On April 25th, 2018 we learned about

Mini model meteorites demonstrate how well hot rocks can deliver water to dry planets

While we live on an impressively wet planet today, the Earth probably didn’t start out with our lush collections of rivers, lakes and oceans. With no obvious way for the planet’s iron and other minerals to have spontaneously transmuted into H2O billions of years ago, scientists have long suspected that our water was instead delivered from space via icy objects like comets. Further research found that our water looked more like the water found on icy asteroids like Ceres, which was clearly abundant in the asteroid belt, but it still posed a problem. Asteroids tend to burn and explode a lot when they get too close to the Earth, so how would any of their water survived long enough to help soak our planet?

Proxy-asteroid projectiles

With no asteroids or spare planets at their disposal, researchers from Brown University turned to the Vertical Gun Range at the NASA Ames Research Center to simulate icy impactors. Marble-sized projectiles were fabricated to match the composition of carbonaceous chondrites, or meteorites suspected of being formed in ancient, icy asteroids. The miniature proxy-meteors were then fired at a chunk of dry pumice powder, which served as their stand-in for the once-parched surface of the Earth.

The small impactors hit their targets at more than 11,000 miles-per-hour, releasing heat and an impressive amount of debris in all directions. As with real asteroid impacts, enough heat was generated in these collisions to outright destroy some material, including some of the water ice. However, some of the mineral content also melted, which weirdly enough was key to some of the water’s survival. Because the rock melted and re-cooled so quickly, it could capture some of the water inside the resulting glass, keeping it “safe” from vaporizing. Additional water was similarly captured by flying breccias— random debris thrown and heated by the impact that were hot enough to become “welded” together.

Making sense of previous predictions

This experiment not only helps explain some of the water on Earth, but also some of the confusing H2O around the solar system. Since previous estimates found that asteroid impacts should vaporize water, researchers had a hard time explaining the presence of water in impact craters on places like the Moon and Mercury. The physical test proved that those estimates hadn’t captured the full complexity of such an impact, and that delivering water via screamingly-fast hunks of icy rock is apparently more practical than you might think.

My five-year-old asked: What does the Vertical Gun Range look like?

“Gun” may be a misleading term here, because the equipment in question doesn’t really look much like pistol, rifle or cannon, at least outside science fiction. A large barrel launches a projectile into an enclosed, reinforced chamber. That chamber is outfitted with a number of sensors and cameras so that researchers can learn more details about the behavior of whatever collision is being studied. NASA has more on the AVGR in this handy PDF.

Source: Projectile cannon experiments show how asteroids can deliver water by Brown University, Phys.org

On April 19th, 2018 we learned about

A meteorite delivered diamonds carrying traces of our solar system’s less successful protoplanets

Building a planet out of dust isn’t easy. Sure, the recipe basically requires innate forces like gravity to do a lot of the work, but not every clump of debris successfully forms into a durable planet. Those first steps are called protoplanets, and while we’ve seen them around other stars, we’ve only recently found evidence of the protoplanets that helped build the planets in our own solar system.

Learning from dirty diamonds

The evidence found in diamonds carried to Earth in a meteorite that struck the Earth in 2008. Those diamonds carried small bits of other metals and minerals that were present when the diamond was formed. The composition and structure of this extra material, known as inclusions, can tell us a lot about the conditions that created the diamond.

In this case, the structure of the diamond indicates that it was formed as an achondrite— a rock formed in an object large and hot enough to create a metallic core inside a layer of rock. That could include very large asteroids, but other features of these diamonds make it more likely to have been formed in a larger protoplanet instead. The inclusions also show that these diamonds were formed under at least 20 gigapascals of pressure, well beyond diamond’s normal elastic breaking point. With that reference point, geophysicists can estimate that the protoplanet that created these diamonds was somewhere between the size of Mercury and Mars.

This may seem like a crazy amount of information to infer from a single space rock, but we’ve been reading history from diamonds here on Earth for years. Actually, we’ve been getting history out of the Earth, as diamonds are known to carry information about the formation and movement of materials deep under the Earth’s crust, carrying them to the surface like shiny time-capsules, including deposits of water over a 100 miles below the Earth’s surface.

Potential planets from the past

None of this suggests that we have a new planet forming next door. Simulations of our solar system’s formation predicted that multiple protoplanets formed within 10 million years of our Sun’s formation. While at least eight of those objects managed to survive long enough to become the planets we know today, the diamonds found in the 2008 meteorite are probably just pieces of some of the other protoplanets that were destroyed in collisions in a more crowded solar system.


