Buzz
When we consider the oddities found on distant worlds that remain a mystery, it's easy to assume that we'd be able to unravel every secret if we could just reach them and study them up close. However, there are still many elements of Earth's own geological past that we can physically observe, yet still struggle to comprehend.
10. Mount Baldy Sinkholes
Standing at 37 meters (123 ft), Mount Baldy is the tallest sand dune along the southern edge of Lake Michigan. Indiana promotes this natural wonder as a 'living' dune because it shifts by a meter or two every year. The movement began after visitors trampled the grass that once kept it intact. While the wind is responsible for its motion, it's the dune's eerie ability to engulf children that has scientists stumped.
In July 2013, a six-year-old boy named Nathan Woessner was trapped when a 3-meter (11 ft) deep hole suddenly appeared beneath him. It took rescuers three hours to free him, fortunately alive. A month later, a second hole formed. Normally, deep air pockets don’t form in sand dunes because the sand should immediately fill in any voids.
“We’re witnessing what seems to be a new geological occurrence,” said Erin Argyilan, the geologist leading the investigation. She was working nearby when Nathan was swallowed and is personally committed to uncovering the cause.
The dune might cover trees, which decompose to create the holes. The site was previously mined for sand to be used in glass manufacturing, suggesting human activity may be contributing to the phenomenon. In the meantime, access to the dune is strictly prohibited.
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9. The Eye of the Sahara
The Richat Structure, also known as the Eye of the Sahara, spans 50 kilometers (30 miles) across the world’s hottest desert. It features concentric rings in varying shades of blue and is best observed from space. Initially believed to be an impact crater, recent studies strongly suggest that this theory is incorrect. Meteor strikes leave behind distinct compounds, including coesite, a form of silicon dioxide, but the Eye contains none of these.
Some have pointed out its resemblance to Plato’s descriptions of Atlantis, speculating that the lost city might have once been located there. However, even if Atlanteans had lived in the region, the structure itself is believed to have formed nearly 100 million years ago, well before any human civilization. Today, the only human presence there is a makeshift camp for daring tourists.
Another theory suggests that the Richat Structure could be the remnant of a volcanic formation, though its shape does not match the typical bulging dome expected of volcanoes. The prevailing hypothesis is that the feature was gradually shaped through erosion over an extensive period of time. While this explanation accounts for the surface features, the circular shape remains an unsolved mystery.
8. Desert Varnish
Rocks in desert regions are often covered by a thin layer that varies in color from light orange to black. Throughout history, people across the globe have created petroglyphs by scraping away this varnish. Despite its widespread presence, the exact process by which desert varnish forms remains a mystery.
The varnish is primarily composed of clay, with roughly a third of its content made up of iron and manganese, the elements responsible for its color and its ongoing enigma. Manganese, in particular, may be 50 times more concentrated in the varnish than in the surrounding environment. Laboratory studies have demonstrated that microorganisms can concentrate these elements. However, bacteria would produce this substance much faster than it naturally forms, which occurs at the rate of about the width of a human hair every 1,000 years.
Some scientists speculate that the varnish leaches from the rock or results from dust falling from the sky due to the excessive amount of silica, making a biological explanation unlikely. Others propose that the iron and manganese require life to form. A recent theory suggests that the varnish might be produced by microorganisms with an entirely different biochemistry. This hypothetical 'shadow biosphere' could have originated from a life form entirely separate from the common ancestor of the species we know today, potentially based on silicon instead of carbon.
7. Uturuncu
Uturuncu, a 6,000-meter (20,000 ft) volcano located in southwest Bolivia, last erupted 300,000 years ago. Satellite data from the past two decades reveals that the volcano’s underground chamber is filling up at a rate 10 times faster than comparable volcanic systems. It is accumulating magma at a rate of one cubic meter (35 cubic feet) per second. As a result, the land surrounding the volcano, within an area spanning 70 kilometers (43 miles), is gradually rising by a few centimeters each year.
The first unsolved question is how long the inflation process has been occurring. Geomorphologists have examined the surrounding terrain, which appears to be a relatively recent development, but much work remains to be done to uncover the full history.
The second enigma revolves around what Uturuncu will do next. Shan de Silva from Oregon State University, who has been researching the volcano since 2006, believes it could be a potential supervolcano. However, other geologists find no supporting evidence for this theory. Regardless, 300,000 years is the typical interval between eruptions in southwest Bolivia, and it seems that Uturuncu is preparing to make its move.
6. The Permian Extinction
The most catastrophic extinction event in Earth’s history was the End-Permian mass extinction. It is estimated that 93–97 percent of all species on the planet perished. The cause of this extinction remains one of the most hotly debated topics in paleontology.
Meteorites are often proposed as the culprits. A potential impact crater in Antarctica has been suggested, but the evidence for a meteorite collision is generally considered weak.
Volcanoes are another leading theory, with the Siberian Traps being the most likely candidates, having formed around the same period. Researchers studying the extinction boundary in Canada discovered a layer of coal ash and hypothesize that volcanic activity ignited vast coal fields, triggering a runaway greenhouse effect. Even without the fires, the volcanoes could have released sulfates into the atmosphere, blocking sunlight and creating intense acid rain.
Volcanism might have also had a more indirect impact. MIT researchers have pointed to a microbe called Methanosarcina, a single-celled archaea that thrives on nickel and carbon dioxide, both of which were abundant due to volcanic activity. These microbes produce methane, a greenhouse gas 30 times more potent than carbon dioxide, which could have led to extreme global warming.
