Explore - Mars: Inside and Out! - Setting the Scene

Puzzling Patterns - Where Does Volcanism Occur?


Children ages 8 to 13 compare volcano maps of Earth and Mars and identify patterns, similarities, and differences in this 30 minute activity.

What's the Point?

  • Volcanos on Earth tend to occur in long chains, either along continental edges or in the ocean.
  • There are fewer, larger volcanos on Mars, compared to Earth, and they are grouped in a few regions.
  • The surface features of a planet provide clues to their internal processes.
  • Geologists use comparisons between features on Earth and other planets, like Mars, to help them identify differences in how the features may have formed or changed.


For each child:

For each team of 3 to 4 children:

For the Facilitator:


1. Provide the teams with copies of the maps of Mars and Earth without the volcanos marked, and invite them to examine the maps.
What do they observe on the different maps? Answers will vary and may include that the Earth has water and land and Mars has no oceans; there are volcanos, Mars has more craters, etc.

2. Ask the children if they see any volcanos on the map of Mars. Invite them to place a dot on top of each volcano they see.

  • What do the volcanos look like? Circular shapes that have a high peak. They may have a caldera in center, a bowl shaped "hole." Remind the children that these images are from space, and what may look like a small feature from space could actually be very large.
  • Can they find Olympus Mons on Mars? It is the tallest, widest volcano on Mars.

3. Invite the children to examine the map of Earth more closely. The Earth map and the Mars map are not to the same scale.

  • Do they see any features that look like the volcanos on Mars? Probably not.
  • Does Earth have active volcanos? Absolutely — the children may be familiar with the Hawaiian islands and Mount St. Helens in Washington. Help the children find Mauna Kea in the Hawaiian volcano chain.
  • Why might volcanos be hard to see on this map of Earth? Because, at this scale, the volcanos are very tiny!

4. Provide the children with the maps of Earth and Mars with the volcanos marked.

  • What does the map of Earth show? Where active or historically active volcanos occur.
  • How does the number of volcanos the children identified on the other map of Earth compare with this map? There probably are many more volcanos on the volcano map than the children were able to identify.
  • How does the number of volcanos the children identified on the other map of Mars compare with the map of volcanos on Mars? They probably identified most of the volcanos on Mars. They probably identified most of the volcanos on Mars.

5. Have the children make observations about the volcanos on Mars compared to Earth. Invite them to take notes of their observations about the number, size, shape, and patterns of the volcanos on the different planets.

  • Which has more, Earth or Mars?
  • Where are the volcanos bigger? What do they recall from building the volcanos?
  • Do they notice any pattern to the volcanos? Do they make particular shapes? Are they located in particular places?

6. Once the teams have completed their observations, bring them back together as a group to discuss their findings.

  • Which has more volcanos, Earth or Mars? Earth.
  • What do they notice about the sizes of volcanos on the two planets? Mars' volcanos are larger.
  • Do they notice any pattern to the volcanos on Earth? Do they make particular shapes? Are they located in particular places? Many of Earth's volcanos follow the edges of the continents and make lines — chains — of mountains. Some are in the middle of the ocean and also may be in chains.
  • Do they notice any pattern to the volcanos on Mars? Do they make particular shapes? Are they distributed across the planet, or in one general location? The volcanos on Mars are very close to one another in relation to the entire surface area of the planet.
  • Do you observe any long chains of volcanos on Mars, like the ones you noticed on Earth? No. While Mars volcanos are close to one another, and a few of them appear to be in a line, they do not form "long chains" of volcanos like on Earth.
  • What does it tell us about a planet if it has volcanos? That it is — or was — hot on the inside — hot enough to melt rock and make magma and lava!
  • Do they have any evidence that Earth's volcanos are active? Yes! Volcanos are erupting on Earth all the time!
  • What about Mars? No, we do not have any evidence that volcanos are active because we have not ever observed an eruption. However, some volcanos on Mars are considered by scientists¬† to have erupted recently because the surfaces of the volcanic flows have few craters. This suggests that they are young, fresh, surfaces. Planetary scientists estimate that these volcanos were active in the last 10 million to 100 million years. To a scientist, this is practically yesterday! Earth is 4.5 billion years old; 100 million years is within the last 2% of solar system history!


Have the older children ponder why the differences they observed between the volcanos on Earth and Mars might happen. What are their ideas? They will undertake an activity that shares one of the reasons that the Mars volcanos are so large! Allow a few minutes for the children to record their ideas in their GSI Journal.

For a more extensive data-rich inquiry activity in which children explore the processes that occur at plate boundaries (volcanos, earthquakes, formation and destruction of the sea floor, and the related physical features), please see Discovering Plate Boundaries.