lithosphere

/ˈlɪθəˌsfɪr/
noun
  1. The solid outer layer of the Earth, including the crust and the upper part of the mantle.
    • Earthquakes occur when stress builds up in the lithosphere and suddenly releases.
    • Scientists study the lithosphere to understand how mountains and volcanoes form.
    • The lithosphere is broken into tectonic plates that move slowly over time.