An international expedition led by Hebrew University cave researchers have, after 38 years of exploration, mapped Malham Cave – a salt cave in the Dead Sea region – as the longest in the world.
Since Lot’s Wife looked back at the destruction of the evil city of Sodom (today, Sdom in modern Israel), there hasn’t been such big news about salt.
It thus takes the title from what was for the last 13 years the longest salt cave – Iran’s Cave of the Three Nudes (3N) on Qeshm Island.
Now, the Israeli-led expedition, which included cavers from the Hebrew University’s Jerusalem Cave Research Center (CRC), Israel Cave Explorers Club, and Bulgaria’s Sofia Speleo Club, along with 80 cavers from nine countries, has successfully mapped the Malham salt cave in the Dead Sea’s Mount Sodom.
Malham is the world’s first salt cave to reach a double-digit kilometer length. By comparison, Iran’s Qeshm Island salt cave, now the world’s second longest, measures only 6,580 meters in length. The cave is notable also because it contains a stunning array of salt stalactites and salt crystals within its chambers. These salt “icicles” hang from the cave’s ceiling and grow longer and fatter as each drop of water rolls down before evaporating into the salty air.
The cave was initially discovered by the CRC, which is the only cave research center in Israel, back in the 1980’s. Later, dozens of CRC expeditions surveyed the area and found more than 100 different salt caves inside, the longest of which measured 5,685 meters. Subsequent carbon-14 tests dated the cave as about 7,000 years old, and successive rainstorms created new passages for the cavers to explore.
When the international expeditions returned to Malham in 2018 and 2019, their surveys discovered the cave’s record-breaking, double-digit kilometer length. “Thirty years ago, when we surveyed Malham, we used tape measures and compasses. Now we have laser technology that beams measurements right to our iPhones,” Frumkin recalled.
Currently, the survey team is processing final data from the new Malham Cave surveys to create an electronic map of the cave and to publish its findings.
The international cave expeditions that worked together to map Malham Cave include Israel’s Cave Explorers Club, HU’s Cave Research Center, and Bulgaria’s Sofia Caving Club & Speleo School. The survey team included cavers from Israel, Bulgaria, France, United Kingdom, Croatia, Romania, Germany and the Czech Republic.
Boaz Langford, a member of of the CRC and head of the 2019 Malham Cave Mapping Expedition explained: “Israel’s salt caves are a global phenomenon. My colleagues around the world are always amazed at what we find here. Returning to survey Malham Cave allowed us to reveal its full dimensions and rank Israel as first among the world’s longest salt caves.
“This entire project began with a call to Antoniya Vlaykova at Bulgaria’s Sofia Caving Club and Speleo School. From the very beginning they showed real interest in collaborating with us and in taking on a central role in the project,” said Yoav Negev, chairman of the Israel Cave Explorers Club and project leader of the Malham Cave Mapping Expedition: “Soon we had a 50-member delegation – half international, half Israeli. The Malham Cave is a one of kind expedition that demonstrated the power of international caving delegations coming together to achieve something remarkable. The fact that we came away with a new world record is icing on the cake.”
Efraim Cohen, another CRC member, added: “Mapping the cave was hard work. We worked 10-hour days underground, crawling through icy salt channels, narrowly avoiding salt stalactites and draw-dropping salt crystals. Down there it felt like another planet. Our next and final step is to map the tightest spots and the most difficult ones to reach. When we’re all done, it’s likely we’ll add a few hundred meters to Malham’s impressive 10-kilometer length.”
Geologically speaking, salt caves are living things. They form mostly in desert regions with salt outcrops, such as Chile’s Atacama Desert, Iran’s Qeshm Island and Israel’s Dead Sea. It is water that helps them form; even arid climates like those have an occasional rainstorm. When it does rain, water rushes down cracks in the surface, dissolving salt and creating semi-horizontal channels along the way. After the rainwater drains out, these dried out “river beds” remain and salt caves are formed.
This occurred at Mount Sodom, an 11-kilometer-long mountain that sits 170 meters below sea level at the southwestern tip of the Dead Sea. Underneath a thin layer of cap rock, this mountain is made entirely of salt.
Two factors protect this mountain from dissolving away – the sturdy cap rock that covers its salt, and the dry, hot climate of the Negev Desert. Mount Sodom gets roughly 50 millimeters of rain annually, mostly in short but dramatic rain bursts. As Prof. Amos Frumkin, director of the CRC at HU’s Institute of Earth Sciences, explained, “The Malham Salt Cave is a river cave. Water from a surface stream flowed underground and dissolved the salt, creating caves – a process that is still going on when there is strong rain over Mount Sodom about once a year.” In this way, the Malham Salt Cave is “alive” and continues to grow.