Why are there no mountains above 10 km?

Description: The article reveals the reasons why there are no mountain peaks more than 10 kilometers high on Earth. Geological, tectonic and physical factors, as well as the role of gravity and erosion, are considered. The material is aimed at a wide audience and written in a popular science style.




Introduction
The land is famous for its diverse terrain: from coastal plains to mountain ranges beyond clouds. But even the highest mountains on the planet - such as Everest (about 8,849 m above sea level) and K2 (about 8,611 m) - are still far from the symbolic mark of 10 kilometers. Many lovers of geography and just curious people are concerned about the question: why there are no mountains on Earth above this conventional "bar"? After all, seemingly moving tectonic plates, forming mountain ranges, could “grow” the tops larger. However, it turned out that there are quite clear physical, geological and even climatic reasons for this.

In this article, we will look at the main factors that limit the growth of mountain ranges on Earth, and learn why, despite millions of years of tectonic activity, mountains still do not break the cherished mark of 10 kilometers. At the same time, we will touch on the comparison with other planets, because, for example, on Mars there is Mount Olympus with a height of more than 20 km - and this suggests interesting reflections on how gravity and the internal structure of the planet affect the maximum "architecture" of the relief.

Main part

1. Tectonic processes: the engine of mountain growth
Mountains are the result of collision and interaction of lithospheric plates. When two continental plates converge, their edges crumple, pushing layers of rock upwards and forming mountain systems – say, the Himalayas emerged from the collision of the Indian and Eurasian plates. Tectonic activity lasts millions of years, and theoretically, it would seem, mountains can grow indefinitely, because the collision process does not stop. But in practice there is a limit due to several factors.

• Rheological properties of rocks. Deep beneath the Earth’s surface, temperatures and pressures increase, making rocks more “plastic.” Upon reaching a certain height and mass, the “root” of the mountain (its underground part) begins to flatten, settle into the mantle, losing the ability to “hold” additional height.
• Isostasis. This is the principle that the lithosphere floats on the semi-liquid asthenosphere like an iceberg in water. The higher the mountain, the deeper its root part goes under the surface. As a result, the growth of the summit faces an “isostatic equilibrium” – the rocks at the bottom begin to penetrate into softer layers, preventing further rise.

Thus, the growth of mountain ranges is both the result of colossal tectonic forces and their own vulnerability to the internal balance of the planet. Even if outwardly the mountains still seem “young” and growing (the Himalayas rise a few millimeters a year), they also gradually settle due to the turmoil and partial melting of rocks in the depths.



2. Gravity and strength of material
Gravity plays an equally important role. Gravity pulls all objects to the center of the planet, including giant mountains. If a structure (in this case, a mountain structure) exceeds a certain critical height, its own mass becomes so large that the "base" (the underlying rocks) begins to collapse.
Key points:

• Rock strength. Every breed has its own limit of strength. At a certain pressure and temperature, the rocks go into a plastic state or experience deformations (faults, folds), which interfere with the stable growth of the top.
• Stress at the base of the mountain. The higher the mountain, the more weight falls on its base. This intensifies tectonic faults and causes "sprawl" of rocks.

Therefore, for example, on Mars, Mount Olympus can rise 22-25 km above the surrounding surface. In the lower gravity of the Red Planet, such giant structures are stable, but on Earth such a height would be simply unattainable - the rocks would break under such a load.

3. Erosion and Climate “Destructive Power”
Even if we take into account that tectonic processes can theoretically create huge mountains, in practice, erosion constantly “eats” the tops. Wind, rain, glaciers and temperature changes contribute to limiting mountain growth.

• Wind and rainfall. Daily weather conditions destroy the upper layers of rocks, carry small particles. Over time, this process can “make” a significant part of the heights.
• Glaciers. In cold regions, mountain ranges are “undermined” by glaciers, which, slowly moving down like giant “sandpaper discs”, cut and polish the peaks.
• weathering. Fluctuations in temperature lead to the formation of cracks into which water penetrates. Freezing, it expands and over time breaks off pieces of rock, weakening the structure of the mountain.

Of course, erosion and gravity do not work instantly, but over thousands and millions of years. But it is they who prevent the tops from continuing to grow indefinitely: “What has grown, then wears away.” As a result, a dynamic equilibrium is established between tectonic “rise” and atmospheric “smoothing”.