5. Lake Hillier
Lake Hillier is one of the most mysterious pink lakes in the world. Though not the only one, it remains the least understood. First discovered in 1802, it sits in a pristine region of Australia's wilderness. To protect the wildlife living around the lake, it's only accessible by air, leaving much of it untouched by research.
Known for its 'bubblegum pink' hue, the lake is safe for swimming, though its waters are extremely salty. Experts have proposed three main theories to explain its unique color, based on what we know about other pink lakes around the world.
Pink Lake, found in Western Australia, features a less intense pink shade and is located in hillier terrain compared to Lake Hillier. Its coloration is attributed to a mix of shrimp and microorganisms called halobacteria (although they are not true bacteria). It's possible that similar microorganisms, or archaea like halobacteria, could inhabit the salt crusts of Lake Hillier.
Lake Retba in Senegal, which also has a pinkish hue and a high salt content, owes its color to algae.
Lastly, the pink color of Lake Hillier might not be the result of life at all, but rather from chemical reactions. The salt in the lake could react with dissolved baking soda, or perhaps the surrounding rocks have a unique composition contributing to the striking hue.
An optical illusion is definitely not the cause, as the water remains pink even when placed in a bottle.
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The Hawaiian Islands were likely created by a geological phenomenon known as a 'hot spot.' These are areas where magma rises to the Earth's surface and stays there for millions of years, as tectonic plates move over them. This process results in the formation of a chain of volcanic islands, with the youngest one hosting an active volcano. Hot spots account for about 5 percent of all volcanoes located far from tectonic plate boundaries.
The Hawaiian Island chain is one of several believed to have formed due to a 'hot spot.' In these regions, magma rises from deep within the Earth, creating volcanic islands as continental plates drift overhead. This phenomenon is responsible for the volcanic activity in the region and contributes to the creation of new land over tens of millions of years.
The origin of hot spots remains one of geology's greatest unsolved questions. The dominant theory proposes that they are caused by a plume of extremely hot magma rising from deep within the Earth, potentially from the boundary between the mantle and the inner core, around 3,000 kilometers (1,800 miles) below the surface. These are referred to as mantle plumes, although there's still no consensus on whether they truly exist. Research in labs and theoretical models suggest they might be possible.
In 2011, a team from MIT released a study proposing that a thermal anomaly located 725 kilometers (450 miles) west of Hawaii might be a more plausible source and could be situated only 800 kilometers (500 miles) beneath the surface. This pocket of molten material would have traveled along the top of the mantle before rising through the crust.
3. Messinian Salinity Crisis
Approximately six million years ago, the Mediterranean Sea underwent a dramatic transformation, turning into a desert. This arid phase lasted for about 630,000 years and is known as the Messinian Salinity Crisis. While it's widely accepted that the sea was cut off from the Atlantic Ocean, the real mystery lies in understanding exactly how this happened, with multiple theories offering potential explanations.
One theory suggests that an expansion of the polar ice caps caused sea levels to drop, creating a land bridge that blocked the Mediterranean's access to the Atlantic. Another possibility is that tectonic shifts elevated the seabed near Gibraltar, similar to the forces that uplifted the Alps, potentially squeezing Spain and Morocco together and closing off the strait.
A more unconventional hypothesis proposed by geologists at Royal Holloway University of London suggests that the Atlantic Ocean floor may have peeled up. This shift caused a flap of the ocean floor to remain connected at its western edge, allowing lighter rocks beneath to rise up. These rocks eventually settled in place, forming a massive natural barrier across the Gibraltar Strait. The dam held until the sea rapidly flooded the area again, about half a million years later.
2. Low-Angled Normal Faults
A fault refers to a crack in the Earth's surface, with the two sides of the crack potentially moving in various directions. Most faults aren't vertical, and the side that sits above is termed the hanging wall, while the lower half is the footwall. A slip-dip fault occurs when the hanging wall moves either up or down in relation to the footwall, and such faults are typically very steep.
Slip-dip faults where the hanging wall moves downward are called normal faults. When these faults have a shallow slope, less than 30 degrees from the horizontal, they are classified as low-angle normal faults, or LANFs. LANFs pose a problem because they shouldn't even exist. Our models predict that if they form, they should lock up and evolve into steeper faults. They've been dubbed as “the greatest paradox of tectonics.”
LANFs are expected to lock because the friction between the two sides should prevent movement. Typically, when a fault locks, it builds up strain until an earthquake occurs, breaking through the friction. However, LANFs have never been shown to cause earthquakes, and it seems likely that they don’t. This makes them the only known fault type to move only through gradual creeping.
This leads to significant gaps in certain important geological models. Alternatively, our laboratory measurements of fracture and friction might simply not correspond to real-world conditions in the way we expect them to.
1. The Grand Canyon’s Age
The Grand Canyon stands as one of the planet's most iconic geological features. It's also among the most intensely studied. Despite this, there remains no agreement on its exact age, and the debate isn't over just a few years. Some scientists argue it’s about six million years old, while others claim it could be as much as 70 million years old.
The two opposing views center on whether the Colorado River carved the canyon or if the canyon existed beforehand and the river simply cut its path through it. Researchers continue to publish papers advocating each side, yet progress remains limited.