Source: Diamonds in Meteorite May Hail from Our Ancient Solar System by Doris Elin Slazar, Space.com

On April 1st, 2018 we learned about

Satellites can spot underground supplies of volcanic magma from space

The best way to find volcanic activity brewing under the ground may be to look from space. While magma and gas aren’t directly visible until a volcano actually erupts, their accumulation underground can cause the ground surrounding a volcano to deform. These deformations aren’t necessarily big enough to be noticed by the naked eye, they can be detected by special GPS sensors staked in the ground surrounding the volcano. However, these sensitive instruments can’t be everywhere at once, which is why researchers from Penn State are looking into looking for these subtle shifts in the ground from over 1000 miles above the Earth’s surface.

While a lot of information can be gleaned from visual photography, the imaging in this study was actually a form of radar. Known as Interferometric Synthetic-Aperture Radar (InSAR), this technology creates topographic maps precise enough to show changes in elevation as small as a one-third of an inch. This allowed them to track a three-inch bulge in the ground north of the Masaya volcano in Nicaragua which was attributed to a growing pool of magma that was otherwise undetected. It’s not that the traditional GPS monitors weren’t sensitive to these shifts, but that they just didn’t have the range of satellite imaging, and thus couldn’t pick up on changes in the ground two miles away from the volcano’s open crater.

Better predictions from bigger pictures

This wider range of detection then offers a number of benefits. By monitoring a larger swath of territory, we increase the odds that we’ll detect deformations in terrain that could predict eruptions before people are in danger. The Masaya volcano is known to have blasted ash and lava in a radius of 30 miles during a 1772 eruption, which is probably the kind of thing the two million people that now live within 12 miles of the volcano would like to be ready for.

Beyond human safety, getting more data about volcanic activity will help researchers better understand how volcanoes work in the first place. A build-up of magma two miles from the actual volcano shows that there’s a lot more to these systems than the cone we see on the surface. If more of that system can be tracked and measured with a satellite, it will help build more accurate models about how magma and pressure leads to eruptions in the first place. That will then make future observations, possibly from space, all the more useful in predicting eruptions in other locations around the world.

Source: Wider coverage of satellite data better detects magma supply to volcanoes by David Kubarek, Penn State News

On March 15th, 2018 we learned about

Burning coal was likely the key component of the world’s worst extinction event

As dramatic as a good asteroid strike can be, giant falling space rocks aren’t the only thing that has wiped out life on Earth. The mass extinction that ended the Age of Dinosaurs was actually the fifth time nearly everything died. Before the first dinosaur was ever born, an extinction event known as “The Great Dying” took place, a horrific series of events that choked, poisoned or burned multitudes of animals on both the land and in the seas. 70 percent of terrestrial vertebrates and 90 percent of sea life went extinct during this time 252 million years ago, with the devastation taking at least 10 million years to show signs of recovery. While many of the terrible details about how things died have previously been discovered, research out of Utah is helping piece together what started all this destruction in the first place.

Indirect effects of eruptions

With no sign of an asteroid strike in sight, researchers have been looking for other events that might have knocked the world’s climate and atmosphere so far out of balance that it became toxic for most creatures to breathe. There’s evidence that massive volcanic eruptions took place in Asia around the end of the Permian period, but they predated the fossil records of the Great Dying by 300,000 years. Furthermore, analysis of rock layers from Utah don’t show signs of direct volcanic impact at that time— instead of the metals like nickel that you’d expect to  be carried from underground by a volcano’s magma, deposits from the end of the Permian have extra mercury, lead and carbon-12, all of which are associated with burning coal.

The picture that then emerged was one where volcanic eruptions were a trigger for The Great Dying, but not the exact cause, as their ash wasn’t influential enough to reach around the world, such as to what is now Utah. Instead, the erupting lava seems to have hit and ignited massive coal beds that were originally deposited in Asia in the Carboniferous period. As that coal burned, it spread around the world, setting off the bigger chain of events that led to mass extinctions.

From coal to corrosion

The fallout from the burning coal might be enough to make a prehistoric therapsid dream of asteroid strikes. The soot from the coal led to severe changes in the planet’s climates, raising temperatures, and acidity, of the oceans. As the oceans warmed, barium levels indicate that more methane was released from the sea floor, trapping even more heat in the atmosphere. After all this, an abundance of pyrite that was formed at this time suggests that the oceans became depleted of oxygen, naturally leading to more dead marine animals. Those deaths were so abundant that the bacteria that set to work consuming corpses released an immense amount of hydrogen sulfide gas (H2S), bringing us to what happened to the poor creatures living on land.

