What are the oldest mountains in the world? How can scientists determine their ages?

Stunning view of the Himalaya mountains (Cholatse and Taboche to the left), Ngozumpa glacier, and Gokyo lakes (the world's highest freshwater lakes, sacred for both Hindus and Buddhists), as seen on top of Gokyo Ri (5,357 m), near the village of Gokyo, in Sagarmatha National Park, UNESCO World Heritage Site in Khumbu region, Solukhumbu district, eastern Nepal, Asia.

The mountains may look old, but some of them are still young, while some are very old from a geological point of view. So, what is the oldest mountain range? And what about the latest?

In general, taller mountain ranges like the Himalayas tend to be more recent, while shorter peaks that have gone through thousands of years of erosion like the Appalachians in northeastern North America are often older, according to the museum . American Natural History Center in New York City, but due to the constantly changing topography of the land, this is difficult to define and requires an understanding of how these peaks have survived and eroded over time.

In the report published on February 6, Live Science states that today's landscapes are characterized by active and dormant mountain ranges and are subject to billions of years of transformation, which is why it is difficult to determine the age of these peaks, according to Jim Van Orman A geochemist at Case Western Reserve University in Ohio, USA.

Most mountain ranges are formed by tectonic plates, the giant puzzle-like plates that slide over the Earth's mantle. Over millions of years, the movement of different tectonic plates causes entire mountain ranges to rise to great heights.

Tectonic plates

There are two main types of tectonic boundaries, at convergent boundaries, where tectonic plates collide. The collision often causes the less dense plate to slide, or to descend down and into the main mantle below the other plate, and this sinking crust can lift the Earth and lead to the emergence of mountain ranges Huge, like the Himalayas that includes Mount Everest, Van Orman said.

On the other hand, divergent boundaries form where tectonic plates separate. As the plates move away from each other, the crust expands and becomes thin, and hot magma rises to fill the gaps that have formed, forming mountains and valleys such as those in the Basin and Range region in the western United States and northwest Mexico .

The history of the mountains

There are a lot of nuances when it comes to determining the ages of mountain ranges. Take the Appalachian Mountains, for example. The mountain range began rising from convergent boundaries about 470 million years ago, and grew the longest starting from about 270 million years ago when the continents collided that eventually became North America and Africa, according to the US Geological Survey.

Over the following millions of years, erosion eroded their original height. The mountains we know today are thanks to the subsequent rise that restored their height.

This rise and fall in altitude - which is a distinctive feature of the mountains - makes it difficult and subjective to determine the actual age of the mountain ranges, as Van Orman says - in an interview with Live Science - that the Appalachian Mountains "have a complex history, there is the age of the original rocks, but they were not A mountain range when it has been delineated [or eroded] for much of its history. So, how old is it?"

Measuring tools

While tracking the timeline of a mountain range is difficult, geologists have tools for measuring the age of mountain formations depending on the type of rock. When igneous and metamorphic rocks form, they generate minerals, radioactive isotopes, or different forms of elements that contain different numbers of neutrons. In its nucleus, which can be dated.

For sedimentary rocks, researchers use evidence stuck in rock layers, such as fossils or volcanic ash, to gauge the age of the rocks. Eroded mountain sediments that end in nearby sedimentary basins can also be appropriately traced back to their origin and date, Van Orman says.

Through these measurements, geologists can attribute a spectrum of relative ages to some of the Earth's mountainous terrain; On the older side, the Makhonjwa Mountains in South Africa, which range from 600 to 1,800 meters in height, contain rocks that are 3.6 billion years old, according to NASA's Earth Observatory .

It is also possible that other ancient plates that form the cores of continents, called kratons, were once part of mountain ranges, and can be found in Greenland, Canada, Australia and beyond.

What are the newer mountains?

There are other mountain ranges dating back to a more recent geological history, for example, the range in the "basin and chain" region, such as the "Snake Range", began to appear about 30 million years ago, and individual volcanic mountains appeared during The past million years, like Mount Parícutin, emerged unexpectedly from a cornfield during a 1943 volcanic eruption in Mexico, according to the Smithsonian National Museum of Natural History.

Geologists are still researching when and how Earth's various mountain ranges formed. Exploring these challenging timescales can convey insights into past global climate and biodiversity, as these massive peaks affect air circulation and genetic exchange.

"It helps reconstruct the entire history of the Earth," says Van Orman. "Going back in time, the only real evidence we have of [plate movement] is to look at these ancient mountain sheaves."