How were China's peculiar table-shaped mountains formed?

In our impression, what should mountains look like? Or should they be round, like steamed buns? The mountains in the low mountainous areas in eastern my country are roughly like this. Their formation is mostly related to water erosion. The flowing water is very gentle, and the mountains eroded by it are also round and soft.

Or are the mountains sharp and sharp, like cones or swords? The mountains in our western high-altitude areas are roughly like this. Their formation is related to glaciers. The glaciers are very strong and hard, and the mountains they carve out are also rough and angular. We also call them Houjiao Peaks.

▲Photographing Mount Gongga from Jiaoding Mountain. Mount Gongga is a mountain formed by glaciers, with rough lines and pyramid-shaped peaks. Photographed by Li Zhongdong

There is another type of mountain, which has many steep cliffs and their formation is mostly related to geological structure. Under the uplift and compression of the earth's crust, the rocks break and bend, forming monocline mountains, block mountains and fold mountains.

Among them is a type of mountain formed by block structure. The mountain body is high and the top is as flat as a desk. There are cliffs on all sides overlooking the sky. The outline of the sky outlined under the blue sky is straight and regular. This is a table mountain.

Table-shaped mountains are not uncommon in the world, and the most famous one is Mount Roraima, which is located at the junction of Brazil, Venezuela and Guyana in northern South America. Mount Roraima rises from the plains and floats in the clouds, with a magnificent momentum. In 1912, Arthur Conan Doyle, the author of Sherlock Holmes, used this mountain as the background to create the science fiction novel "The Lost World", which made this mountain famous.

In fact, there are also three such table-shaped mountains on the southwestern edge of the Sichuan Basin in western my country. They are arranged in a triangular shape, like castles in the sky, suspended in the clouds. Mr. Shan Zhiqiang, editor-in-chief of National Geographic China, calls them "China's table-shaped mountains."

▲Mount Roraima in northern South America is the largest table mountain in the world. Photo/Internet

01

Table Mountains in China

In May 2015, I accompanied Mr. Shan Zhiqiang from National Geographic China to the junction of Leshan, Meishan and Ya'an on the southwestern edge of the Sichuan Basin.

The purpose of Mr. Shan's trip was to explore China's table-shaped mountains. He visited Mount Emei and Mount Wawu. His itinerary originally included Mount Dawa. Unfortunately, just as we were preparing to set off, Mr. Shan had to return to Beijing due to an urgent matter, and we never made the trip to Mount Dawa.

In the article "Visiting China's Table Mountains" which was later published in the 6th issue of "National Geographic China" in 2015, he wrote: "Winding and undulating is people's usual impression of mountains. In addition, there is another type of mountain that is not common. They have steep walls and flat tops like tables, which are vividly called table mountains. Among the mountains on the southwestern edge of the Sichuan Basin, Wawu Mountain and Dawa Mountain are typical representatives of my country's table mountains. The two mountains are less than 40 kilometers apart in a straight line, and their shapes are quite similar: a solitary peak rises from the ground, the top of the mountain is flat like a table, and it is surrounded by steep cliffs. If the alternating peaks and valleys reflect the beauty of the curves of the mountain, then the table mountain offers the beauty of the straight lines of the mountain. The knife-like straight skyline it outlines is the best interpretation of this beauty."

▲In 2015, when I was investigating Wawu Mountain with editor-in-chief Shan Zhiqiang, we finally waited for Wawu Mountain to emerge by the Yanu Lake. Photo by Li Zhongdong

In fact, Mr. Shan Zhiqiang was not the first to discover this kind of beauty.

More than a decade ago, when investigating Dawa Mountain, Mr. Fan Xiao, a geological and geomorphological expert, discovered that Dawa Mountain was not isolated, but formed a magical triangle with Wawu Mountain in the northwest and Emei Mountain in the northeast. He called these three mountains the fault-block mountain group on the southwest edge of the Sichuan Basin, that is, the table-shaped mountains formed by the fault blocks.

The three mountains called table-shaped mountains are Mount Emei in the east, Mount Wawu in the north, and Mount Dawa in the west. They are arranged in a triangular shape, about 30 kilometers apart. In terms of topography, they have three most notable common features, that is, the top of the mountain is flat, the mountain body is abrupt, and there are nearly 1,000-meter cliffs or steep slopes around.

▲Dawa Mountain beside the Dadu River. Photo by Wang Zhi

Among the three mountains, Wawu Mountain has the largest peak area, reaching 11 square kilometers. The second is Emei Mountain, with a continuous gentle slope platform area of ​​about 4.8 square kilometers in the Jinding and Wanfoding areas. The smallest is Dawa Mountain, with a peak platform area of ​​1.6 square kilometers.