Hydrogen sulfide gas is toxic in large doses, but more importantly can react with moisture in the air to form acidic sulfur dioxide (SO2). So as bacteria tried to clean up the oceans, their waste led to acid rain that started killing plant life on land. Between the toxic, burning atmosphere and a lack of plants, the food chain understandably would have collapsed, taking both herbivores and the carnivores that ate them with it.

Current costs of burning coal

The scariest part of all this is probably just how mundane the idea of burning coal seems today. Thanks to industrialization, we don’t even need the help of a volcano to burn massive amounts of the stuff around the world. Thankfully, air quality legislation has managed to take steps to reign in acid rain, so we’re not corroding our forests into pulp right now. However, the seas do seem to be starting to relive some of the Great Dying, as temperatures and pH levels have been rising in various patches of the ocean. Thankfully, unlike a volcano or asteroid strike, there’s more we can actually do to head off The Great Dying II, because that’s definitely a sequel nobody wants to ever see.

Source: Burning coal may have caused Earth’s worst mass extinction by Dana Nuccitelli, The Guardian

On February 21st, 2018 we learned about

Tsunamis may soon be detected with a single hydrophone and a decent amount of math

Tsunamis aren’t subtle, but they do still manage to be surprising. They’re created by earthquakes under the sea, sometimes so far from a coast that people will have no idea any seismic activity occurred. Then, once the surge of water reaches a shoreline, anyone there has very little time to react and escape the area. As we get better at monitoring the ocean floor for earthquakes, these events are becoming slightly easier to predict, but the sea floor is so vast that it’s not the most practical endeavor. However, new research is suggesting that the key to catching tsunamis earlier may come down to listening to the sea, and acoustic gravity waves in particular, in just the right way.

Massive amounts of movement

When an earthquake occurs in the ocean, there’s obviously a lot of shaking and vibrating going on. In addition to massive amounts of displaced water, a quake will send out acoustic gravity waves (AGWs) in every direction. These waves are a bit like a hybrid of sound waves moving laterally through the air, and the gravity-sensitive waves you see shaping fluids like the average waves near a beach. This has made AGWs tricky to study and model, since they don’t follow the exact patterns we see in more common wave activity. One trait that has stood out, however, is that an AGW can move through the ocean at the speed of sound across huge distances. Because of their impressive sizes and speeds, researchers have long hoped that they could be detected well in advance of a tsunami’s arrival, buying people more time to get to safety.

The difficulty hasn’t been detecting the AGWs, but making sense of them. Fortunately, scientists from the University of Cardiff are now suggesting that this kind of analysis is not only possible, but practical even with only a single hydrophone sensor in the ocean to detect the wave. The distinct shape and speed of any AGW should reveal various aspects about the earthquake that created them. With more information in the system, such as details about the suspected fault location, researchers state that the tsunami’s amplitude and potential impact on a shoreline can be predicted. Once compiled, these data could then be used to trigger tsunami alarms in the tsunami’s path, giving people crucial time to find safety.

Heard through single hydrophone

On a basic level, this is similar to the tsunami alarms we have today. Devices known as dart buoys are anchored at sea, and can then detect unusual pressure changes in the water below them. This works if the buoys are in the tsunami’s path, which then requires that they’re located in all the right locations at all the right times. Measuring AGWs, however, don’t require that kind of specific placement. Because AGWs expand in multiple directions from an earthquake’s epicenter, hydrophones in any direction could detect clues about the formation of a tsunami. This then leads to a much more practical system for early warnings, increasing the chances that an alarm will reach people with enough time to get away from the water.

Source: Could underwater sound waves be the key to early tsunami warnings? by Cardiff University, Science Daily

On January 15th, 2018 we learned about

Sifting through the causes, concepts and misconceptions of quicksand

Despite growing up in tame suburban landscape of sidewalks and lawns, my kids are very concerned about how to deal with quicksand. I can only assume that repeated viewings of Wreck It Ralph and The Force Awakens (no Princess Bride yet) have helped build up the mystery of watery sand, particularly since fiction usually portrays it as something perilous that can capture a hero without warning. Of course, having seen DuckTales and G.I. Joe, I know that my kids’ concerns are unfounded, and that we’ll never run into quicksand near our home. Or so I thought.

