Why aren’t there mountains that are 10 or 15 miles high on Earth?

Question

Mt Everest is just under 5.5miles high. Olympus Mons on Mars is 16 miles high. Why aren’t there much larger mountains on Earth? What’s the highest a mountain can go on Earth?

In: 4987

Answer 1

The size of mountains on a planet is influenced by several factors, including the planet’s gravity, crust composition, tectonic activity, and erosion processes. Here’s a breakdown regarding Earth and Mars:

1. Gravity: Earth’s gravity is stronger than that of Mars. A higher gravitational force will tend to pull tall structures (like mountains) down, limiting their maximum height. In contrast, Mars, with its weaker gravity, allows for taller structures to exist.

2. Plate Tectonics: Earth’s crust is broken into tectonic plates that move around on the semi-fluid asthenosphere below. Mountains on Earth, especially the tallest ones like Everest, are formed by the collision of these plates. Once mountains reach a certain height, the crust can begin to flow outwards, and the gravitational forces pushing downwards can prevent the mountain from growing taller.

3. Erosion: Earth has a dynamic climate with rain, wind, snow, and ice, all of which contribute to the erosion of mountains. Over time, these processes wear down the mountains, limiting their height. Mars, on the other hand, has a much thinner atmosphere and lacks the liquid water that’s so abundant on Earth, so erosion from these processes is significantly reduced.

4. Crust Composition: The crustal composition can influence a mountain’s height. For instance, the presence of certain rock types can support taller structures, while others might not.

5. Isostasy: This is the concept of Earth’s crust “floating” on the semi-fluid mantle below. When mountains form, the crust is pushed downwards into the mantle to compensate. Over time, this can limit the height of the mountain.

As for the maximum height a mountain can reach on Earth, it’s a complex issue and depends on various factors, including the ones listed above. One hypothesis, known as the “theoretical maximum height,” suggests a limit of around 10 km (or about 6.2 miles) due to the principles of isostasy and the material properties of the Earth’s crust. However, this is a rough estimate and could change with new discoveries or insights….