lithosphere

The lithosphere is the outermost layer of the Earth’s surface. It is rugged, dense, and mostly made out of solid rock.

Generally speaking, Earth is made of a really hot core and layers of rock that get colder the farther you move from the center. The lithosphere is the farthest layer from the core and so is the coldest, made of mostly solid rock.

The lithosphere consists of the crust, the actual surface of Earth that we walk on, and the upper part of the mantle, the rocky majority of the inner Earth between the core and the crust. The lithosphere averages about 75 km in thickness, depending on age.

The lithosphere sits on top of the weaker, denser asthenosphere and slowly floats on top of it. The lithosphere is broken into solid chunks, known as plates, that drift on top of the asthenosphere and move a few inches every year. Sometimes, the plates of the lithosphere collide, break, or rub into each other, which is known as plate tectonics. Plate tectonics is responsible for earthquakes, volcanoes, and a variety of other geologic events.

The first records of the term lithosphere come from around 1885. It combines litho–, which means “stone,” and –sphere, meaning “spherical” or “layer of a sphere.” The lithosphere is the hardest, most solid layer of stone that makes up the spherical Earth.

In addition to the asthenosphere, the lithosphere also regularly comes into contact with other layers of the Earth. For example living creatures from the biosphere interact with rocks to create the nutrient-rich soil. Rain and rivers from the hydrosphere and glaciers from the cryosphere cause erosion and carve the lithosphere into mountains and valleys. And temperature changes depending on interactions between the lithosphere and the atmosphere. High mountain ranges are very cold due to the low air pressure of the atmosphere.

Both the lithosphere and asthenosphere were named by geologist Joseph Barrell in the early 1900s. Prior to Barrell, geologists believed the supposedly solid outer layer of the Earth was created purely by the oceans.

You are very unlikely to hear the term lithosphere from anyone who isn’t a geologist or a geology student.

The puzzle pieces of Earth's lithosphere are always in motion, slamming against each other and grinding past one another. https://t.co/Sp6rFTOk4b

— Discover Magazine (@DiscoverMag) September 11, 2020

Evolution of the Oceanic Lithosphere in the equatorial Atlantic, evidence for small‐scale convection from the PI‐LAB experiment https://t.co/AFkqzwWh9O

— SeismologyNews (@SeismologyNews) September 3, 2020

• geology
• Earth
• crust
• mantle
• asthenosphere
• plates
• plate tectonics

True or False?

The lithosphere is made of soft molten rock that constantly moves, causing earthquakes and volcanoes.