Dripping with stalactites and glistening crystals made of salt, the Malham cave at the southern tip of Israel’s Dead Sea is the world’s longest salt cave system, researchers have claimed, following a survey of its twisting and dramatic tunnels.
The cavern, which extends over six miles (10km) underground, is believed to be even more extensive than Iran’s Namakdan cave, which was previously thought to be the longest salt cave.
The Malham cave comprises of a hundred different chambers, the longest of which stretches for 5,685 metres.
The claim was made on Thursday after a fresh exploration of the cave system led by the Hebrew University (HU) of Jerusalem as well as Israeli, Bulgarian and other international volunteers who have been mapping the site for decades.
The Malham cave’s main opening is located close to a salt pillar popular with tourists named “Lot’s wife”, after the biblical character who was petrified for looking back at the destruction of the cities of Sodom and Gomorrah.
Salt caves are rare geological features, and only a handful are larger than half a mile in length. They tend to exist in highly arid regions, like the area around the Dead Sea, which is located at the lowest point on Earth and is too salty to support animal life.
The cave system was formed by water that dissolved the salt and other minerals deposited beneath the Earth’s surface and created channels. The process would have been at its most intense during the rare periods of heavy rainfall in the Mount Sodom area, which typically sees around just 50mm of rainfall a year.
The solubility of salt means mineral erosion takes place much faster than in limestone caves, allowing caves and tunnels to be cut out at a geologically rapid rate.
Striking images from inside the cave system show delicate curtains of fragile white salt stalactites.
“Mapping Malham cave took hard work,” Efraim Cohen, a member of HU’s research team, told the Jerusalem Post, describing long days underground in the system, which was first identified almost 30 years ago. “We worked 10-hour days underground, crawling through icy salt channels, narrowly avoiding salt stalactites and jaw-dropping salt crystals. Down there it felt like another planet.”
Boaz Langford, a researcher at the university’s Caves Research Centre, and Antoniya Vlaykova, a Bulgarian cave explorer from the European Speleological Federation, headed the expedition.
“What’s unique about this cave, as opposed to other salt caves in the world, is that it’s the longest in the world,” Langford said, resting in a chamber of the cave dubbed the “Wedding Hall” for its salt stalactites.
“The salt layers are squeezed out from the sub-surface, where they are deposited a few kilometres underground, and while being squeezed out they form a mountain, which is rising still today, at a rate of about one centimetre per year,” said Amos Frumkin, a HU geologist who has studied the cave for decades.
Yoav Negev, founder of the Israel Cave Explorers Club, said that for over two years his group and a total of 80 volunteers from nine countries spent around 1,500 workdays measuring and mapping the cavern’s recesses. “It’s above and beyond what we expected,” he said.
Radiocarbon dating of wood fragments found inside the cave have helped date its formation to around 7,000 years ago, making it extremely young by speleological standards.
“The reason why it’s so young is because it’s made of salt,” Frumkin explained. “Limestone caves are much slower to form. They are usually much older. But this one is developing very fast so it’s one of the youngest caves in the world.”
Although the scientists have completed their study, there is still more of the cave that is undiscovered, he said.
“There are some more parts, especially upper levels, which have not been surveyed yet because they are difficult to reach,” Frumkin said.
