What is a Hotspot?

This diagram shows how the plate pulls the islands away from the hotspot after they are formed. Sourced from the Galapagos Conservation Trust.

The Galapagos Islands were made from volcanoes that are under water. They are from a hotspot, or a crack in the earth's crust. There are other islands, such as Hawaii, that were also made by hotspots.

Fernandina Island is the youngest of all the islands. It is covered in rope-like black lava rock. Photo by Alison Travis

The top layer of the earth is called the crust. This is the part of the earth we live on. The crust is not one smooth piece. It is broken into pieces called plates. It looks like a hard-boiled egg if you cracked the shell all over.

Under the crust is the mantle. It is full of very hot melted rock called magma. Magma can come up through the cracks between the plates. This makes a volcano. When the magma flows out of the volcano, we call it lava. The lava cools from the water and air. It turns into hard black rock. If there is enough lava from a hotspot, the rock peeks up out of the water and we can walk around on it as an island.

There are 19 islands in the Galapagos because the plate is moving. It moves very slowly. It only moves about 2 inches each year. That is about the length of an adult's finger. When the volcano erupts, the lava makes an island. Then the plate moves, so the new island is pulled away from the hotspot. When the crack makes a new volcano that erupts, it makes a new island. Then the plate pulls the islands away from the hotspot again.

All the islands are moving to the east. Once each island is pulled away from the hotspot, the volcano on that island cannot erupt any more. The oldest islands were made by the hotspot a long time ago. They are now on the east side, far away from the hot spot. They were made about 4 million years ago. The youngest islands were made by the hotspot less than 1 million years ago. The newest islands are on the west side and are still close to the hotspot. 

The old islands to the east are very different than the new islands to the west. How do you think they are different? Well, it takes a long time for plants to grow out of lava. The old ones have had more time. Also, they do not erupt any more. So, they are green and have more animals. The new islands are flat, black, and dry.

On my expedition, I got to see islands on the east and the west. Can you guess if I am on an older or newer island in these pictures?

Ms. Travis on Santa Cruz Island with giant tortoises in the wild. Photo by Stacy Gasteiger

Ms. Travis on a beach on Isabela island. Photo by Stacy Gasteiger

Read the captions below the photos and check this map to see if you were right. Remember, islands to the east are older and islands to the west are younger.