04: Earth's Structure : Icse-ix-geography

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Qstn #1
Name the sources of information about forces operating inside the earth.
Ans : Information about forces operating inside the earth is taken by the study of seismic waves, materials thrown up by volcanoes and the evidence from the theories of the origin of the earth.

Qstn #2
In which part of the earth is NIFE found ? What it is composed of ?
Ans : NIFE is found in the inner core of die earth. NIFE is composed of Nickel (Ni) and Iron (Fe), being heavy metals and having high density, these are found deep inside the earth.

Qstn #3
What are the consequences of the pressure and temperature in the interior of the earth ?
Ans : Due to the extreme temperature of 2200° C, every matter is in liquid and gaseous state in the interior core, the temperature in the mantle ranges from 870° C to 2200° C, so things are in semi - liquid to liquid state, the crust, a layer of 60 km, breadth, is made of solid rocks with a density of 2 - 3, g/Cm³. The density goes on increasing to 3-4g/Cm³ in the mantle and 10-13 g/Cm³ in the core.

Qstn #4
What is the lithosphere ?
Ans : The crust is called Lithosphere made of solid rocks with a thickness of 60 km. below high mountains and 6-12 km below the oceans.

Qstn #6
State two chief characteristics of the earth’s crust.
Ans : The crust is made of solid rocks and divided into oceans and continents.

Qstn #7
Describe the mantle. State its two chief characteristics.
Ans : Mantle lies between 60 - 2900 km. depth. It is divided into two parts namely upper mantle and lower mantle, which are in the form of solid rocks and semi-molten rocks respectively.

Qstn #8
Where is asthenosphere found ? In which form does it exist ?
Ans : At the depth of 100 - 250 km. The mantle is partially molten and known as asthenosphere, with a temperature of 1100°C.

Qstn #9
Write one difference between Moho Discontinuity and Gutenberg Discontinuity.
Ans : Moho Discontinuity is the boundary between crust and mantle while Gutenberg Discontinuity is the boundary between mantle and core.

Qstn #10
Why is the earth’s interior in most part found in a solid state despite great heat and pressure ?
Ans : The solid state of the inner core is due to high density and pressure which have compressed molten rock material and keep this layer firm and solid in some parts due to high pressure inspite of the temperature of 5000°C.

Qstn #11
Name two types of earth movements.
Ans : Two types of movements are due to isostasy and tectonic plates. Isostasy is the process of natural balance between different landforms and the sliding movement of the tectonic plates of the earth’s crust.

Qstn #12
What is Geology ?
Ans : Geology is the science dealing with the origin and types of rocks found in the interior of the earth.