The Dynamic Rise of Mount Everest: How the Arun River Influences the World’s Tallest Peak
Context:
A new study published in Nature Geoscience has shed light on an intriguing factor contributing to Everest’s rise; the erosion caused by the nearby Arun River.
More in the News:
- Mount Everest, known as Chomolungma in Tibetan and Sagarmatha in Nepali, stands at a staggering height of 8,849 meters (29,032 feet), making it the tallest mountain in the world.
- While its height has been a subject of fascination for climbers and scientists alike, recent studies reveal that Everest is not only tall but also continuously growing.
About Plate Tectonic Theory and Its Contribution to Mount Everest’s Rise:
Formation of the Himalayas:
- The Himalayas, including Mount Everest, were formed approximately 50 million years ago due to the collision of the Indian and Eurasian tectonic plates.
- This tectonic activity continues to be a primary driver of elevation in this region.
- As these plates converge, they create immense pressure that forces land upwards, contributing significantly to the mountain’s height.
Continuous Geological Activity
- While plate tectonics remains a major factor behind Everest’s formation and continued growth, recent findings suggest that additional geological processes are at play.
- The merging of river systems, particularly around 89,000 years ago when the Arun River joined with the Kosi River network, initiated increased erosion and altered sediment transport dynamics in the area.
Recent Findings: How Rivers Influence the Height of Mount Everest
The researchers utilised numerical models to simulate river evolution and its geological impacts, leading to significant insights into how rivers can influence mountain formation in the following reasons:
- Continuous Elevation Factors: Mount Everest’s continuous elevation is not solely due to tectonic activity but also by geological processes such as isostatic rebound.
- This phenomenon occurs when land masses rise due to the removal of weight from the Earth’s crust.
- As erosion from rivers like the Arun reduces surface weight, the crust beneath can adjust and rise accordingly.
- This process reveals a fascinating interplay between erosion and uplift that has puzzled scientists for years.
The Role of Isostatic Rebound:
- Isostatic rebound can be likened to a boat rising in water when cargo is unloaded.
- When heavy materials like ice or eroded rock are removed from the Earth’s crust, the land beneath slowly rises in response.
- In the case of Mount Everest, this process has been enhanced by changes in river systems over millennia.
Erosion Dynamics:
- The recent study indicates that as rivers like the Arun flow through mountainous terrains, they erode substantial amounts of rock and soil from their banks.
- This erosion diminishes pressure on the underlying mantle—a semi-liquid layer beneath the Earth’s crust—allowing it to push upward more easily.
- The study also highlights that the loss of landmass in the Arun River basin, located approximately 75 kilometres away from Everest, is causing the mountain to rise by up to 2 millimetres each year.
- Over the past 89,000 years, this erosion has contributed to an increase in Everest’s height by approximately 15 to 50 meters.
The Impact of River Erosion:
- The study estimates that isostatic rebound accounts for about 10% of Mount Everest’s annual uplift rate.
- This means that as material is washed away by river flow, it not only contributes to immediate changes in landscape but also facilitates long-term geological adjustments.
The Process of Drainage Capture:
- The research also discusses a process known as drainage capture or “river piracy.”
- Approximately 89,000 years ago, when the Arun River merged with other rivers in Tibet, it significantly increased its erosive power.
- This merger allowed more water to flow through the Kosi River system, enhancing its ability to carry away sediments and rock from surrounding areas.
Conclusion: The Dynamic Nature of Earth’s Surface
While Mount Everest’s towering presence has long captivated climbers and geologists alike, understanding its growth offers deeper insights into geological processes influencing our planet. As scientists continue to explore these relationships between rivers and mountains, they reveal not just how mountains rise but also how they are shaped by various environmental factors over time. The ongoing study of Mount Everest serves as a reminder that even seemingly stable features on Earth are subject to change driven by natural forces—an ever-evolving landscape shaped by both tectonic activity and hydrological dynamics.