Recently, after on-site inspections by experts, it was confirmed that the Sansha municipal government officially named the Ocean Blue Hole in the Yongle Atoll of the Paracel Islands "Sansha Yongle Blue Hole" (Sansha Yongle Blue Hole), which was confirmed to be the world's largest The deepest known ocean blue hole is located in the reef of Sansha City Yongle Atoll of Xisha Islands Jinqing Island and Shiyu, with a depth of 300 meters. 89 meters, the address coordinates are 16°31′30″ north latitude and 111°46′05″ east longitude.
Data map provided by Xinhua News Agency
Ocean blue holes are a rare natural geographical phenomenon on the earth. Viewed from the sea surface, the blue holes show a different dark blue color from the surrounding waters, and form a huge deep hole on the seabed. They are praised by scientists as the "Earth" The last legacy that preserves the secrets of the universe for mankind." The previously proven depth rankings of ocean blue holes in the world are: Bahamas Long Island Deans Blue Hole (202 meters), Hadab Blue Hole in Egypt (130 meters), Belize Great Blue Hole in Honduras (123 meters), Malta Gogo The depth of Zuolan Cave (60 meters) and Xisha Yongle Blue Cave has set a new world record for ocean blue holes.
"Sansha Yongle Dragon Cave" has a long legend. Hainan fishermen claim that this is where the Dinghai Divine Needle is. Sun Wukong pulled out the Dinghai Divine Needle to make a wish-fulfilling golden hoop, leaving an unfathomable dragon cave. Some fishermen also say that the Dragon Cave is the eye of the South China Sea and contains hidden treasures. The treasure of the South China Sea.
From August 2015 to June 2016, the Xisha Track Research Institute adopted equipment such as sonar side scan equipment, electronic counting plumbs, deep sea current meters, deep sea water quality analyzers, underwater robots, and underwater photography equipment. The method of combining scientific equipment detection and artificial diving observation and measurement has successfully determined the depth and basic shape of the blue hole. The expert team, headed by Meng Wei, an academician of the Chinese Academy of Engineering, determined that the exploration results were credible.
After investigation, the Yongle Blue Cave in Xisha is basically a vertical cave. The diameter of the blue cave is 130 meters, and the diameter of the cave bottom is about 36 meters. It has not been observed that the blue cave is connected to the outer sea, and there is no obvious flow of water in the cave. Through visual inspection, more than 20 kinds of fish and other marine life similar to those in the surrounding sea were found in the upper layer of the cave.
After review by Sansha City, Hainan Province and an expert group, the Sansha Coral Reef Conservation Research Institute announced that the proven depth of the "Yongle Dragon Cave" in Xisha is 300.89 meters, surpassing the 202-meter ocean blue hole on Long Island in the Bahamas and becoming the world's deepest known ocean blue hole.
The Sansha Municipal Government pointed out that the "Sansha Yongle Dragon Cave" has extremely high scientific research value and historical and cultural value, and is a true testimony of the Chinese government and people's long-term persistence in ecological and environmental protection.
Extended reading:
Is there a "Dragon Cave" in China's Xisha Islands? Known as the "Eye of the South China Sea", what exactly are these ocean blue holes?
Above the vast sea, a dark blue round water will suddenly appear. Viewed from a high altitude, it seems to be the pupil of the sea. Viewed from the depths of the earth, Come, deep, mysterious and strange, this peculiar natural landscape is called the blue hole. Since ancient times, people have made many speculations about the blue hole, which have cast a mysterious veil on the blue hole. So, what exactly is a blue hole and what’s inside it?
Author: Bai Hongxin Chen Xiaomei
The legend of the Blue Cave has existed since ancient times
As far back as the ancient Roman era, some people went to explore the Blue Cave, and it was said that "the Blue Cave is a base for contemporary witches to cultivate their health and practice magic power." This makes the Blue Cave His true appearance has never been known and is always shrouded in mystery.
In China's Xisha Islands, there is a "Dragon Cave" that is passed down by fishermen orally. Because it is unfathomable, fishermen are in awe of it and it also has a long legend. Some say that there is a large sea monster in it and should be avoided; others say that it is the "Eye of the South China Sea" because it contains the "Dinghai Divine Pearl", a treasure that holds the sea; others say that this is the location of the "Dinghai Divine Needle". Sun Wukong made a big fuss in the Dragon Palace and pulled out the Dinghai Divine Needle to use as the Ruyi Golden Cudgel, leaving this unfathomable hole.
Of course, these are just legends. The ocean blue hole is a rare marine geographical phenomenon on the earth. Compared with the surrounding waters, the water in the blue hole shows a deep blue tone.
How are blue holes formed?
So how are these mysterious blue holes formed? According to Professor Yang Zuosheng of Ocean University of China, there are currently two types of causes of ocean blue holes, namely the causes of limestone cavesand the causes of coral reef growth structures.
The so-called limestone cave means that due to the lowering of sea level during the glacial period, the limestone was eroded and developed into a large cavity (similar to a karst cave) in the lower part. When the denudation cavity became larger and larger, it caused the top to collapse and form a large hole with steep edges. , called sinkhole . After the ice age ended, the sea level rose, and seawater refilled the sinkhole, which became the "blue hole" that everyone sees.
This type of blue hole contains a large number of stalagmites, stalactites, etc., and the cracks are developed, often forming several channels connected to the outside sea water. There is a certain exchange between the water body in the cave and the outside sea water. There may also be a limestone wall or cave roof at the bottom of the cave. A large amount of products fell when erosion and collapse occurred. The famous Belize Great Blue Hole belongs to this type. The
coral reef growth structural model was proposed in the late 1990s, the most typical of which is the Hautman-Abrolhos Coral Reef Blue Hole on the southwestern outer shelf of Australia.
Since the Holocene 10,000 years ago, the coral reefs in this sea area have grown rapidly. Many rapidly growing smaller reefs have formed spine-like protrusions and gathered together, eventually forming an approximately circular hole. The internal water environment of the cave has a significant impact on the growth of corals, while the external water environment is conducive to the growth of corals, gradually developing into a blue hole with larger water depth. There are no stalagmites, stalactites and other products observed in this type of blue hole. There is no channel for exchange with the outside seawater, and there is coral sand at the bottom.
What's in the Blue Hole?
The mysterious blue hole has become an adventure destination for diving enthusiasts. World-famous divers have tried the fun of diving in the blue hole. These blue holes have also become very attractive tourist attractions.
Because blue holes are usually hundreds of meters deep and severely lacking in oxygen, they cannot support the survival of most marine life. There is no interference from modern biological activities here, which is conducive for scientists to study ancient fossil remains and other sediments here.
For example, scholars from Rice University and Louisiana State University studied sediment samples extracted from BelizeThe Great Blue Hole and found that the age of the samples ranged from 1,000 to 800 years ago, which is consistent with The decline of the Mayan civilization occurred during the same period. Through the analysis of elements (titanium) in the samples, it was found that the number of tropical cyclones during this period was less than before, and droughts were longer than before.
The Yucatan Peninsula where Belize is located is an area with relatively scarce water resources. At that time, the Mayans mostly relied on rainwater stored in limestone pits to survive drought periods. However, long-lasting droughts may have exhausted the stored water. drinking water. After the water crisis, famine, turmoil and war followed, which led to the decline of the Mayan civilization. Therefore, blue holes are called by scientists "the last legacy that preserves the secrets of the universe."
Knowledge is powerContributed by
(Original title: What is the mysterious "Blue Hole")
Source: Comprehensive China Youth Network Beijing Evening News
Process Editor: tf019
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