Which is the outermost layer of the earth composed of crust and upper mantle?

The correct answer is the lithosphere.

Key Points

• T he lithosphere is the solid, outer part of the Earth.
• It is an irregular surface with various landforms such as mountains, plateaus, deserts, plains, valleys, etc.
• It includes the brittle upper portion of the mantle and the crust.
• It is bounded by the atmosphere above and the asthenosphere below.

Additional Information 

• The mesosphere is the 3rd layer of Earth's atmosphere.
  • It extends from about 50 to 85 km above our planet.
  • The mesosphere burns up most meteors and asteroids before they are able to reach the earth's surface.
• The stratosphere is the 2nd layer of Earth's atmosphere.
  • It extends around 6 to 20 km above the Earth's surface.
  • This is where you'll find the very important ozone layer which helps protect us from ultraviolet radiation (UV) from the sun.
• The asthenosphere is the mechanically weak and ductile region of the upper mantle of Earth.
  • It lies below the lithosphere, between approximately 80 and 200 km below the surface, and extends as deep as 700 km.
  • It enables the tectonic plates to move because the material under them can flow.