What happens to the lava's surface in water?

It chills into a crust instantly

Why do geologists visit Cyprus' Troodos Mountains?

Ancient sea floor with pillow lava is exposed

Pillow Lava Quiz: How Lava Erupts on the Deep Sea Floor

This pillow lava quiz dives down to watch lava meet seawater. Play 10 interactive questions on an outer crust that chills instantly, lava budding out into new pillows, glassy rinds, mid-ocean ridges where much of it forms, divers filming lava entering the sea in Hawaii, pillows under glaciers, ancient sea floor raised onto land in places like Cyprus and what pillows tell geologists.

Start Pillow Lava Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Where
Where does pillow lava form?
Crust
What happens to the lava's surface in water?
Bud
How do new pillows form?
Shape
What shape are the blobs?
Rind
What forms on the outside of pillows?
Ridge
Where does much pillow lava form today?
Hawaii
Where have divers filmed pillow lava forming?
Ice
What can lava erupting under a glacier form?
Cyprus
Why do geologists visit Cyprus' Troodos Mountains?
Clue
What does pillow lava on land tell geologists?

Explanations: answer key for all 10 questions

Q1: Where does pillow lava form?
Answer: Underwater or under ice
Water chills the lava fast.
Q2: What happens to the lava's surface in water?
Answer: It chills into a crust instantly
The inside stays molten.
Q3: How do new pillows form?
Answer: Lava breaks through the crust and buds out
Each pillow grows from the last.
Q4: What shape are the blobs?
Answer: Rounded, like pillows
They stack on each other.
Q5: What forms on the outside of pillows?
Answer: A glassy rind
Fast cooling prevents crystals.
Q6: Where does much pillow lava form today?
Answer: Along mid-ocean ridges
Plates spread apart there.
Q7: Where have divers filmed pillow lava forming?
Answer: Off Hawaii
Lava flows into the sea.
Q8: What can lava erupting under a glacier form?
Answer: Pillow lava too
Iceland has examples.
Q9: Why do geologists visit Cyprus' Troodos Mountains?
Answer: Ancient sea floor with pillow lava is exposed
It is an ophiolite.
Q10: What does pillow lava on land tell geologists?
Answer: The rock once erupted underwater
It records ancient seas.

When Lava Meets the Sea

Pillow lava forms when lava erupts underwater or beneath ice. Water chills the lava's surface instantly into a crust, while the inside stays molten. Pressure builds, lava breaks through the crust and buds out into a new rounded blob, and pillows stack on top of each other like a pile of cushions.

Fast cooling leaves a glassy rind on the outside of each pillow, since crystals have no time to grow. Much pillow lava forms today along mid-ocean ridges, where plates spread apart and new sea floor is made. Divers have filmed pillow lava forming where lava flows into the sea off Hawaii, and eruptions under glaciers in Iceland create it too.

When pillow lava is found on land, it tells geologists the rock once erupted underwater. In Cyprus, the Troodos Mountains expose ancient sea floor, called an ophiolite, full of pillow lavas, helping scientists understand plate tectonics.

What This Quiz Teaches

Geology fans will enjoy these questions.

How pillow lava forms
Why it has glassy rinds
Where it forms today
Where to see it on land
What it tells geologists

Did You Know?

Pillows can be a meter across.
Sediment fills gaps between pillows.
Submersibles explore ridge pillows.
Some ancient pillows are billions of years old.
Steam bubbles rise as lava cools.