Brand-new land · Chimney VolcanoScience for kids

How do volcanoes make new land?

In short: When lava flows into the sea, the cold water makes it harden quickly into new rock, so the coastline grows a little. The islands of Hawaiʻi were built this way by undersea eruptions, and the Island of Hawaiʻi is still growing.

How it works

An undersea volcano erupts again and again, piling lava layer on layer on the sea floor, like stacking building blocks under water. When the pile gets tall enough, its top breaks the surface and a new island is born. Every one of the Hawaiian islands started out this way.

When lava reaches the shore and meets cold seawater, huge clouds of white steam billow up. The lava cools and hardens into new black rock, pushing the coastline out a little further. Some of the lava shatters in the water into black sand.

Under Hawaiʻi there is an extra-hot area called a hotspot, where magma keeps rising. The Pacific Plate moves slowly over it like a conveyor belt, carrying older islands away while new ones grow above the hotspot. That's why the islands get older towards the northwest.

Where to see it in New Zealand

New Zealand has brand-new land too. Rangitoto Island, in Auckland's Hauraki Gulf, erupted out of the sea only a few hundred years ago and is Auckland's youngest volcano. Where there was once open water, there's now an island with forest growing on its black lava. You can visit it by ferry.

Try it together

Pour a little water into a shallow tray. With a spoon, drop thick mud or wet sand onto the same spot again and again, each spoonful landing on the last. How many spoonfuls does it take for your 'undersea volcano' to poke above the water and become an island?

Kids also ask

Where does life on a new island come from?

Seeds and spores blow in on the wind, wash up with the waves, or hitch a ride on birds' feathers and feet. Insects and birds fly in too. Slowly, bare lava comes to life.

Have any islands formed recently?

Yes. Surtsey, off the south coast of Iceland, rose from the sea during an undersea eruption in the 1960s. Scientists have been studying how plants and animals arrive there ever since.

In the game, “Brand-new land” is a nature card on Chimney Volcano.

Your child finds this card by reaching the right place or meeting the right weather on the island, and lights it up by answering the question on the back. Tap the button below and the game shows your child which island it is on and how to find it. Mochi Isle is a browser learning game for ages 5 to 18; the main island and the daily lesson are free.

Find “Brand-new land” on the island ↗ All cards from Chimney Volcano