Sources of soupy sand

Well, I was right about the general composition of quicksand. It’s any loose, grainy soil with a large concentration of water in it to turn it into a fluid. One of the most common places to run into quicksand is at the beach when water rushes into loose sand. Sand that’s only moist is likely to clump together, but with enough water flowing through the sand, each grain will separate and basically roll around independently of each other. The resulting soup can then look like solid ground from above, but has a consistency just a bit thicker than water when you step into it. While quicksand in nature is going to involve water, Mark Rober has a great demonstration of how sand can behave like a fluid using air as well.

Now, not every puddle turns into quicksand, obviously, mainly because the water needs to flow in a way that helps separate the grains of sand or soil. A great way to break up clumped soil turns out to be vibrations from earthquakes, and tremblors are a major cause of quicksand in all kinds of environments. Quake-produced quicksand is actually a significant safety hazard, not so much for people suddenly in need of conveniently placed vines, but for buildings that partially sink into the ground, stressing or warping their structural integrity. As such, researching the exact combinations of vibrations, soil composition and water flow has been the subject of research looking to predict which locations are most likely to suddenly turn to soup when the ground shakes.

Saving yourself from sinking

Aside from our next trip to the beach, the intersection of quakes and quicksand adds sudden legitimacy to my kids’ concerns about sinking into the soil. We don’t live especially close to a marsh or lake, but earthquakes aren’t uncommon in the Bay Area. Unless a water pipe bursts at just the right spot, it still seems unlikely that we’ll run into quicksand nearby, but there aren’t many conveniently placed vines to grab hold of if we did. Despite what cartoons and movies have taught us, that’s probably ok, since most quicksand isn’t likely to swallow you up in the first place.

While drowning in fluidized soil can happen, most instances of quicksand in nature aren’t that deep, so you aren’t likely to be fully submerged in order to drown. You might get stuck though, and trying to lift your legs straight up to take a step would be very difficult. Your best option is to try to lean back and spread your arms, letting buoyancy help lift you up. Small movements of your legs will help loosen them, but sharp vertical yanks aren’t going to be practical. This isn’t to say that people don’t die after getting stuck in quicksand, but some of those cases are due to other factors, like rising water levels, than the quicksand on its own.

Source: How Quicksand Works by Kevin Bonsor, How Stuff Works

On January 4th, 2018 we learned about

Fossilized microbes show surprising biodiversity from 3.4 billion years ago

Most rocks on the Earth’s surface don’t last more than 200 million years before erosion or other forces get the best of them. Sure, that’s older than any dinosaur, but it’s only a tiny slice of our planet’s 4.5-billion-year history. Thankfully, rocks and crystals from the Earth’s early days do turn up here and there, helping us understand what our planet once looked like, and even more intriguing, who first called it home. That latter point is being revealed by 3.4-billion-year-old rocks from Australia, which have been found to not only contain fossilized microorganisms, but evidence of a surprisingly diverse ecosystem at a time when our planet was just beginning to be habitable.

Combing through fossils for traces of chemistry

The fossilized microorganisms weren’t multicellular animals of course, so these ancient rocks offered no bones or organs to study. Instead, researchers studied each singled-celled organism with secondary ion mass spectroscopy (SIMS). This technology allowed researchers to compare variations of carbon atoms, or isotopes, in the fossils and surrounding stone. The ratios of carbon-12 to carbon-13 was then be used to determine how each microbe functioned when it was alive, as those isotopes will accumulate differently in different metabolic conditions.

Differences in these early prokaryotes‘ metabolisms suggest that even 3.4 billion years ago, life had evolved a few different ecological niches. One group was apparently a methane producer, while another powered its metabolism by consuming methane. A third fossil showed signs of primitive photosynthesis that, unlike today’s plants, didn’t produce oxygen (which would have been toxic to these organisms). A microbe from an earlier study rounds out the bunch, as it relied on sulfur as its primary food-source.

Is life less unusual than we assumed?

This version of Earth certainly wouldn’t be habitable by today’s standards, but it’s an amazing degree of sophistication for a planet that had probably only had solid ground for 600 million years. This suggests that either the Earth was intensely lucky at an early age, or that life may be a bit more tenacious than we once thought. If it’s the latter, researchers suspect that this aggressive microbial timeline may have played out on other planets as well. It wouldn’t mean that other planets have the same complex organisms we do here, but that getting some microbes growing in the first place isn’t such a long-shot.

