Tag: components of earth

The oceanic crust consists of a volcanic lava rock called basalt. Oceanic crust is the thin crust underlying the oceans. Basalt is dark coloured igneous rock mainly composed of pyroxene mineral. It most commonly forms as an extrusive rock, such as a lava.

Basalt density present is equal to 3.0 g cm'3

Earth mainly consists of four layers namely crust, mantle, outer core and inner core.

Lithosphere is the rigid outer layer of the earth which includes crust and uppermost mantle.

Crust: This is about 8 km thick inside and is highly explored. The continental crust is composed mostly of granite. The oceanic crust consists of a volcanic lava rock called basalt.

Mantle: It is composed mostly of silicate rocks rich in magnesium and iron.

The topmost layer of the earth is solid, the thinnest and the lightest and is known as lithosphere. The lithosphere has two layer- the outer part and the inner part. The outer part which is immediately below the newer sedimentary formation, i.e, crust. The outer layer of lithosphere mainly found under the continent and inner layer it mostly found partly under oceans. The inner layer again has three layers, i.e, SIAL which is made of silica and aluminum. The average thickness is 8 to 100 km. The layer next to it is SIMA makeup of silica and magnesium and an average thickness of this layer is 100 to 2900 km. The innermost layer is NIFE madeup of nickel and ferrous and the density is 5.1 to 13.

• The hard resistant materials forming the earth's crust are called the rocks. Hence option A is correct
• In different types of rocks, different metals and minerals are found.
• Lava is the molten material that gets ejected out of a volcano.

• The earth's crust is the outermost layer of the earth which has cooled down while the inner layers are still burning. When things cool after burning they get wrinkled up hence the earth's crust is largely wrinkled.
• It is plain, plateau and mountainous at different places and rocky as well. The most appropriate answer is option C ie wrinkled.

• The core of the earth is made up of heavy minerals like iron and nickel hence statement in option A is incorrect which makes it the right answer.
• Rest statements are true 
• The outer core is made up of molten rocks, its estimated temperature is 3300 degrees C and the inner core acts like a solid mass.
• Note- inner core is solid and the outer core is liquid.

Fold mountains are formed due to the folding of crustal rocks by compressive forces generated by the movements inside the earth. Thus fold mountains can be said to be caused by the influence of internal forces. These are the highest and most extensive mountains of the world and are found in all the continents.

Earth is slightly bulged out towards the equator due to the spin. If the rotation stops, the shape might not change immediately, but water and atmosphere would go to the poles making it thicker there. Mid way through the equator and poles, the region will have moderate pressure. Gravity makes it spherical. Earth spin then extends it out at the equator and flattens it at the poles.

The outer or upper layer of the earth's crust is mostly found under the continent. Silica and aluminum are abundantly found in this layer therefore it is popularly known as SIAL. The average density of the layer is 2.75 to 2.90 and the average thickness is 8 to 100 km.

Mental is the middle layer of the earth lies between crust and core. The average thickness of this layer is 100 to 2900 km. Silica and magnesium elements predominate in this layer so it is known as SIMA.  Density of the layer varies between 3.1 to 5.00. It has two layers: upper mantle and lower mantle.