In terms of height, Dawa Mountain is the highest at 3,236 meters above sea level; Emei Mountain is the second highest at 3,099 meters above sea level; and Wawu Mountain is the lowest at 2,830 meters above sea level.

In addition, they also have something in common in terms of the material composition of the mountains. Their tops are both made of basalt formed by volcanic eruptions about 250 million years ago and Permian Yangxin Formation limestone formed by ocean sedimentation. These two hard rocks serve as the "top" of the mountains, which is equivalent to putting on a helmet for the mountains, preventing them from weathering and collapsing in the wind and rain erosion.

▲The three mountains are equidistant and arranged in a triangular shape.

02

Mount Emei, East Peak

Mount Emei is the eastern peak of the Chinese-character table-shaped mountain group. It rises from the Emei-Leshan Plain and forms the southwestern barrier of the Sichuan Basin. Among the three table-shaped mountains, Mount Emei is neither the highest nor the largest in area, nor even the most typical, but it is the most famous.

Compared with Dawa Mountain and Wawu Mountain, the cliff of Mount Emei is the largest only on the east slope, with a vertical height of about 800 meters, which is extremely spectacular. Moreover, the rock layer that constitutes the top of Mount Emei has an angle tilted to the west, so the top of Mount Emei is not nearly horizontal like Dawa Mountain and Wawu Mountain, but presents a gentle slope. In terms of scale, the continuous gentle slope platform of the top of the mountain in the area of ​​Jinding and Wanfoding is about 4.8 kilometers.

▲Mount Emei. Photo by Wang Zhi

Mount Emei is located on the western edge of the Yangtze Plate. The Mount Emei fault running in the northeast and the Fengdumiao fault running in the northwest are used as boundaries to divide the Mount Emei area into three first-level fault blocks. The west side is the Mount Emei fault block, the south-west side is the Er'e Mountain fault block, and the east side is the Emei Plain fault block. The Mount Emei scenic area is located in the cone-shaped Da'e Mountain fault block surrounded by the Mount Emei fault, the Xinkai Temple fault, the Magou fault, the Da'e Temple fault, the Wannianchang fault, and the Maziba fault. The upper part of the mountain is basalt formed by volcanic eruptions, and the lower part is limestone formed by marine environment deposition. The two different rocks together constitute the most precipitous cliffs and table-shaped flat-topped mountains.

▲The top platform of Mount Emei. Photo by Shi Yaochen syc (Photo by Tuchong Creative)

The Tang Dynasty poet Li Bai once praised that "Emei Mountain is higher than the western sky" and "There are many fairy mountains in Shu, but Emei Mountain is unmatched". The Southern Song Dynasty poet Fan Chengda wrote that "The beauty of the three Emei Mountains is the best in the world". Emei Mountain is known as one of the four famous mountains of Chinese Buddhism, along with Wutai Mountain in Shanxi, Putuo Mountain in Zhejiang, and Jiuhua Mountain in Anhui. It is the world-famous place of practice for Samantabhadra Bodhisattva. The main peak, Wanfoding, is 3,099 meters high, nearly 2,500 meters higher than the Chengdu Plain.

Mount Emei is not only one of the four famous Buddhist mountains in China, but also well-known for its rich geological phenomena. The Sinian-Cambrian stratigraphic section and the Longmendong Triassic sedimentary section are very well-known in the geological community and have become a base for Chinese and foreign geoscience research and domestic geology and geography teaching and practice.

The "Emeishan Basalt" named after Mount Emei was formed by volcanic eruptions 250 million years ago and is comparable to the Deccan Plateau basalt in India. It was named by Mr. Zhao Yazeng in 1929. The young geologist was later killed by bandits during a field survey in Zhaotong, Yunnan. He was only 29 years old when he died.

▲The Emeishan basalt named by Zhao Yazeng. Photo by Li Zhongdong

03

Beifeng Wawu Mountain

Wawu Mountain is the northern peak of the three-shaped table-shaped mountains. It was called Jushan, Shushan, and Laojunshan in ancient times. As early as the Tang and Song Dynasties, it was called "the two wonders in Shu" together with Mount Emei. It is said to be the place where Taishang Laojun ascended to heaven, the birthplace of Taoism, and the last place where the Qingqiang people stayed. Wawu Mountain is surrounded by cliffs, forming a roof-like mountaintop that is slightly inclined to the east and west. No matter from which angle, it looks like a tiled house from a distance, so it is named "Wawu Mountain". Literati of all dynasties have sung praises to Wawu Mountain. Su Shi's "Wawu is cold and piled with snow after spring, and Emei is green and sweeps the rainy day" and He Shaoji's "The scenery of Bashu, Emei accounts for three out of ten, and Wawu accounts for six or seven" are the most widely circulated and quoted.

