Divergent Plate Boundaries
Lesson notes
Overview
Plates pull apart and magma wells up to create new crust at ridges and rifts. This topic is rated intermediate and is number 2 of 98 in Earth & Space. Builds on the basics with relationships, methods and trade-offs.
What you are seeing
The panel above shows a model of an Earth or space system that you can adjust. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.
In depth
At a divergent boundary two plates move apart, and hot mantle rock rises to fill the gap, melting as the pressure drops and forming new crust. Under the oceans this builds mid-ocean ridges such as the Mid-Atlantic Ridge, where the seafloor spreads at a few centimetres a year. On land it creates rift valleys, like East Africa’s, which may one day split a continent. The boundaries are marked by shallow earthquakes and basaltic volcanism.
Reading the relationship
The expression "seafloor spreading" is a compact summary of the idea. It uses the symbols s, e, a, f, l, o; name what each one stands for before you start. Then use the sliders to see how changing one quantity changes the others.
A guided exploration
1. Run the animation once with the default settings and describe in words what happens. 2. Change one slider at a time and note which quantity responds most. 3. Push each slider to its extreme and decide whether the result still makes sense.
Try this
Predict the outcome first, then test extreme slider values to find where the pattern changes or breaks.
Common pitfalls
Earth and space systems work on very different scales of time and distance. Check which scale a number refers to before comparing it with another.
How it connects
It builds on “Convergent Plate Boundaries”, the topic before it in Earth & Space. Once you are comfortable, continue with “Transform Plate Boundaries”.
Why it matters
Earth and space science helps us understand our planet, its climate and the wider universe.
Where you might use it
- Revising “Divergent Plate Boundaries” before a class, exam or certification
- Forecasting weather and understanding climate records and their uncertainty
- Planning for earthquakes, floods and other natural hazards in cities
- Interpreting satellite images, space missions and the age of rocks and stars
Frequently asked questions
What is Divergent Plate Boundaries?
Plates pull apart and magma wells up to create new crust at ridges and rifts. It is an intermediate topic in Earth & Space.
How do I use the Divergent Plate Boundaries simulation?
The panel at the top shows a model of an Earth or space system that you can adjust. Move the sliders one at a time, then press Space to pause the animation and look closer.
What does the formula mean?
The expression seafloor spreading packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.
Who is this topic for?
Builds on the basics with relationships, methods and trade-offs. If the quiz feels hard, reread the lesson notes and try the previous topic first.
What should I learn before this?
Start with “Convergent Plate Boundaries”, the previous topic in Earth & Space. Each topic in a subject builds on the ones before it.
How do I track my progress?
Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.
Quick quiz
More in Earth & Space
See all →Transform Plate Boundaries
Plates grind sideways past each other; stress released suddenly causes earthquakes.
Seafloor Spreading
New oceanic crust forms at mid-ocean ridges and moves away, recording Earth’s magnetic reversals.
The Rock Cycle
Rocks continually change between igneous, sedimentary and metamorphic forms.