Mount Sodom and Lot's Wife

Mount Sodom is a diapir: a body of salt buried under kilometres of younger sediment that was squeezed sideways and then upwards through the rocks above it, because salt is both lighter than its surroundings and able to deform rather than break. The Baltimore Sun's 1991 report described the mechanism as salt pushed out sideways like toothpaste from a leaking tube, and noted that drilling crews had gone down more than 3,000 feet and found salt all the way.

The rate of rise has been measured more than once, and the answers cluster without quite agreeing. Ram Weinberger's group, combining a mechanical model with interferometric radar in 2006, reported maximum uplift rates of 8.3 millimetres a year for the northern part of the mountain and 5.5 for the southern part. Amos Frumkin, measuring at the salt pillar in work published in 2009, got 9.3 plus or minus 3.5 millimetres a year. The two halves of the ridge do not rise at the same rate, and no published figure claims better than about a millimetre of precision.

Weinberger's model fits an effective viscosity for the rock salt of 2 to 3 times ten to the eighteenth pascal seconds, and finds that the radar uplift profiles track the shape of the mountain itself, which implies the rise has been steady for roughly the last 14,000 years. The ridge a visitor sees is close to a direct readout of a process still under way.

One consequence catches people out. Height above the Dead Sea is not a fixed number here, because the lake keeps dropping away from the mountain while the mountain rises. The parks authority's own pages carry two different figures: about 150 metres above the lake on the reserve page, about 270 metres on its Mount Sodom walking route. Both are the operator's, published years apart.

• Maximum uplift 8.3 mm a year in the north and 5.5 mm in the south (2006)
• 9.3 plus or minus 3.5 mm a year measured at the salt pillar (2009)
• Uplift history stable over roughly the last 14,000 years (2006)

On 28 March 2019 the BBC reported that Israeli researchers had mapped 10 kilometres of passages and chambers inside Malham Cave, which runs through Mount Sodom, over two years of survey work. The claim was a recapture rather than a discovery: part of Malham had already been mapped in the 1980s, and Yoav Negev of the Israel Cave Explorers Club had assembled a team two years earlier to finish the job. The record it took had been held since 2006 by the Cave of the Three Nudes, a 6.85 kilometre salt cave on Qeshm Island in Iran.

The Israeli outlet Mako, reporting the day before, filled in why the number moved so far. The old Israeli figure was 5.5 kilometres. Amos Frumkin, who runs the Cave Research Center at the Hebrew University and has worked on these caves for about four decades, told Mako that thirty years ago the teams used measuring tape, a compass and a clinometer, and that the resurvey used laser rangefinders feeding straight into a tablet. Roughly fifty cavers took part, about half of them from abroad, and the project began as a collaboration with the caving club of Sofia. Frumkin dates the cave at around 7,000 years old by radiocarbon.

The speed is the point. Amos Frumkin and Derek Ford, publishing on these caves in 1995, noted that rock salt is roughly a thousand times more soluble than limestone, and that despite mean annual rainfall of about 50 millimetres the cave streams here cut down fast: an average of 8.8 millimetres a year in one passage between 1986 and 1991, and 6.2 millimetres a year over the long term from radiocarbon ages of driftwood in twelve passages. That is at least three orders of magnitude quicker than anything recorded in limestone caves. The same wood makes the caves a climate archive: Frumkin and colleagues built a Holocene sequence from fragments dated between about 7,100 and 200 years before present.

None of this is walkable on a visit. Mako's report states flatly that the cave is not set up for public visits and that any entry requires a caver who knows it, and the parks authority's warning for the mountain is that walkers must not leave the marked paths because of the risk of falling into very deep shafts. Those shafts are the tops of exactly this cave system.

• Over 10 km of passages, mapped over two years, announced March 2019
• Previous record: the Cave of the Three Nudes, Qeshm Island, Iran, 6.85 km, held since 2006
• Cave age about 7,000 years, by radiocarbon
• Not open to the public; entry requires an experienced caver

The text is one verse long. Genesis 19:26, in the Jewish Publication Society translation Sefaria prints, reads that Lot's wife looked back and she thereupon turned into a pillar of salt. Josephus went further: in the Antiquities of the Jews, book 1, chapter 11, he writes that she was changed into a pillar of salt, and adds that he has seen it and that it remains to this day. No source consulted here connects what Josephus saw with any particular pillar standing now, and salt pillars here are neither rare nor permanent.

