Tag: geography

The Earth's core is primarily composed of nickel (Ni) and iron (Fe), which is why it is referred to as Nife. Sial and Sima refer to layers of the crust.

Convergent plate boundaries are known as destructive boundaries because tectonic plates collide, leading to the subduction or destruction of lithospheric material.

The habitable portion of the Earth's land area is significantly less than half, as much of the land is covered by deserts, mountains, ice caps, or dense forests that are not suitable for large-scale human habitation.

• The surface of the earth is still irregular in spite of millions of years of gradation, because— material re-elevates the land. Parts of the crust have been uplifted.
  
• Delamination of the lithosphere has two major geologic effects. First, because a large portion of dense material is removed, the remaining portion of the crust and lithosphere undergo rapid uplift to form mountain ranges. 
  
• Second, the flow of hot mantle material encounters the base of the thin lithosphere and often results in melting and a new phase of volcanism.
  
• Delamination may thus account for some volcanic regions that have been attributed to mantle plumes in the past.

• The shape of the Earth is classified as an ellipsoid or an oblate spheroid.
• The Earth is not considered a true sphere because it has a larger circumference and diameter at the equator.
• The poles of the Earth are squished, which creates a slight bulge around the equator.
• The Earth's polar diameter is about 43 kilometers shorter than its equatorial diameter, a difference of about 0.3%.
• This is due to the equatorial bulge caused by the Earth's rotation.

• The latitudinal extent influences the duration of the day and night as one moves from south to north.
  
• The length of day and night depends on whether the place is receiving direct sun rays or slanting rays.
  
• Places on the equator receive the direct rays of the sun all year round and hence have equal days and night.
• Whereas for places north and south equator, the duration varies according to seasons due to the tilt of the earth.

• The distinguishing features of Earth: abundant liquid water (and the temperature required for that), a protective atmosphere, a geological system neither overactive nor dead.
  
• Earth gravitationally interacts with other objects in space, especially the Sun and the moon.
  

• The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly.
  
•  The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets  being primarily composed of rock and metal.
  
•  The four outer planets are giant planets, being substantially more massive than  than the terrestrials.
  
•  For most of history, humanity did not recognize or understand the concept of  the Solar System. 
  

• The total surface area of the earth is 510 million square km approximately or 510,100,500 square km. Hence option A is correct 

• The crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks.