The Amazing Adventure of Sea‑floor Spreading

What Is Sea‑floor Spreading?

Deep under the ocean, the Earth’s crust is not solid rock that never moves.
It is made of huge plates that float on a hot, liquid layer called the Mantle.
When the mantle pushes the plates apart, new rock is made and the ocean floor Spreads.

How It Works

1. Magma Rises – Hot, melted rock (magma) climbs up through cracks in the crust.
2. New Rock Forms – When the magma touches the cold ocean water, it solidifies into new rock.
3. The Plates Move – The new rock pushes the old crust away on both sides of the crack.

The biggest crack is the Mid‑ocean Ridge. It is a long underwater mountain chain that circles the globe. The longest part is the Mid‑atlantic Ridge, which runs right through the middle of the Atlantic Ocean.

Why It Matters

• Creates New Ocean Floor – Every few million years, the sea floor gets fresh rock.
• Moves Continents – As the ocean floor spreads, the continents on top of the plates drift slowly.
• Makes Earthquakes And Volcanoes – The moving plates sometimes get stuck, and when they finally slip, they cause earthquakes. The magma that rises can also form underwater volcanoes.

Quick Quiz

1. What Is The Hot Liquid Layer Beneath The Earth’s Crust Called?
   a) Crust b) Mantle c) Core d) Atmosphere

2. Which Underwater Mountain Chain Is The Longest Mid‑ocean Ridge?
   a) East Pacific Rise b) Mid‑Atlantic Ridge c) Southwest Indian Ridge d) Mariana Trench

3. How Fast Does The Atlantic Ocean Spread Each Year?
   a) 2–5 meters b) 2–5 centimeters c) 20–50 centimeters d) 0.2–0.5 centimeters

Great job! You now know how the ocean floor is always on the move. 🌍✨.