Classroom lesson 路 Giant granite boulders馃嚫馃嚚 Seychelles

Giant granite boulders

Smooth grey rocks the size of houses sitting on the beach

Huge smooth grey granite boulders on a white-sand beach at Anse Source d'Argent

Photo 路 Wikimedia Commons

What is it?

On the inner islands of Seychelles, especially on La Digue and Praslin, the beaches are dotted with enormous smooth grey boulders. Some are as big as a small house, sitting in the sand or half in the sea. They are made of granite, and they are older than almost everything else around them.

Tell me more

Granite is a very hard, sparkly rock that usually forms deep underground when hot melted rock cools down slowly. The boulders of Seychelles were made this way around 750 million years ago - long before there were any animals on land, never mind dinosaurs. They are some of the oldest rocks you can ever stand on at the seaside.

For hundreds of millions of years, rain, wind and waves have slowly polished these boulders smooth. The corners have been rubbed off. Now they sit like sleeping giants on the beach, often with a small bushy tree growing out of the top.

The most famous beach for boulders is called Anse Source d'Argent on La Digue. It looks so unusual that it is often called one of the most beautiful beaches in the world. Tourists from many countries come just to see the way the boulders meet the white sand and the turquoise sea.

Children growing up in Seychelles climb on the boulders, jump off them, and find hiding spots between them. They warm up in the morning sun, so by lunchtime they are toasty against your back. A boulder makes a brilliant lookout point for spotting fish in the shallow water below.

In the classroom

Walk your class through this in 15 minutes.

Talk together

Discussion prompts

  1. 01Why might rocks at the beach become smooth and round over time? What is doing the polishing?
  2. 02What is the oldest thing you have ever touched? How old do you think it was?
  3. 03If you could climb the biggest boulder in your area, what would you do up there?
Try this

Classroom activity

Find a small stone outside. As a class, time how long it takes to make it shinier by rubbing it gently with another stone. Now imagine the wind and rain doing the same job for 750 million years. Discuss: what would your school playground look like in that much time?