▲Wawu Mountain. Photo by (TuChong Creative)

The top of Wawu Mountain is flat and wide, 3,375 meters long from north to south and 3,475 meters wide from east to west, with an average altitude of 2,830 meters. The platform area is 11 square kilometers. It is the second largest mountaintop platform in the world after Mount Roraima, and also the largest platform among the three table-shaped mountains.

There are wetlands, lakes, springs, streams, lush forests and wild animals on the platform. When it is sunny in the morning and cloudy in the evening, standing on the top of the mountain, Xianger Rock, Duguang Terrace or Pizhi Buddha Cliff, you will see clouds and mist, Buddha light moving, holy lights flickering, and it is magical and ethereal.

The upper part of the platform is Emeishan basalt, forming a hard "top cover". Below the basalt "top cover" is a thick carbonate rock, forming a cliff hanging in the air on all sides. The vertical height of the cliff is 700 to 800 meters, and its scale and grandeur are extremely rare.

▲Wawu Mountain. Photographed by Yundanfengqing16 (Tuchong Creative)

The rock formations that make up the cliffs are gentle, like thousands of volumes of heavenly books stacked one on top of another. On the cliffs, waterfalls hang high, and have been called "hanging banner waterfalls" since ancient times. Among them, the three major waterfalls of Lanxi, Yuanxi and Yangxi are the most spectacular. The Lanxi waterfall has a drop of 1,040 meters and an average flow of 2.4 cubic meters per second, like the Milky Way falling.

Wilson, a famous British botanist, climbed Wawu Mountain in 1908. In his article "Travels in Wawu Mountain", he wrote: "It is thick, square and heavy, and its entire outline is like a huge ark floating above the clouds."

▲A high mountain waterfall falling from the platform of Wawu Mountain. Photo by Yang Jian

04

Xifeng Dawashan

Dawa Mountain is the western peak of the three table-shaped mountains. Its geological structure is the same as that of Mount Emei and Mount Wawu, both of which are typical fault-block mountains, but it is more abrupt and majestic than Mount Emei and Mount Wawu. With an altitude of 3,236 meters, it is the highest among the three mountains. It is surrounded by cliffs, forming a table-shaped square mountain with a flat top and surrounding areas. The top area is about 1.6 square kilometers, which is the smallest platform area among the three mountains.

Looking down from the air, the top of Dawa Mountain is an isosceles triangle, with the northeast, southeast and west sides about 1,750 meters, 2,000 meters and 3,000 meters long respectively. Below the top is a cliff, with three vertical steep cliffs, like three tiles, hence the name "Dawa Mountain".

▲Dawa Mountain. Photographed by Afeng001 (Photo by Tuchong Creative)

One day in June 1903, British botanist Wilson saw this isolated mountain surrounded by cliffs for the first time from the top of Mount Emei. He later wrote in his article: "When Mount Wa first appeared in front of me, about 20 miles away, I could hardly believe that it was Mount Wa - it looked like such a huge cliff, its grandeur dwarfed its height."

"Looking from the top of Mount Emei, Dawa Mountain looks like a huge Noah's Ark, with the side of the ship towering in the sea of ​​clouds." On July 1, 1903, Wilson and his dog climbed Dawa Mountain for the first time. However, the weather was not good. Wilson's trip to Dawa Mountain was always in rain and fog. When he was going down the mountain, he was soaked by the rain and became a "drowned chicken", and the dog also became a "drowned dog".

▲British botanist Wilson.

Before Wilson came, there was already an American explorer who had been here, EC Beber. Information about Beber is so scarce that we almost doubt his existence. We can only learn about him through Wilson's book "A Naturalist in Western China".

According to Wilson's record, Beber climbed the Great Wall Mountain on June 5, 1878. Beber called the Great Wall Mountain "the most magical natural park in the world" and his report was full of praise for the Great Wall Mountain. More than 20 years later, when Wilson also faced the Great Wall Mountain, he could not find better words than Beber to describe it. Wilson exclaimed, "His description of the Great Wall Mountain is so accurate and beautiful that I can't do better and can only quote his report."

▲Dawa Mountain. Photo by Wang Zhi

05

Why do table mountains form?

How did such a peculiar mountain form? The formation of the table-shaped mountain group is mainly due to three aspects. First, the material composition is special; second, the geological structure, mainly uplift and faulting; third, the continuous downcutting of the Dadu River and the Qingyi River. The material composition of this area is mainly composed of carbonate rocks and basalts with strong weathering resistance and mudstones and sandstones with weak weathering resistance. They are stacked horizontally, like a stack of flat books, and horizontal rock layers are usually more likely to form abrupt mountains and steep cliffs. Affected by differential weathering, the hard carbonate rocks and basalts form steep cliffs, while the weak sandstone and mudstone form gentle slope platforms, showing the characteristics of alternating steep cliffs and gentle slope platforms.

