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The Mysterious Holes in Indiana’s Sand Dunes

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Something strange is happening on one of Indiana’s sand dunes. Holes, about a foot wide and as much as 11 feet deep, are opening up in the sand on Mount Baldy at Indiana Dunes National Lakeshore, and then vanishing within a day.

The holes made themselves known in the worst way: One swallowed a six-year-old boy last summer, burying him under 11 feet of sediment for hours. He survived, but the incident prompted the National Park Service to close Mount Baldy to the public indefinitely. Almost a year later, at least two other holes have opened and closed, and 66 anomalies have been detected in the sand.

Video shows researchers using long sticks to poke at “soft spots”—depressions in the sand where holes could open up. Grains of sand disappear into the 126-foot tall dune as if being sucked into the bottom half of an hourglass. It’s enough to make one shiver, conjuring up terrifying thoughts of being buried alive. Scarier still: Researchers don’t know for sure what’s causing the holes.

"We're seeing what appears to be a new geological phenomenon," says geologist Erin Argyilan, who has been studying the holes for several months.

But there is a working theory. The dune currently sits on top of what was once a forest, and the thought is that trees buried beneath the sand for the last century are rotting and disintegrating, leaving holes where the trunks once were. "The age of the materials and the wet conditions during the spring of 2013 may have forced these materials to become unstable, collapsing and creating openings to the surface," says the park's website.

Mount Baldy is one of Indiana’s fastest-moving dunes. The wind causes it to move between 11 and 20 feet to the south each year, park ranger Bruce Rowe tells mental_floss. “We have seen evidence of trees that have been uncovered before as the dune moved on,” Rowe says. “But in the past they were always partially decayed stumps of trees. They were called ghost forests. They fell apart as they were exposed to the air. But the idea of holes rather than stumps is completely new to science.”

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It’s also baffling because, until now, dunes were considered solid structures. “We contacted various coastal dune specialists, and one of them said, ‘If I hadn’t heard this had actually happened from you, I’d say it was impossible,’” Rowe says.

So what’s to be done? This summer, a team of researchers will use ground-penetrating radar to map the dune’s thickness and identify potential openings at its base, and take core samples to identify materials within the dune. Dr. G. William Monaghan, a geologist and geoarchaeologist with the Indiana University Glenn A. Black Laboratory of Archaeology, says they also hope to use an unmanned aerial vehicle (a.k.a. a drone) equipped with lasers that can accurately map the area’s topography and identify changes. “...Or we’ll see if there’s a void down there,” Monaghan adds. “In a way we’re not sure what we’re gonna see until we’re out there seeing it.”

Until researchers get to the bottom of the mystery, Mount Baldy will remain closed. “This has become a really fascinating science mystery that’s playing out in our park,” Rowe says.

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Live Smarter
Researchers Say You’re Exercising More Than You Think
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They say a journey of a thousand miles starts with a single step. If the thought of a thousand-mile journey makes you tired, we've got some great news for you: You've probably already completed one.* A new study published in the journal Health Psychology [PDF] finds that people underestimate the amount of exercise they're getting—and that this underestimation could be harmful.

Psychologists at Stanford University pulled data on 61,141 American adults from two huge studies conducted in the 1990s and the early 2000s: the National Health Interview Survey and the National Health and Nutrition Examination Survey. Participants answered questionnaires about their lifestyles, health, and exercise habits, and some wore accelerometers to track their movement. Everybody was asked one key question: "Would you say that you are physically more active, less active, or about as active as other persons your age?"

The researchers then tapped into the National Death Index through 2011 to find out which of the participants were still alive 10 to 20 years later.

Combining these three studies yielded two interesting facts. First, that many participants believed themselves to be less active than they actually were. Second, and more surprisingly, they found that people who rated themselves as "less active" were more likely to die—even when their actual activity rates told a different story. The reverse was also true: People who overestimated their exercise had lower mortality rates.

There are many reasons this could be the case. Depression and other mental illnesses can certainly influence both our self-perception and our overall health. The researchers attempted to control for this variable by checking participants' stress levels and asking if they'd seen a mental health professional in the last year. But not everybody who needs help can get it, and many people could have slipped through the cracks.

Paper authors Octavia Zahrt and Alia Crum have a different hypothesis. They say our beliefs about exercise could actually affect our risk of death. "Placebo effects are very robust in medicine," Crum said in a statement. "It is only logical to expect that they would play a role in shaping the benefits of behavioral health as well."

The data suggest that our ideas about exercise and exercise itself are two very different things. If all your friends are marathoners and mountain climbers, you might feel like a sloth—even if you regularly spend your lunch hour in yoga class.

Crum and Zahrt say we could all benefit from relaxing our definition of "exercise."

"Many people think that the only healthy physical activity is vigorous exercise in a gym or on a track," Zahrt told Mental Floss in an email. "They underestimate the importance of just walking to the store, taking the stairs, cleaning the house, or carrying the kids."
 
*The average American takes about 5000 steps per day, or roughly 2.5 miles. At that pace, it would take just a little over a year to walk 1000 miles.

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Medicine
Scientists Are Working on a Way to Treat Eye Floaters With Lasers
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Even people with 20/20 eyesight should be familiar with this scenario: You're enjoying a clear view when a faint doodle shape drifts into your peripheral vision like an organism under a microscope. Floaters affect almost everyone, but there's currently no medically accepted, non-invasive way to treat them. Two doctors with Ophthalmic Consultants of Boston are working to change that. As IFLScience reports, the team believes that lasers may be the solution to bothersome eye squiggles.

As Chirag Shah and Jeffrey Heier write in their study in the journal JAMA Ophthalmology, lasers can be used to safely combat the underlying causes of floaters. Also known as muscae volitantes, Latin for “hovering flies,” the condition comes from physical debris leaking into your eyeball. The front of your eyes is filled with a liquid called vitreous humor, and when drops of that gelatinous substance break off from the whole, the bits cast shadows on your retinas that look like gray blobs. Because floaters literally float inside your eyes, trying to focus on one is almost impossible.

These spots aren't typically a problem for young people, but as you get older your vitreous humor becomes more watery, which increases the chance of it slipping out and clouding your vision. Retinal detachment and retinal tears are also rare but serious causes of symptomatic floaters.

Shah and Heier tested a new method of pinpointing and eliminating floaters with a YAG laser (a type of laser often used in cataract surgery) on 36 patients. An additional 16 test subjects were treated with a sham laser as a placebo. They found that 54 percent of the treated participants saw their floaters decrease over six months, compared to just 9 percent of the control group. So far, the procedure appears be safe and free of side effects, but researchers noted that more follow-up time is needed to determine if those results are long-term.

At the moment, people with symptomatic floaters can choose between surgery or living with the ailment for the rest of their lives. YAG laser treatment may one day offer a safe and easy alternative, but the researchers say they will need to expand the size of future studies before the treatment is ready to go public.

[h/t IFLScience]

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