The lithosphere is the solid, outer layer of the Earth, and it is around 100 kilometers thick. It consists of the brittle upper portion of the crust and mantle. It is divided into huge sections called tectonic plates, on which the continents sit.
According to National Geographic, the movement of the lithospheric plates, called plate tectonics, is responsible for many geologic events on Earth. Earthquakes and volcanoes are created when plates move beneath each other or when two plates rub against one another. Scientists believe that the continents originated from a single landmass known as Pangaea. The lithosphere broke apart, resulting in the separation of Pangaea into different landmasses.
According to Encyclopedia World of Earth Science, the lithosphere extends from the Earth’s surface to a depth of approximately 70 to 100 kilometers. This relatively cool, rigid section “floats” on top of a warmer, partially melted and non-rigid material. The temperature reaches 1,000 degrees Celsius below the lithosphere, allowing rock material to flow when pressurized. Based on seismic evidence, there is also around 10 percent molten material at this depth.
The zone beneath the lithosphere is the asthenosphere. Windows to the Universe states that the asthenosphere is ductile, and it can be deformed and pushed. When it flows, it carries the lithosphere and continents above it.