Until we get probes out to places like Europa, Titan or Enceladus, the best location to find extraterrestrial microbes may be Mars. This wouldn’t be to find microbes alive today, but to look for traces of similar fossils from the days when Mars was likely a more habitable planet.


On November 27th, 2017 we learned about

Most of the mammoths found trapped in hazardous terrain turn out to be male

One of the most important features of the La Brea Tar Pits in Los Angeles are the traffic cones. The museum’s collection of Pleistocene animals is great, as are the continuing excavations taking place at the site, like Project 23. However, having just returned from my kids’ first visit to the Tar Pits, I think the entire experience was greatly enhanced natural liquid asphalt bubbling out of the ground in the surrounding Hancock park. Some bigger pools are fenced off, but it’s clear that the asphalt is slightly unpredictable, sometimes oozing outside a barrier, or simply popping up in the middle of the lawn, with only an oil-splattered traffic cone to warn you of its sticky presence. It all helps drive home just how animals living in the Los Angeles basin 60,000 years ago might have gotten into trouble without the bright green cones in place to warn them.

The La Brea Tar Pits weren’t the only natural hazards Ice Age animals had to worry about, and a recent study of mammoth (Mammuthus primigenius) remains from Siberia looked for patterns in which creatures most often got themselves into these sticky situations. Excavations of geological dangers like asphalt pools and icy lakes had already established that one trapped herbivore was likely to attract huge numbers of carnivores (that would also end up trapped), but this study looked to see which particular mammoths couldn’t stay out of the asphalt, ice or other pitfall. Since these animals were well preserved from only 60,000 years ago, DNA from hair and bones could be used to determine that 69 percent of the trapped mammoths were male, despite having originated from a balanced population.

Males in the muck

Researchers suspect that, if mammoths follow some of the behaviors seen in their modern elephant relatives, the unusual sex-ratio was due to male mammoths’ inexperience. Elephants today generally rely on the leadership of an older female, and that matriarch retains and transmits information about everything from when to migrate to how to avoid hazards in their environment. Young male elephants have to figure all this out themselves, even if it means finding out the hard way.

If mammoths lived in a similar manner, the males likely fell into pits and asphalt pools more often because they had nobody to teach them until it was too late. A higher tolerance for risk may have also made them more likely to try stepping on the weird black stuff in the grass, since without a matriarch or green traffic cone to warn them, they weren’t sufficiently wary of what now seems like an obvious danger.

My third grader asked: What’s the asphalt made of?

liquid asphalt bubbling up in Hancock Park
Liquid asphalt bubbling up in Hancock Park, Los Angeles.

While male mammoths were apparently adept at getting stuck in all kinds of hazards, the pachyderms in what would become Los Angeles were stuck in a natural asphalt, which is the lowest grade of crude oil. This oil is a layer of decomposed, pressurized marine plankton, first laid down five to 25 million years ago. The bubbles are generally methane gas, although microorganisms in the oil help create hydrogen sulfide, which adds a notable “rotten egg” smell.

It’s not clear how ancient mammoths missed the bubbles and the smell, but once dust and leaves covered the surface of a shallow oil pool, it seemed to only take a few steps to completely ensnare mammoths and other megafauna.

Source: Woolly Mammoth Bachelors Skew the Fossil Record by Carl Engelking, D-brief

On November 2nd, 2017 we learned about

Sediments suggest that the asteroid that destroyed the dinosaurs also triggered years of freezing temperatures

You’d think that mass extinction would be devastating enough, but every new detail that scientists uncover about the asteroid impact that wiped out the dinosaurs seems to somehow make a bad situation even worse. To the best of our knowledge, a six- to nine-mile-wide asteroid hit the Earth near the Yucatan Peninsula 66 million years ago, kicking off a series of catastrophes that resulted in the death of 75 percent of all living things. To glean even more detail about this traumatic event, scientists have been analyzing the rock and soil that was laid down at the time of impact in what’s known as the Chicxulub impact crater. What they’ve found is that on top of everything else, the world was plunged into a deep freeze that lasted up to three full years. And if that somehow wasn’t enough, there’s also a good chance that the whole thing stunk like a bad fart.

When the asteroid hit the Earth, so much debris was kicked up that it left a clear layer of sediment around the world, now known as the Cretaceous-Paleogene boundary. The rock layers at the crater itself offer a more granular picture of how this debris was distributed though, even revealing the exact angle of the asteroid’s impact. By comparing differences in composition on either side of the crater, researchers calculated that the asteroid was traveling at around 40,000 miles per hour, striking what was once a shallow sea at around a 60 degree angle. It instantly created an 18-mile-deep hole, although that pit was short lived as the walls collapsed inwards within minutes of the collision.

