Geology- It is the science that deals with nature and earth history. Example- the study of rocks and stones; how the earth was formed, etc.
Physiography– It is the study of physical patterns and processes of the earth.
Endogenic Forces– Horizontal and vertical movements caused by the forces coming from the origin of the earth.
Exogenic Forces– External processes that occur above the earth’s surface.
Theory of tectonic plates– The crust of the earth has been formed out of seven major and some minor plates. The movement of the plates results in the building up of stresses leading to folding, faulting, and volcanic activity. Given by scientist ALFRED WEGENER IN 1912.
Structure of the Earth:
LAYERS OF EARTH
Just like an onion, the earth is made up of several concentric layers with one inside another.
The uppermost layer over the earth’s surface.
It is the thinnest of all the layers.
It is about 35 km on the continental masses and only 5 km on the ocean floors.
Oxygen is the largest constituent of crust.
It is present in the form of oxides of various elements.
Silicon is the second-largest substance.
CRUST IS OF 2 TYPES
CONTINENTAL CRUST– It is the thick part of the earth’s crust which forms the large landmasses. The main mineral constituents are –Silica and Aluminium also called as Sial. Thickness is around 30 km.
OCEANIC CRUST– It is the thin part that underlies the ocean basins. The main mineral constituents are –Silica and Magnesium also called as Sima. Thickness is 5 km. Basalt is the type of rock found in the oceanic crust having a density of 3g/cm3
It is the largest layer.
It has a higher density than that of crust.
The main mineral constituents elements are- oxygen(44.8%), silicon(21.5%), and magnesium(22.8%).
It contains a weaker zone called the Aesthenosphere(the upper part of the earth’s mantle).
Rock is hard in upper part and soft in the lower part.
Located under sima.
Temperature varies between 1600°F at upper part to 4000°f near the bottom.
It is the innermost layer of the earth.
Radius is 3500 km.
It is in solid state due to high temperature of central core and pressure.
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