Layers of the Earth Quiz at a Glance
The Earth has four main layers: the crust, the mantle, the liquid outer core and the solid inner core. This diagram shows them in a cross-section, with a close-up of the crust, the lithosphere and the asthenosphere. Tap the part named, or the one described, and print the worksheet for class.
- Main layers
- Crust, mantle, outer core, inner core
- Parts to find
- 10
- Distance to the centre
- About 6,371 km
- Hottest
- Inner core, about 5,200 ยฐC
- Worksheet
- Blank and answer key, one A4 page
- Cost
- Free, no sign-up
How to Play the quiz
- Before a round, the diagram shows every name: study it, or tap any dot to see what it is.
- Pick a round: the four main layers, every part, or "What does it do?", where a description is given instead of a name.
- Tap the dot for the part named. Right turns green; wrong shows you where it was.
- Print the worksheet (blank, with numbered parts) and its answer key for a lesson or homework.
The four main layers
The crust is the thin outer skin, 5 to 70 km thick: thin, heavy basalt under the oceans (oceanic crust) and thick, lighter rock like granite under the continents (continental crust). The mantle below it reaches about 2,900 km down and makes up about 84% of the Earth's volume: the upper mantle to about 660 km, then the lower mantle. The outer core, from 2,900 to about 5,150 km, is liquid iron and nickel; its slow flow makes the Earth's magnetic field. The inner core, a solid ball of iron and nickel with a radius of about 1,220 km, is about 5,200 ยฐC, close to the temperature of the surface of the Sun.
Lithosphere, asthenosphere and the Moho
The lithosphere is the crust and the rigid top of the mantle together, about 100 km thick. It is broken into the tectonic plates. Below it, the asthenosphere is hot, soft rock that flows very slowly, and the plates slide over it. The Moho (the Mohoroviฤiฤ discontinuity) is the boundary between the crust and the mantle, found in 1909 by the Croatian scientist Andrija Mohoroviฤiฤ from the way earthquake waves speed up there.
Frequently Asked Questions
What are the four layers of the Earth?
The crust, the mantle, the outer core and the inner core, from the outside in.
Which layer of the Earth is liquid?
The outer core, made of molten iron and nickel. The magma that feeds volcanoes comes from the mantle and crust, which are mostly solid rock.
How do we know what is inside the Earth?
Mostly from earthquake waves. Some kinds of wave cannot pass through liquid, and they disappear on the far side of the Earth from an earthquake: that showed the outer core is liquid.
Which is the thickest layer?
The mantle, about 2,900 km thick, with most of the Earth's volume.
Made by Kashif Sulehria in Lahore, Pakistan. Updated November 2, 2026.