▲Dawa Mountain. Photo by Wang Zhi

From a distance, the table-shaped mountains have two largest cliffs. The lower cliff is composed of limestone and dolomite formed about 600 million years ago. It mainly forms the lowest part of the table-shaped mountain, showing a series of deep canyons. The upper cliff is composed of limestone and Emeishan basalt about 250 million years ago. The most spectacular part we see, the mountain suspended in the clouds, is this part.

It should be pointed out that the extremely thick basalt on the top is the key to the formation of the mountaintop platform of the table mountain. It is like putting a safety helmet on the mountain, protecting the steep cliff below from erosion by wind and rain, thus allowing the shape of the table mountain to be maintained.

In terms of geological structure, with the uplift of the Qinghai-Tibet Plateau, this area is bounded by two groups of faults in the northwest and northeast, forming fault blocks of different orders. Dawa Mountain, Emei Mountain, and Wawu Mountain are actually composed of these secondary fault blocks. Moreover, the cross-sections of these two groups of faults are nearly vertical. For example, the spectacular Sheshen Cliff of Emei Mountain is formed along the uplift of this fault and at its front edge. It can be said that the fault confinement and block structure are of great significance to the formation of the three isolated suspended table mountains.

▲Schematic diagram of the formation of fault-block mountains. Drawing/Zhou Ruoxuan

The formation of the table-shaped mountain is due to the unique material composition, the confinement of two sets of faults and the resulting block structure, and finally the continuous cutting of water over the years. The rapid uplift of the Qinghai-Tibet Plateau has led to a large difference in topography in the entire region, which has created conditions for the rapid cutting of the Dadu River and the Qingyi River.

Like a scalpel, they accurately and fiercely cut along the fractures and fissures, forming dense canyon groups such as the Dadu River Grand Canyon. The erosion of flowing water also carries away the soft rocks, making the mountains shorter and making the table-shaped mountains topped with hard basalt appear taller.

▲Three table-shaped mountains. Photo by Wang Zhi

06

Will there be new Tabular Mountains?

The southwestern edge of the Sichuan Basin has similar rock composition, geological structure, and climate. Apart from these three table-shaped mountains, are there other similar landforms? In particular, the volcanic eruption that occurred 250 million years ago covered an area of ​​500,000 square kilometers of basalt, spanning Sichuan, Yunnan, and Guizhou. Can we find table-shaped mountains with basalt as the cap in these places?

In fact, in addition to the above-mentioned table-shaped mountain, there is also a prismatic plot of land with an area of ​​about 26 square kilometers in the Fuxing Village area of ​​Hongya County between Dawa Mountain and Wawu Mountain. The outline is very clear, with the same rock strata and components, the same flat top and steep cliffs around it, but the average altitude is only about 2,300 meters, and the highest cliff is less than 400 meters.

There are also such fault-block mountains and basalt "caps" in Maoke Mountain (3,225 meters) connected to Dawa Mountain, Quequeling (3,000 meters) across the Dadu River, Meilingding (3,263 meters) at the source of the Liziyi Da debris flow ditch on the Chengkun Railway, Ma'anshan (4,288 meters) adjacent to the "Bermuda of China - Heizhugou" in Ganluo and Ebian County, and Datuanyan (3,077 meters) and Dafengding (4,042 meters) in Mabian County. Then, during the investigation, it was found that these mountains were either tilted or squeezed and deformed, and therefore did not have the conditions to form table-shaped mountains, but we still look forward to more discoveries in the future, and China's table-shaped mountains will continue to be new.

▲Maoke Mountain next to Dawa Mountain has a similar geological structure to Dawa Mountain, but does not have a table-shaped top. Photo by He Wei

-END-

References:

1. Li Zhongdong, Zhou Jiangling, Zou Rong, et al., "Great River Gorges", China Tourism Press, April 2019;

2. Shan Zhiqiang, Exploring China’s Table Mountains, Chinese National Geographic, No. 6, 2017;

3. Fan Xiao, Tectonic block mountains and Washan landforms on the southwestern margin of the Sichuan Basin, Proceedings of the 23rd Annual Meeting of the Tourism Geology and Geopark Research Branch of the Geological Society of China and the Seminar on the Construction and Tourism Development Strategy of the Erlian Dinosaur Geopark.

By Li Zhongdong

Image | Wang Zhi, Yang Jian, Li Zhongdong, TuChong Creative, etc.

Source: "Xia Ke Geography" public account