On June 6, 2021, the Well of Barhout (also known as the "Well of Hell") was discovered in Yemen's al-Mahra Province. (Image credit to AFP via Getty Images).
According to news reports, cave explorers from Oman were the first to reach the bottom of Yemen's 367-foot (112-meter) deep "Well of Hell" sinkhole. Many locals believe it is a gateway to the underworld.
The Well of Barhout is a natural sinkhole that has a strangely circular entrance. It is located in the middle of desert in al-Mahra, eastern Yemen, near the border with Oman. Although amateur cave explorers have been known to have entered the sinkhole, no one has ever made it to the bottom.
A team of 10 explorers representing the Omani Caves Exploration Team used a pulley system to explore the Well of Barhout. Eight of them were lowered to the bottom, while the other two remained at the top. The event was watched by a small group of curious spectators, despite the local fear about the sinkhole. BBC shared a video of the explorers entering the cave.
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Mohammed al-Kindi, a professor of geology at the German University of Technology, Oman, said that "Passion drove" him to do so. He was also part of the OCET team. "And we felt this was something that would reveal a new wonder, and part of Yemeni History."
Although the explorers claimed to have found waterfalls, snakes and dead animals, they didn't find any genies nor a way into hell.
Myths from the local area
Although the exact age of Well of Barhout remains unknown, it is believed to be millions of years old according to AFP.
There are many local legends that explain the sinkhole. Most describe it as a prison for either genies or jinns and cause bad luck. Some believe that if people get too close to the sinkhole, it can pull them inside. Others claim that the supervolcano that is visible through the hole could destroy the Earth, but there is no scientific evidence.
People have reported that the large hole has a foul odor in the past. This led to the nickname.
The Well of Barhout, however, is a typical sinkhole.
Aerial shot of the Well of Barhout, taken June 6, 2021. Image credit: AFP via Getty Images
Sinkholes: How do they form?
Philip van Beynen of the University of South Florida, who is a sinkhole expert, said that there are many types of sinkholes. He was not part of the exploration. "The most common sinkholes are subsidence and collapse."
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When the voids below the surface of the bedrock expand to the point that the roof is no longer supported by the rock, collapse sinkholes are formed. The rock and sediment then suddenly fall into the cave. Van Beynen explained that subsidence sinkholes are formed when surface sediments gradually trickle down to small voids beneath the ground until a depression forms or sinkhole.
Both depend on a particular type of landscape known as karst. It is composed by carbonate bedrock such as limestone and dolomite and is soluble in the water. This leads to sinkholes, springs, and caves.
He said that it was difficult to determine exactly when and how sinkholes formed. It's not possible to determine the exact time of sinkhole formation unless people are present at the site to record it.
Exploring the cave
According to Omani newspaper Muscat, the floor was uneven and jagged. Some stalagmites were 30 feet (9 m) high. Cave pearls were also found on some parts of the floor. These are speleothems structures that form in caves from the gradual accumulation of minerals such as calcium carbonate from dripping water.
"They [cave pearls] are formed from dripping water as concentric layers mineral, usually around some type of a nucleus," Leslie Melim of Western Illinois University, who is a geologist who studies cave pearls. Practically, any object can act as a nuclear element, regardless of whether it is found in a cave or mine. Because the nucleus is not fixed, minerals can grow around the grain. This starts a pearl formation.
Cave pearls are rare and can only grow on cave floors that are flat enough that the nucleus isn't moving around. Melim stated that cave pearls are very rare.
According to Muscat Daily, water also emerges from cave walls at approximately 213 feet (65 meters) below the surface. Melim explained that this provides water for cave pearl formation, stalagmites, speleothems and stalagmites.
According to the explorers, they also saw snakes, frogs, and beetles in the cave system. They also observed several dead animals (mainly birds) that had fallen into the pit. Al-Kindi said that although the smell of rotting bodies could have been a factor in the stench, there was no "overwhelming bad smell" within the sinkhole.
The team collected samples that could also provide further information about the sinkhole's formation and origin. Al-Kindi said that they collected samples of water and soil, as well as some dead animals, but had yet to have their results analyzed.
In the next few weeks, a final report will be available on the exploration of Well of Barhout.
Original publication on Live Science