Question

Suppose we were to make the following discoveries. (These are not real discoveries.) In light of your understanding of Mars, decide whether the discovery would be considered plausible or surprising. Explain clearly; because not all of these have definitive answers, your explanation is more important than your chosen answer. We discover a string of active volcanoes in the heavily cratered southern highlands.

Short answer

The discovery is surprising because active volcanoes are unexpected in the ancient southern highlands of Mars.

Step-by-step solution

Understanding the Discovery

The discovery describes finding a string of active volcanoes located in the heavily cratered southern highlands of Mars.

Geological Context of Mars

Mars has large volcanic features such as Olympus Mons and Tharsis Montes, which are found in the northern hemisphere and are believed to be extinct.

Characteristics of the Southern Highlands

The southern highlands of Mars are known to be older and more cratered, indicating that they have not been geologically active for a long time.

Assessing Plausibility

Considering that the southern highlands are heavily cratered and not known for recent volcanic activity, discovering active volcanoes here would be surprising.

Explanation

Active volcanoes are more likely to be found in regions of Mars that have shown geological activity, such as the areas around Tharsis or Elysium. Hence, activity in the southern highlands would go against current scientific understanding.

Key concepts

Martian volcanoes

Mars is home to some of the largest volcanic structures in the solar system. When we think of Martian volcanoes, names like Olympus Mons and Tharsis Montes often come to mind. These volcanic giants are located in the planet's northern hemisphere, primarily in the Tharsis region. Olympus Mons, in particular, is the tallest volcano and mountain in the solar system, standing about 13.6 miles (22 kilometers) high, over twice the height of Mount Everest.

However, these volcanoes are believed to be extinct. Scientists suggest that volcanic activity on Mars ceased millions of years ago. This makes the idea of discovering active volcanoes on Mars both fascinating and unexpected. Imagining a string of active volcanoes elsewhere, like in Mars' southern highlands, would indeed surprise scientists, as it contradicts what we currently understand about Martian geology.

On Earth, volcanoes are closely linked to tectonic activity and the movement of crustal plates. Mars does not have the same plate tectonics; instead, its volcanic activity was likely due to thinning of the planet's crust over hot spots.

Southern highlands

The southern highlands of Mars are one of the planet's most striking features. They contrast sharply with the smoother, lava-deposited northern plains. These highlands are heavily cratered, indicating their ancient age. In fact, they are considered some of the oldest terrains on Mars, with formations dating back to the Noachian period, more than 3.7 billion years ago.

The cratered nature of the southern highlands tells a story of a time when Mars was bombarded by meteorites. Since newer impacts have created numerous craters, it suggests that there has been little geological activity to resurface the region. The lack of young lava flows in the southern highlands supports this idea.

• Heavily cratered landscape
• Ancient geological formations
• Lack of current volcanic activity

Therefore, a discovery of active volcanoes in this region would be intriguing and would challenge existing geological models.

Understanding the relationship between these ancient terrains and Mars's overall geologic history could provide crucial insights into the planet's past and future activity.

Geological activity on Mars

Mars has a long and complex geological history. Geological activity, such as volcanic eruptions, tectonics, and crustal movements, played a significant role in shaping the planet. In the past, Mars was a much more dynamic planet, with active volcanoes and possibly liquid water flowing on its surface.
Today, Mars appears to be geologically inactive for the most part. The northern hemisphere, home to expansive volcanic plateaus and ancient lava plains, along with formations like Valles Marineris, suggests a history of significant geological events.

Key features of Martian geology include:

• Volcanism, especially around the Tharsis and Elysium regions
• Different ages in surface features across the planet
• A lack of plate tectonics

Recent research hints at the possibility of minor tectonic activity or "marsquakes," but nothing has confirmed widespread geological activity as seen in Earth's past.

If contemporary volcanic activity were discovered, particularly in unexpected regions like the southern highlands, it would revolutionize our understanding of Mars. It might suggest internal heat sources or processes at work that we have yet to discover or understand.