Divergent Boundary: Definition & Examples

Lesson Transcript
Instructor
David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Expert Contributor
Christianlly Cena

Christianlly has taught college Physics, Natural science, Earth science, and facilitated laboratory courses. He has a master's degree in Physics and is currently pursuing his doctorate degree.

A divergent boundary is where two tectonic plates are moving away from each other, leaving a gap between them that can be filled with magma. Explore the definition and features of divergent boundaries, as well as examples in this lesson. Updated: 09/17/2021

What is a Divergent Boundary?

You've just boiled an egg and are removing the shell. Suddenly; it slips from your hand and hits the floor with a crack. You pick it up to find the whole surface littered with lines and breaks. While nobody has ever dropped the Earth (as far as we know!), the cracked surface of the egg is just like the Earth's crust. While it might seem solid enough, it is actually broken into sections called tectonic plates. These plates float on a sea of hot magma. This magma is solid but becomes a liquid when it reaches the surface through volcanoes.

A divergent boundary, or constructive boundary, is where two sections of the eggshell - two tectonic plates - are moving away from each other. When this happens, they leave a gap in-between, and this gap can be filled by the magma from below. This creates a series of volcanoes all the way along the boundary.

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Hertz: Definition & Concept

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:01 What Is a Divergent Boundary?
  • 0:54 Features of Divergent…
  • 2:34 Examples of Divergent…
  • 3:23 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Timeline
Autoplay
Autoplay
Speed Speed

Features of Divergent Boundaries

Exactly what happens when two plates diverge depends on the two types of plates involved: oceanic plates and continental plates. Oceanic plates are, unsurprisingly, plates below sea level and under the oceans. But the 'oceans' part isn't actually what makes it an oceanic plate because there are some exceptions to this rule. Instead, it's more about the plate's composition. Oceanic plates are composed of mafic or basaltic rock. Continental plates are indeed above sea level, but again, what makes a plate officially continental is the presence of felsic or granitic rock.

Most divergent boundaries in the world today are between two oceanic plates. When these plates separate, the magma rushes up to fill the gap and creates underwater volcanoes. This is the creation of brand new crust! This crust can remain deep under the oceans, creating underwater ridges, or it can rise to the surface over time to form islands.

When two continental plates separate, it is theoretically possible for a similar thing to happen; volcanoes could form to create new crust. However, continental plates are far thicker than oceanic ones. Because of this, what usually happens instead is that a continent will gradually break apart, as water from the sea rushes in to fill the gap. By the time magma has a gap to fill, that gap is already deep underwater in a brand new ocean. This starts out as an enormous rift valley across the land, until that valley fills with water.

When one continental and one oceanic plate diverge, there can be features of both. It is more a matter of whether the boundary itself lies over an ocean or land than whether the plates are continental or oceanic.

Examples of Divergent Boundaries

The mid-Atlantic ridge is an example of a divergent boundary, where the Eurasian Plate that covers all of Europe separates from the North American Plate. This underwater mountain range is constantly growing as new crust is formed. Further up that same boundary, it passes through Iceland. There it forms characteristics of a continental divergence, and a rift is forming on the island. Eventually, Iceland will break into two separate islands, with sea in between.

To unlock this lesson you must be a Study.com Member.
Create your account

Additional Activities

Divergent Boundary: True or False Activity

This activity will help assess your knowledge of the definition and examples of divergent plate boundaries.

Directions

Determine whether the following statements are true or false. To do this, print or copy this page on a blank paper and underline or circle the answer.

True | False 1. The constantly-evolving Himalayas is an example of a divergent boundary.

True | False 2. At the constructive boundary, the plates move away from one another.

True | False 3. Continental plates are thinner and more buoyant than oceanic plates.

True | False 4. It is possible for two continental plates to separate and form volcanoes in between.

True | False 5. One of the most common rocks that makes up the seafloor is called basalt.

True | False 6. The location and shape of continents were all caused by the movement of the tectonic plates.

True | False 7. The Mid-Atlantic volcanoes are the constructive boundary between the North American and Eurasian Plates in the North Atlantic.

True | False 8. It is impossible for a continental and an oceanic plate to diverge and drift.

True | False 9. The complete separation of the Somali and Nubian plates is thought to create a new ocean in between.

True | False 10. There are two types of divergent plate boundaries, namely continental-continental and oceanic-oceanic.


Answer Key

  1. False, because the correct statement is: The constantly-evolving Himalayas is not an example of a divergent boundary.
  2. True
  3. False, because the correct statement is: Continental plates are thicker and more buoyant than oceanic plates.
  4. True
  5. True
  6. True
  7. False, because the correct statement is: The Mid-Atlantic Ridge is the constructive boundary between the North American and Eurasian Plates in the North Atlantic.
  8. False, because the correct statement is: It is possible for a continental and an oceanic plate to diverge and drift.
  9. True
  10. False, because the correct statement is: There are three types of divergent plate boundaries, namely continental-continental, oceanic-continental, and oceanic-oceanic.

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back

Resources created by teachers for teachers

Over 30,000 video lessons & teaching resources‐all in one place.
Video lessons
Quizzes & Worksheets
Classroom Integration
Lesson Plans

I would definitely recommend Study.com to my colleagues. It’s like a teacher waved a magic wand and did the work for me. I feel like it’s a lifeline.

Jennifer B.
Teacher
Jennifer B.
Create an account to start this course today
Used by over 30 million students worldwide
Create an account