Travelling through the Three Gorges and looking at the torrential
waters, cloud-piercing peaks and sheer precipices, people often wonder how the Three
Gorges came into existence.
Before mankind had any knowledge of science, people relied on legends to explain the
natural phenomena. It was said that the Three Gorges were blazed by Da Yu, the legendary
king, or by the fairy Yao Ji. These, however, are only fairy tales.
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Dragon
Back Rock in Golden Helmet and Silver Amour Gorge
Geologically, the Three Gorges were formed by powerful organic movement, which turned
sea into land and land into sea and created new rivers.
As early as 200 million years ago, during the Triassic period, China was
topographically higher in the east and lower in the west. The area to the west of today’s
Yangtze River valley was an extensive sea linked with the ancient Mediterranean Sea. The
vast sea extended from the Three Gorges area to Tibet, Qinghai, Yunnan, Guizhou and
Sichuan. Today's Zigui was on the sea shore.
Coal-containing sediments of alternating land-sea faces have been discovered in the area.
At the end of the Triassic period nearly 200 million years ago, a powerful organic
movement ( the Indochina movement) took place on earth, The Three Gorges area of today was
of course also affected. The movement did not form any tall mountains in this area. But as
a result of the rise of the earth’s crust, the ancient Mediterranean Sea fell back a long
distance to the west and the Three Gorges area became dry land. At the same time, the
Qinling Mountains in China began to rise.
As a result, the land rose in the east and fell in the west. Also in this period the
now famous Huangling anticline began to take shape and emerged above the sea level.
Several large bodies of water, including the lakes Zigui, Bashu, Xichang and Dianchi,
remained in its west. Three lakes, with the exception of Zigui, were linked by a water
system flowing the east to the west through the Nanjian Straits into the Mediterranean
Sea. This water system was the embryo of the western section of the Yangtze River. To the
east of the Huangling anticline were the lakes Dangyang, Exiang, Poyang and many others
which were also linked by a large river, the embryo of the eastern section of the Yangtze.
Nine
Dragons Sailing on the River
About 70 million years ago, another mountain forming movement, the Yanshan movement,
took place. The Sichuan Basin and the Three Gorges area rose and Lake Zigui disappeared,
and the Dongting and Yunmeng basins began to fall.
Large quantities of pebbles and fossils which remained at lake bottom of the past
geological periods can be found on top of the mountains as high as 1,000 meters above sea
level in the Three Gorges area.
In the immensely powerful mountain-making movements, the think crust of rock was
crushed and bent like waves in the sea. These wave-like rock strata are geologically known
as "folds". The top of a wave is called "anticline" and the wave
bottom, "syncline". The three anticlines of Qiyao, Wushan and Huangling in the
Three Gorges area were formed in the Yanshan movement. After the rise of the three
anticlines, the rivers on either side flow in different directions. The Yangtze River
water system had not yet come into existence.
An isle in the river, with a Daoist
Temple
During the organic Himalayan movement of 30-40 million years ago, the earth surface of
the Yangtze River valley rose intermittently, most drastically in the upper reaches,
giving rise to many tall mountains, high plateau and deep valleys. The middle and lower
reaches rose less drastically and some places even continued to fall, forming many hilly
areas, plains, lowlands and lakes.
As a result, the topography became higher in the west and lower in the east. Even
today, the earth crust in the Three Gorges area is still slowly on the rise. It has been
measured that the Huangling anticline rises 2-4 millimeters every year. After the rise of
the anticline of the Three Gorges area, the rivers on either side of them, i.e., the west
"Yangtze" and east "Yangtze" came gradually closer as a result of the
downward flow of one and the erosion on the upper reaches of the other in tens of
thousands of years. Because the terrain was higher in the west and lower in the east and
the east river flew down a steeper gradient, it was more powerful in its erosion than the
west river. The three anticlines of the Three Gorges were eventually pierced and the two
rivers became one and flows now to the east.
After the Three Gorges came into existence, the turbulent river began to wash the river
bed and the banks continually day and night. The river bed deepened and valley widened.
Stubbornly and irresistibly the great Yangtze thus broke through the valley and the
mountains and flows forever onwards.
Silver
armor
