2 days ago
Incredible and 'rare' phenomenon on quiet Aussie beach vanishes within 24 hours
A dog walker strolling along a rugged Australian beach was 'amazed' to stumble across a sprawling natural phenomenon few people are lucky enough to witness.
While Sybil Jethro thought the formation resembled ancient stalactites, which grow slowly at 10cm every thousand years, experts believe the strange sand flow she photographed likely materialised in milliseconds.
Sybil spotted the gnarled shapes in the sand on Sunday morning at Ocean Beach, a wild 37km stretch of sand on Tasmania's west coast. They were just two metres from the water's edge, and directly below a bank of mud or peat.
'I'd say it was as big as a couple of tables, big eight-seater dining room-sized,' she told Yahoo News Australia. 'I couldn't quite work them out. They were close to the water line, so I'm pretty sure the next high tide will just wash them away.'
Related: 🦀 Incredible sand formations created by sand bubbler crabs
How were the sand formations created?
The formations in her pictures have been described as resembling seaweed, tongues, and even caterpillars. But Professor Patrick Hesp, an expert in coastal geomorphology at Flinders University, has settled on the description of 'tongues'.
He explained it's 'rare' to see formations as large as these. They form quickly during a sudden inundation of water onto the sand and are quickly destroyed by the tides or more rain.
When a bed of sand is suddenly soaked with water, it can form dozens of these long, flowing 'tongues' which then move down the hillside. Professor Hesp compares them to debris flows that occur after heavy water flows turn loose soil, rock and organic matter into a slurry, but in this case, they're much smaller.
Their lifespan is short because as they move over sand that's less wet, the moisture sinks below, drying out the tongue above.
'People don't think sand dunes have much water influence, but at times, you get quite significant sheet wash. This means the water is flowing across the surface and washing a fan of sand down,' Professor Hesp explained.
'But on occasions it's more localised, and it produces these saturated flows that just lose all their water suddenly and stop in place.'
Replacements form after 'tongues' vanish
After returning to Ocean Beach on Monday morning, the original sand tongue Sybil photographed was gone.
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But already there were new ones forming along the coastline. Although they aren't as intricate as her weekend find, her images help illustrate how these incredible structures form.
With her dog sitting on the sand for scale, you can see large globs of sand rolling down the bank.
Incredibly, the sand tongues were just 1.5km from where Sybil photographed a rare oarfish in June, also known as a "doomsday fish". While its discovery created national media attention, she was likely the only person to witness the intact fish before it was torn apart by scavenging birds.
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