Strange formations seen off Australian island raise questions: What caused them?
.png "The image, caught by a helicopter pilot, shows a series of serpentine circles undulating from the beach. The island in northeastern Australia is about 5 miles off the Queensland coast.")
A large, oddly serpentine shape photographed in the water off Australia’s Hinchinbrook Island National Park has prompted a social media debate among people scrambling for explanations.
The photo, taken by a helicopter pilot, shows an almost perfect pattern of emerald-colored circles undulating into darker blue water off the islands’ beach, 5 miles from the Queensland coast.
“This is something new and I love the look of it,” pilot Marije Kenter posted Jan. 21 on her Instagram page (@from.where.i.fly). “Anybody know how this gets formed?”
The ongoing debate, which spread from Instagram to Facebook, has included wild guesses, such as the possibility it was “freshwater filtering out through the sand.”
Such odd coastal shapes were often deemed “sea monsters” in centuries past, but modern marine biologists can now link them to shifting “bait balls” of fish ... or seafloor sediments stirred by large marine animals, McClatchy News reported.
However, the shapes spotted off Hinchinbrook Island are neither, according to an Instagram post by Tourism Tropical North Queensland, a nonprofit marketing agency.
It got curious about the mystery and says it consulted scientists with the Queensland Parks & Wildlife Service, who decided the photo is of “sand patterns ... caused by the interaction of very long period ocean waves called infragravity waves.”
These waves, which can be imperceptible to humans, travel at extremely slow rates, requiring up to 5 minutes to cross a distance “normal waves” achieve in just 6 seconds, the agency’s post reported.
The post didn’t explain how thewaves managed to create such a well-defined pattern, or why it appeared multiple times in one spot. Hence, there remains room for debate.
This story was originally published February 25, 2020 at 11:30 AM with the headline "Strange formations seen off Australian island raise questions: What caused them?."