4. Examples of “high ceilings” on Earth
verest. The highest point on Earth above sea level (about 8,849 m). Geologists say that Everest is still rising due to the constant movement of the Indian plate, but at an extremely slow pace. At the same time, climatic conditions and erosion stabilize the result, preventing the mountain from becoming much higher.
andes. Here the highest peaks are Aconcagua (6962 m), Huascaran (6768 m). Despite the intense tectonic activity (the junction of the Nazca and South American plates), there is nothing higher than 7 km in the Andes, and this is the result of the balance between growth and “knocking” of the peaks.
Pamir and Tian Shan. The peaks of Communism (7,495 m) and Victory (7,439 m) are also in the zone of active tectonics. However, erosion processes there are very strong (sharp temperature changes, glaciers). As a result, the height does not exceed 8 km.
In all these examples, we see that the ceiling is just below 9 km (with rare exceptions, such as Mount Everest, which approached 8.8-8.9 km). And this is not accidental, but the result of a set of factors discussed above.



5. "What about the other planets?"
It is worth mentioning the planetary features. On Mars, as already mentioned, is Mount Olympus (Olympus Mons), considered the highest mountain in the solar system (if you count the height of the surrounding surface). It rises more than 20 km and has a diameter of about 600 km. Why is there such a height?

• Low gravity.. Mars is much smaller than Earth and its gravitational pull is weaker. Accordingly, giant volcanic structures may not collapse under their own weight.
• Fewer atmospheric effects. Mars has a thin atmosphere, lower water activity, almost no liquid precipitation, so erosion is slower.
• Single-point volcanism. Olympus is a giant shield volcano that “feeds” from a single hot spot, without being displaced by tectonic plates (which, it seems, do not exist on Mars). On Earth, the lithosphere moves, and volcanic foci “move”, forming chains of volcanoes, rather than one giant.

Thus, the special conditions of Mars (low gravity, weak climatic "wear and tear", the absence of mobile plates) allow you to "grow" a mountain much higher than on Earth. This clearly shows that the height of mountains on the planet is not a universal constant, but the result of the interaction of many geological and physical factors unique to each space environment.

Conclusion
Mountains above 10 kilometers on Earth are not found due to a combination of several reasons: tectonic restrictions associated with isostasis and plasticity of rocks under high temperature and pressure; gravity, which causes the destruction and subsidence of the base of mountains; and intense erosion, “eating” the tops. All these processes establish a kind of “ceiling”, above which the mountain structure can not stably exist.

Although you can sometimes hear romantic hypotheses about mountains 15 or 20 km, the real geological picture proves that such an altitude for the Earth is impossible: materials simply can not withstand the gravitational load, and atmospheric and climatic impacts will inevitably collapse the tops. Therefore, the Himalayas with its “peak of the world” – Everest – are close to the limit that the planet can “allow” in the current geophysical conditions.

Meanwhile, we see examples on other planets (Mars, Venus) where the conditions and gravity are different - higher mountains may exist there. This fact clearly demonstrates that the topography of the planet is directly related to its internal structure, gravity, atmosphere and history of tectonic processes. The question “Why are there no mountains above 10 km?” is not only geographical, but also astronomical. To understand the Earth, we compare it to other planets, and vice versa.

In any case, a high ceiling for mountains or not, the nature of the Earth is generous enough to give us stunning landscapes and Gothic peaks 8-9 km high, to the tops of which it is unlikely that most people will climb even once in a lifetime. And, perhaps, their uniqueness and impressiveness are manifested largely due to the fact that nature, by its laws, has set a clear limit.

Glossary

• lithosphereThe outer solid shell of the Earth, consisting of the Earth's crust and the upper part of the mantle. Divided into tectonic plates.
• IsostasisEquilibrium between areas of the lithosphere "floating" on the denser asthenosphere. The analogy is an iceberg in water.
• erosion: the process of destruction of rocks under the influence of wind, water, temperature changes and other factors.
• Asthenosphere: the layer of the upper mantle of the Earth, which is in a semi-melting state, on which lithospheric plates “float”.
• Gravity.The force of attraction arising from the mass of the planet and acting on objects on or near it.
• Rheological properties: characteristics of materials (rock), describing their behavior during deformation (solid, plastic, liquid).
• Olympus Mons (Olympus)The largest volcano mountain in the solar system, located on Mars and reaches 22-25 km in height.
• Shield volcano: a type of volcano with gentle slopes, formed from fluid lava; has a huge size and a small angle of inclination.