UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
Do Earth layers ever die?
Question Date: 2015-04-27
Answer 1:

Thanks for asking such a great question! The Earth has many different types of layers. It has thin layers on the surface, which we call strata. These thin layers are made of different types of rocks and are deposited one at a time over very long periods (sometimes millions of years!) Because these layers are not actually living, we don’t say that they ever die.

Sometimes these layers are made by living things, for example small creatures in the ocean make shells and when they die their shells fall to the sea-floor and become part of Earth’s layers. Although some types of rocks are made by living things, the rocks themselves are not living. Even though Earth’s layers are not living and can’t die, they can go through transformations into other types of rocks through a process we call metamorphism. Perhaps you’ve heard of metamorphic rocks? These are types of rocks that changed into another rock type because it was heated to very high temperatures or because it was under a lot of pressure (from overlying layers or in places where mountains are being pushed upwards). Deep under the Earth’s surface, the layers may be heated enough that they completely melt and turn into magma. In this case, the layers no longer exist and the magma that formed from the melted rocks can come out in volcanic eruptions or cool to form a type of rock called an igneous rock.

The Earth also has four major layers: The crust, the mantle, the outer core, and the inner core. Each of these layers acts differently. For example, the crust is on the Earth’s surface and is solid, but the mantle, which is right beneath the crust, flows very slowly through time. It flows so slowly that if you could look at it you wouldn’t notice, but over hundreds or thousands of years it will have moved. Because Earth has a rigid crust, and because the mantle moves slowly through time, we have something called plate tectonics. You may have learned about plate tectonics in class. The surface of the earth is broken into several major tectonic plates and many more small tectonic plates. These plates move through time meaning that in some places plates are moving past each other, in some places they are moving away from each other, and in some places they are colliding with each other. In places where they are colliding with each other, one of the tectonic plates gets “recycled” back into the mantle. The way this happens is one plate goes underneath the other and it sinks down into the hot mantle. The hot mantle then eventually melts the plate and it becomes part of the mantle. This is one way that tectonic plates “die,” but because it was never actually alive we instead think of it as recycling of the material that made up the plates.

I hope this answered your question!


Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use