Why Continents Are High

Lots of geological forces need to come together for continents to form, but they all require one ingredient: water.

LEARN MORE
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To learn more about this topic, start your googling with these keywords:
- Tectonic plate: Earth’s rigid outer layer is broken up into a bunch of pieces, called tectonic plates. Usually people think of tectonic plates as the Earth’s crust, but the plates are actually made of the crust PLUS the very top of the mantle, which is cool enough to be rigid and hard and stuck to the crust. The crust and the top of the mantle together are called the “lithosphere.” Underneath that is a part of the mantle called the “asthenosphere,” which is the part that oozes and flows.
- Subduction Zone: The area where two tectonic plates collide and the denser of the two is forced under and dives down into Earth’s mantle.
- Mariana Trench: The subduction zone where the Pacific Plate slides under the Philippine Plate. The edge of the Philippine plate is kind of pulled down in the process, creating a deep crevice in Earth’s surface, known as a deep ocean trench. The Mariana Trench is the deepest ocean trench in the world.
- Granite: A type of igneous rock formed when magma cools slowly underground (creating relatively large crystals). Granite is different from other igneous rocks like basalt because it has a higher percentage of low-density minerals like quartz and feldspar.
- Oceanic-Continental Convergent Plate Boundary: The boundary between a tectonic plate made of oceanic lithosphere and a tectonic plate made of continental lithosphere. At these “convergent” plate boundaries, the two plates are colliding, and the oceanic plate is forced to subduct, or sink, under the continental plate.
- Ring of Fire: A long stretch around the Pacific Ocean where plates are colliding. The majority of volcanoes and earthquakes in the world take place along the Ring of Fire.
- Silicate minerals: These are the low-density minerals like quartz and feldspar. They contain SiO2. Because silicate minerals are thick/viscous when melted, magma with lots of silica in it forms very explosive volcanoes, like Mt. St. Helens and Mt. Tambora.

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CREDITS
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Emily Elert | Script Writer and Narrator
Kate Yoshida | Director
Sarah Berman | Illustration, Video Editing and Animation
Nathaniel Schroeder | Music

MinuteEarth is produced by Neptune Studios LLC

OUR STAFF
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Lizah van der Aart • Sarah Berman • Cameron Duke
Arcadi Garcia i Rius • David Goldenberg • Melissa Hayes
Alex Reich • Henry Reich • Peter Reich
Ever Salazar • Leonardo Souza • Kate Yoshida

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REFERENCES
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Collins, W.J. (2022) Personal communication.

[squeebers]

As soon as you mentioned that most of the continental crust is made of granite, I was WAITING for that pun at the end haha great stuff

[davidg]

It's funny to think of granite as a light rock, because among the "common" rock types (the ones we use for construction, artwork, gravestones, etc.) it is actually one of the hardest and densest.
It just serves as another reminder that we only live on the very thin surface of an entire rocky planet, most of which we don't (or barely) have physical access to.

[StarLupus]

This is actually a surprisingly interesting topic! Thanks for making this, MinuteEarth!

[coolpoolbymatthew]

*MinuteEarth be over here answering questions we never even had!*

[kainwi]

I never thought of granite being low density. Have you ever tried to lift up a large slab of it.

[teslaromans]

I had never heard of this before, I always thought the continents were there since Earth’s cool down and that was it. What a fascinating video !

[raideveloper]

For YEARS I had this question on mind, after seeing those maps with the continental shelf vs deep ocean and how the depth changed suddenly, but never had a talk with a geologist to ask it, thanks!

[hammerhand]

completely unrelated note: Granite is super hard and difficult to mine through and it is all across the Sierra Nevadas which is a very big mountain range in California so when they were building the Trans Continental Railroad across the Sierra Nevadas they had to dig through the mountains rather than go over them but that meant digging through granite. The Solution that was used was using Nitroglycerin which is very very explosive at each of the tunnels ends but that was still to slow so sometimes in extra large tunnels they would dig down and then out so there would be 4 parts of the tunnel being dug or exploded out at once

[sahanavica.]

Thank you for this video! I was teaching tectonic plates for the first time recently, and was confused as to whether new continental crust could ever form at all, since I assume divergent plates can only form oceanic crust on the sea floor.

[PauxloE]

0:32 The image is a bit misleading: Actually the continental crust also goes downward (deeper than the sea crust), and "swims" on the underlying mantle like a ship in water.

[dannyso]

i've been following this channel since the beginning, 2:30 was the best pun by far

[GabbyGabbyPatty]

OMG I love that Emily Elert is back narrating again!!!

[Shxealyn]

I found this channel 7 days ago and I love your videos

[digitalatlasproject]

Another great video from MinuteEarth! Thanks for making our jobs as geography teachers a whole lot easier.

[lovelyYN]

So glad to heat Emily’s voice again! It has been awhile. Hope she will narrate more video! 😊

[Corruptedhope]

It’s been soooo long Emily narrated a video. I almost thought she was gone

[whiteacedia]

Your videos are always so fun to watch! Thank you!

[rossjennings]

This is really cool. It directly answers two questions that I learned to ask when comparing Earth with other planets and moons in our solar system (how Earth's elevation profile got to be so bimodal, and why only the ocean floor is made out of basalt, when on the other rocky planets and the Moon almost everything is), and it also indirectly answers a question that I've had for a long time about Earth's early history (why we think that, early in its history, Earth had less continental crust). I wasn't sure I would ever get a good answer to any of those questions.

[DracarmenWinterspring]

Wait, does that mean Earth's surface was mostly smooth until after it got its water (which IIRC is assumed to have come from comets and such, not being there from the start)?
And what about the topography of a place like Mars - does it mean Mars used to have a lot more water than what we've detected, or could it all have been formed by other processes (volcanoes, meteor impacts)?

[LavenderLushLuxury]

One of the best YouTube Channels...!!! NOT just a, Good Great Science Channel, I always look forward to your, Earth and Space Science Videos 🪨🌊🌍