The geological account is more specific and better dated. Amos Frumkin analysed and dated a 20 metre salt pillar on the mountain in the Geological Society of America Bulletin in 2009. Against the earlier assumption that direct rainfall had sculpted it, he found that the solution notches on the pillar and the shape of the chasm beside it point to a karst cave that collapsed, leaving the pillar isolated. Six radiocarbon dates on wood washed into the highest level of that cave show a seasonal underground stream still running there about 4,000 years ago, and Frumkin concludes the collapse was probably triggered by a catastrophic earthquake.

The pillar tourists are shown has also been treated, for at least thirty years, as something that may not last. In December 1991 the Baltimore Sun reported that rangers had noticed it leaning further out from the mountain and that measurements found it had shifted by 15 degrees. The paper put its bulk at the size of a three or four storey townhouse and noted that if it fell it would probably land on the road below. Yossi Harash, then chief geologist at the potash works, told the paper the whole area was unstable and that the mountain was moving.

The same article has the neatest summary of why any of it survives. David Meneger, then district ranger, pointed out that water dissolves a salt mountain exactly as it dissolves table salt, and that normal rainfall would have removed the place long ago.

The parks authority's recommended walk here is the Fish Trail, which it grades medium to hard, calls suitable for fit walkers, gives as 3 kilometres, and describes as linear rather than circular. It requires trail map sheet 11, South Judean Desert North, which the reserve page lists as compulsory equipment for the whole reserve rather than as a suggestion.

The directions matter because there is no signposted entrance. From Route 90, between kilometre markers 193 and 194, turn west onto the red-marked road; after about 2 kilometres carry straight on along the blue trail for a further 2.5 kilometres, and park at the sign announcing Mount Sodom. The walk ends beside kilometre marker 199 on Route 90, which means a second vehicle or a long walk back along the road.

What the route strings together, in the parks authority's own order: a climb on the blue trail to a viewpoint over the southern basin and the mountains of Moab in Jordan, then an easy descent along the ridges to Mitzpe HaKaftor, the Button Lookout, named for its domed shape and giving a view over the evaporation ponds; then a gentle drop towards the sea past salt formations thrown up as the mountain rose; then the Fish Channel and its fossil fish. The authority recommends autumn, winter and spring.

The safety instructions are unusually blunt for a page written to sell a walk. The reserve page says walkers must not deviate from the marked trails on Mount Sodom because of the danger of falling into very deep chimneys; the trail page warns of giant holes in the ground and tells parents to keep children close. Walking after dark is forbidden outright, in winter the wadis carry flash floods, and there is no drinking water anywhere on the mountain.

• Fish Trail: 3 km, linear, graded medium to hard
• Trail map sheet 11, South Judean Desert North, is compulsory
• Start: Route 90 between km markers 193 and 194, west on the red road
• Finish: beside km marker 199 on Route 90

Mount Sodom has no visitor centre, no ticket office, no toilets and no drinking water, and the parks authority publishes no admission price for the Judean Desert Nature Reserve. The reserve does have published hours, and entry closes an hour before they end, but there is nobody here to enforce them: the hours state when the authority considers the reserve safe to be in, not when a gate shuts.

Nothing on the mountain is a reconstruction, which is worth saying on a page in this series, because on most of them half the interest lies in telling the original from the rebuilt. Here the only human additions are the dirt roads, the trail blazes and a sign.

It is not remote from industry, though. The landmark the parks authority uses for directions in this stretch is the entrance to the Dead Sea Works, and the evaporation ponds that feed the potash plants are part of the view from the ridge. The Baltimore Sun filed its 1991 story from a working mining district, and the chief geologist quoted in it worked for the potash company.

For an overnight, the reserve has free unmanned camping at Mishor Amiaz: from Route 90 opposite the entrance gate to the Dead Sea Works, between kilometre markers 193 and 194, west onto the red-marked road, which the authority says any vehicle can manage, north about 2 kilometres, then round for another 2 kilometres to the camping ground. The surface can be too slippery for a private car straight after rain. Dogs are not allowed in the reserve.