COPENHAGEN, Denmark — Ask any youngster in school and they can probably tell you Mount Everest is the planet’s tallest mountain. However, they may not know that the “roof of the world” has actually gotten quite a bit taller over time. A new study finds Tibet, the world’s highest region, now sits about 2,000 feet higher than it did in the distant past.
Researchers from the University of Copenhagen say underwater lava held the geological clues to these new revelations about Earth’s evolution. Tibet’s title as the roof of the world is well deserved. The mountainous region sits just shy of 15,000 feet above sea level. The Himalayan mountain range is also home to the planet’s two highest peaks, Everest and K2.
However, the area’s actual height has stirred up debate among scientists for years. Study authors explain that some researchers believe the area has been at the same height for most of its existence. On the other hand, others suspect Tibet has continued to grow taller over millions of years.
Using fresh scans of the Indian Ocean seabed and calculations of the movement of Earth’s tectonic plates, the new study finds evidence the famous mountain range has experienced a “growth spurt” since its formation.
“By looking at older data of Tibet’s emergence and combining it with new geological data from the Indian Ocean, we are pretty certain that there was a major geological change in Tibet about 15-18 million years ago, one that caused the wide area to rise between 300 and 600 meters,” explains Associate Professor Giampiero Iaffaldano in a university release.
A head-on collision between China and India holds the answer
Study authors say this 1,000-2,000-foot increase is due to the tectonic plates which modern day India and China sit on. In the past, India was much further south, but its plate slowly moved north over millions of years. Eventually, the team says this plate collided with China and formed Tibet.
Scientists who believe the region is still the same height say plant fossils and rock samples prove the area has not changed in 30 million years. However, those saying the area continued to grow point to the long time it took India and China’s plates to stop after their collision. This “decelerating collision,” some scientists believe, pushed Tibet upwards by over a mile throughout the years. Oddly enough, Iaffaldano says the truth appears to sit somewhere in between both theories.
“What the study contributes to, is actually a combination of the two previous hypotheses, different data sets and conclusions. What I’ve done is take a closer look at the speed of the India-China collision using Indian Ocean geological data that has only recently become available to the public,” the lead author says.
Earth’s magnetic polarity provides a vital clue
Study authors add that the lava which the planet spits out onto the ocean floor gave them a vital clue about Earth’s evolution. This lava acts as a record of the shifts in Earth’s magnetic polarity, the direction of the planet’s north and south poles.
Throughout history, this polarity has reversed itself several times, as in north becomes south and and vice-versa. Luckily, scientists also know when these shifts have occurred and can actually trace a tectonic plate back to a certain point in time based on lava’s magnetization.
“A closer look at this type of data held the answer to the question of whether Tibet has gotten higher or not. It has proven tremendously useful to calculate the speed of India’s collision with China from geomagnetic data. More and more of such data, often originally collected for purposes other than fundamental scientific research and thereby not publicly available, is now being released and used by scientists,” Iaffaldano explains.
“This new knowledge about Tibet is important for better understanding of Earth’s evolution and the methods used could turn out useful in future studies.”
The study appears in Geophysical Journal International.