Imagine a world where mountains grow so high that they pierce the upper atmosphere, forming a rocky labyrinth for the pilots.
Maybe this world exists somewhere in the distance of the universe. But on Earth, mountains can not grow much higher than Mount Everest (19459004), which extends over 8,840 meters above sea level.
So what prevents the mountains of our planet from growing forever?
There are two major factors that limit the growth of the mountains, said Nadine McQuarrie, a professor of geology and environmental science at the University of Pittsburgh.
] The first limiting factor is gravity . Many mountains form due to movements in the Earth's surface known as plate tectonics . This theory describes the earth's crust as mobile and dynamic, divided into large pieces that move with time. When two plates collide, the impact forces the material upward from their contacting edges. This is how the Himalayan mountains in Asia came to be, which also includes Mount Everest.
Related: Which mountain is the highest in the world?
The plates continue to contract and the mountains continue to grow until it becomes "too heavy to do this job against gravity," McQuarrie told Live Science. At some point the mountain becomes too heavy and its own mass stops the upward growth caused by the crunching of these two plates.
But mountains can also be formed in other ways. Volcanic Mountains like the Hawaiian Islands are formed of molten rock that erupts through the crust and begins to pile up. But no matter how mountains are formed, they eventually become too heavy and succumb to gravity, McQuarrie said.
In other words, if the earth had less gravity, its mountains would grow taller. That's what happened on Mars, where mountains tower much higher than our planet, McQuarrie added. The Mars Olympus Mons, the highest known volcano in the solar system, is 25,000 m high, almost three times as high as Mount Everest.
Most likely, because Mars has low gravity and high eruption rates, the lava flows on Mars remained much longer than ever (or ever before) on Earth (1
The second limiting factor for the growth of mountains on Earth are rivers. At first glance, rivers make mountains appear higher – they cut into the edges of the mountains and erode material, creating deep crevices near the foot of a mountain. "All those really tall, beautiful, dramatic peaks are actually a bit lower than the plateau itself," said McQuarrie. But when rivers drain away, their channels can become too steep. This can trigger landslides that carry material away from the mountain and limit its growth, she added.
A group of researchers recently suggested that rivers reach a "threshold slope" after which their impact on the growth of a mountain is limited by erosion in a study published on September 16 in the journal Nature Geoscience is.
Underwater mountains are similarly limited by gravity and landslides, but they can become much higher than the mountains on land because the higher density water supports them more against gravity than air, McQuarrie said. "Water provides lateral support to the sides of these mountain ranges so they are higher," she said.
Everest is often referred to as the highest peak on earth, but there are other nominees for the title "Highest Mountain in the World". Mauna Kea, an inactive volcano in Hawaii, is the highest mountain in the world, measured from its base – which lies deep in the Pacific Ocean – to its summit. It measures 33,500 feet (10,210 m), slightly higher than Everest. However, the base of Mauna Kea is 6,000 meters below sea level and the summit is 4,205 meters above sea level. Measuring from sea level, Mount Everest is more than twice as tall as Mauna Kea and the Everest summit is the highest point in the world.
Originally published on Live Science .