In 1903, Theodore Roosevelt said that if American citizens were to see just one natural wonder in their lives, they should visit the Grand Canyon in Arizona.
The liquid sandpaper of the Colorado River has carved a unique glimpse into the geology of the last two billion years. But even though most people think of it as the largest canyon in the world, it isn't. It has massiveness, scenic beauty and stupendous three-dimensional exposure — but it isn't the world's largest canyon.
Nope, the Capertee Valley in Australia is wider than the American Grand Canyon. But it's not as spectacular, and, because of Australia's antiquity, not as deep. It's about 135 kilometres north-west of Sydney, between Lithgow and Mudgee.
But the deepest canyon on Earth? That's the Grand Canyon of Yarlung, in the south-eastern corner of Tibet.
For a comparison, the Grand Canyon is 446 kilometres long and plunges over 1.6 kilometres below its rim down to the riverbed. At its widest, it's about 19 kilometres across.
Now for the question of how to compare one scenic eroded monument with another — do we compare length or depth? The Great Canyon of Yarlung wins on both counts. It's a little bit longer — 496 kilometres long. But it's an astonishing 3.7 kilometres deeper. Yep, it's 5.3 kilometres from the rim to the riverbed.
This canyon was carved out by one of the mightiest rivers in Asia — the Brahmaputra. Along its 2,900-kilometre length, this river has many names — the Yarlung Tsangpo/Zangbo (in Tibet), the Siang (in India's Arunãchal Pradesh) and so on. It eventually meets up with the Ganges, and together they form the largest river delta in the world in the Bay of Bengal in Bangladesh. In the rainy season, it carries about 14,200 cubic metres of water each second.
The Brahmaputra starts in far west Tibet, rising in the Kailash mountain range. It then flows mostly east for about 1,100 kilometres, staying a little north of, and parallel to, the Himalayan mountain range. In the far eastern end of Tibet, it then performs a bizarre 260-degree turn while cutting through the highest mountain chain on Earth, the Himalayas. Here, at The Great Bend of the Yarlung Tsampo, it bends first to the north, then to the east, then the south. While heading north, it cuts between two mountain peaks just 20 kilometres apart — Gyala Peri and Namcha Barwa (each over seven kilometres above sea level).
This is the location of the world's deepest canyon. Like the river that runs through it, the canyon goes under many names — The Great Canyon of Yarlung, the Namcha Barwa Gorge, the Yarlung Tsangpo Canyon, the Tsangpo Gorge, etc. There is a very steep drop of over five kilometres from the top of Gyala Peri to the river. The walls of the canyon are three times steeper than the Grand Canyon, while the tilt of the river is eight times greater than the Colorado River.
In 1994, the American Geography Committee, in light of expeditions to this enormous gorge, named it as "The Grandest Canyon On Earth", snatching the honour away from the Grand Canyon in Arizona.
But recently, there have been strange happenings in Arizona.
Tom Vail and his wife, Paula, operate Canyon Ministries, which runs "Christ-centered motorised white-water rafting trips" on the Colorado River in the Grand Canyon. He has written a book, The Grand Canyon, A Different View. It argues from a biblical point of view. It fancifully claims that the Grand Canyon is only a few thousand years old, and that it was formed in a few days by massive erosion from the release of huge lakes of trapped water left over after the great flood of Noah.
His book has an anti-evolutionary point of view. But it is sold in shops in the national park, that in turn, fund research into the evolutionary origins of the Grand Canyon. I guess that God moves in mysterious ways…
Published 22 May 2012
© 2015 Karl S. Kruszelnicki Pty Ltd