How thick is the lithosphere?

The correct answer is 10 to 200 kilometres.

Key Points

•  The crust and the uppermost part of the mantle are called the lithosphere. Its thickness ranges from 10-200 km. 
• The lithosphere is the solid, outer part of the Earth.
• The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth’s structure.
• It is bounded by the atmosphere above and the asthenosphere (another part of the upper mantle) below.
• The portion of the interior beyond the crust is called the mantle.
• The mantle extends from Mohorovicic discontinuity to a depth of 2,900 km.
• The upper portion of the mantle is called Asthenosphere.
• It is considered to be extending up to 400 km and it is the main source of magma that finds its way to the surface during volcanic eruptions.

Additional Information There are two types of lithosphere: 

• Oceanic lithosphere, which is associated with oceanic crust and exists in the ocean basins (mean density of about 2.9 grams per cubic centimeter)
• Continental lithosph ere, which is associated with continental crust (mean density of about 2.7 grams per cubic centimeter)
• The thickness of the lithosphere is considered to be the depth of the isotherm associated with the transition between brittle and viscous behavior.
• The temperature at which olivine begins to deform viscously (~1000 °C) is often used to set this isotherm because olivine is generally the weakest mineral in the upper mantle.
• Oceanic lithosphere is typically about 50–140 km thick (but beneath the mid-ocean ridges is no thicker than the crust), while continental lithosphere has a range in thickness from about 40 km to perhaps 280 km; the upper ~30 to ~50 km of the typical continental lithosphere is the crust.