We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Seafloor Spreading?

Michael Anissimov
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Seafloor spreading is a constant geologic phenomenon and a primary driver of continental drift. The process begins when the crust is heated from beneath by upwelling in the mantle, sometimes called a mantle plume. This creates a three-armed rift called a triple junction, usually with each rift at a 120° angle to the rest. The crust along the length of the rift is heated by the underlying mantle, becoming more plastic and less dense. The crust rises, creating a broad dome and widening the rift.

The heated region pushes the crust outwards from the rift ever so slightly, at a rate of 5-10 cm a year, about the same speed fingernails grow, causing the seafloor spreading. Over millions of years, this process drives continental drift, bringing together continents, then dividing them, in a process called the supercontinent cycle. This process runs its course every 250 to 500 million years. The last time there was a supercontinent, Pangaea, was about 200 million years ago. Within the next 200 million years, the world's continents are predicted to agglomerate again, in a new supercontinent called Pangaea Ultima.

In a typical rift system, two of the rifts will continue spreading while one, a "failed rift," stops spreading. If on land, the failed rift will become a rift valley. Rifts that keep spreading are guaranteed to create an ocean, even if they begin on land. The Atlantic Ocean was created when a rift opened between the continents of North America, Africa, and Europe. This rift still exists today, in the form of the Mid-Atlantic Rift, one of the major submarine mountain ranges on Earth.

As seafloor spreading continues, magma rushes up to fill the gap, creating volcanoes and mountains. Rifts are the site of geological activity, including earthquakes. Many of the world's hydrothermal vents are found on or near the rifts that cause seafloor spreading.

When a new rift starts to spread on land, water will rush in, creating a sea. This can be seen in the Red Sea, which separates Eurasia — Saudi Arabia — from Africa — Egypt, Sudan, and Ethiopia. Over millions of years, this rift will continue to spread, creating a new ocean.

Seafloor spreading pushes the margins of oceanic tectonic plates beneath the continental plates, which are lighter. This crust is subducted into the mantle, where it melts and becomes magma. In this fashion, the ocean crust is constantly replenished. The oldest seafloor crust is only about 200 million years old, in contrast to the continental crust, which can be billions of years old.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Anissimov
By Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology, astronomy, chemistry, and futurism to his articles. An avid blogger, Michael is deeply passionate about stem cell research, regenerative medicine, and life extension therapies. His professional experience includes work with the Methuselah Foundation, Singularity Institute for Artificial Intelligence, and Lifeboat Foundation, further showcasing his commitment to scientific advancement.
Discussion Comments
By anon237425 — On Dec 29, 2011

In response to irontoenail's "guess that is why we find ancient seashells in dry mountain ranges." I might agree with your logic. Then if the world was once completely under water, these discoveries of sea shells, fish fossil, and creatures not natural to a given area on the globe might just as easily or more likely fossilized where they landed when the waters subsided. --Drj

By irontoenail — On May 03, 2011

It is so strange to imagine that the ground under our feet is shifting in this way.

It's also weird that the sea floor is so young. I guess that's why sometimes you can find ancient seashells in dry mountain ranges.

Just one more wonder in our world to contemplate.

By anon170485 — On Apr 26, 2011

Oh, what an interesting article. Nice explanation.

Michael Anissimov
Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology...
Learn more
All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.