical mass, composed largely on metallic iron, with lesser amount of nickel and other elements.
Mantle: The thick shell of dense, rocky matter that surrounds the core is mantle. The mantle is less dense than the core but denser than the outer most layer, the crust.
Crust: Above the mantle lies the thinnest and outermost layer, the crust, which consists of rocky matter that is less dense than the rocks of the mantle below. The thickness of crust is not uniform rather it differs from place to place by different factors.
The crust beneath the ocean is called oceanic crust which has an average thickness of 8 km.
The continental crust has an average thickness of 45 km and ranges from 30 km to 70 km.
LAYERS OF DIFFERING PHYSICAL PROPERTIES
The inner and outer core:
Within core a inner region exists where the pressure are so great that the iron is solid despite its high temperature. The solid centre of the earth is the inner core.
Surrounding the inner core is a zone where temperature and pressures are so balanced that the iron is molten and exists as liquid. This is the outer core.
The inner core is solid and outer core is liquid. It is believed that the compositions of both are same. The difference is with their physical state.
The strength of a solid is controlled by both temperature and pressure. When a solid is heated, it losses strength. When it is compressed, it gains strength. Differences in temperature and pressure divide the mantle and crust into three strength regions.
The Mesosphere:
In the lower part of the mantle the rock is so highly compressed that it has considerable strength even though the temperature is very high. Thus a solid region of high temperature but also relatively high strength exists within the mantle from the core mantle boundary (at 2883 km depth) to a depth
Core: At the centre is the densest of the three layers, the core. The core is a spherical mass, composed largely on metallic iron, with lesser amount of nickel and other elements.
Mantle: The thick shell of dense, rocky matter that surrounds the core is mantle. The mantle is less dense than the core but denser than the outer most layer, the crust.
Crust: Above the mantle lies the thinnest and outermost layer, the crust, which consists of rocky matter that is less dense than the rocks of the mantle below. The thickness of crust is not uniform rather it differs from place to place by different factors.
The crust beneath the ocean is called oceanic crust which has an average thickness of 8 km.
The continental crust has an average thickness of 45 km and ranges from 30 km to 70 km.
LAYERS OF DIFFERING PHYSICAL PROPERTIES
The inner and outer core:
Within core a inner region exists where the pressure are so great that the iron is solid despite its high temperature. The solid centre of the earth is the inner core.
Surrounding the inner core is a zone where temperature and pressures are so balanced that the iron is molten and exists as liquid. This is the outer core.
The inner core is solid and outer core is liquid. It is believed that the compositions of both are same. The difference is with their physical state.
The strength of a solid is controlled by both temperature and pressure. When a solid is heated, it losses strength. When it is compressed, it gains strength. Differences in temperature and pressure divide the mantle and crust into three strength regions.
The Mesosphere:
In the lower part of the mantle the rock is so highly compressed that it has considerable strength even though the temperature is very high. Thus a solid region of high temperature but also relatively high strength exists within the mantle from the core mantle boundary (at 2883 km depth) to a depth