Sulfur saturates the skies

Beyond the crater itself, gigatons of material from the Earth and asteroid were vaporized in this violent process. Thanks to these new samples, researchers have amended earlier estimates about the composition of this material, all of which point to a colder, stinkier way to die. Smaller amounts of sulfur are associated with the smell of rotten eggs or fragrant hot springs, and can be combined in to poisonous compounds under the right conditions. In this more cataclysmic scenario, thousands of billions of tons of sulfur were ejected into the atmosphere, blanketing the planet in a layer of noxious gas thick enough to block sunlight. This general model isn’t new, but the amount of sulfur in these new figures far exceeds previous estimates. Instead of simply making photosynthesis difficult for plants on a darkened world, it’s now thought that global temperatures dropped by 47° Fahrenheit, dropping below freezing in many locations. This instant winter then lasted for at least three years, but possibly well over a decade.

The other measurement to come out of this visit to Chicxulub didn’t soften things at all. Looking at carbonates as a measure for the amount of carbon dioxide released during the asteroid’s impact, researchers realized that previous estimates had been too generous. There was still an impressive 425 gigatons of CO2 released, but that wasn’t enough of the greenhouse gas to really counteract the cooling effects of the sulfur in the air. Eventually things warmed up again, but the immediate jolt to global temperatures was clearly too much for most ecosystems to survive.

Source: Asteroid impact plunged dinosaurs into catastrophic 'winter' by Jonathan Amos, BBC

On October 1st, 2017 we learned about

An emptied Mediterranean Sea enabled an increase in volcanic eruptions

Earthquakes can be bad. Earthquakes blocking off a key water source are likely worse. Earthquakes blocking water that eventually trigger volcanic eruptions would be… ridiculous? It may sound like a script to a summer blockbuster from the 1990s, but this story actually took place in the Miocene Epoch, around seven million years ago, leaving the Mediterranean Sea dry enough to walk across. The ground, and water levels, have obviously moved again since that time, but layers of earth all around the Mediterranean still tell the story the Messinian salinity crisis, when the sea was walkable and apparently lined by unusually active volcanoes.

Sediment layers under the sea

In cliffs along the Mediterranean, you can see layers of salt and gypsum crystals that were deposited thanks to evaporating seawater. It’s not surprising to see those sediment patterns in cliffs now exposed to the Sun, giving evidence to higher water levels long ago. The plot thickened in 1961, when researchers drilling under the Mediterranean Sea found the same patterns under water. For evaporation to have laid down salt and gypsum there, the only explanation was that what’s now the bottom of the sea was temporarily exposed to the Sun, although more than sunshine would have been required to dry up 965,300 square miles of water.

The loss of water was thanks to some major earthquakes near the strait of Gibraltar. As the European and African tectonic plates ground into each other, land was pushed up, blocking up the flow of water between the Atlantic ocean and the Mediterranean Sea. Without a regular supply of new water, the Mediterranean Sea was more susceptible to evaporation, drying up up enough to loose a half-mile of depth in places where water remained. The Sea started to look more like lakes, and which a new study suggests is what started to make some local mountains look more like volcanoes.

Water goes down, magma comes up

As much as we associate magma with being hot water with being cool, the big issue here was actually weight. Water is heavy enough to simply weigh down the ground, demonstrated recently by the 0.8 inches Houston, Texas was measured to have dropped under the weight of Hurricane Harvey’s rainfall. The dried Mediterranean greatly reduced the pressure on the ground below it, which allowed magma to more easily rise to the Earth’s surface. As a result of the magma’s freed movement, the rate of volcanic eruptions in the area more than doubled, with at least 13 eruptions taking place around 5.9 to 5.4 million years ago. To put it in a nutshell, blocking up the water effectively unblocked the magma.

Since the Mediterranean doesn’t currently look like Mordor, it’s easy to surmise that these changes were all reversed at some point. Another series of earthquakes reopened the strait of Gibraltar bit by bit, allowing the Atlantic to come rushing back in. Sediment layers suggest that these floods occurred more than once, although it’s unknown if that would have made for another disaster movie, or just welcome relief from the salty land and extra eruptions.

My kids asked: What about animals that got stuck out there when the water was gone and came back?

These transitions were probably difficult for most organisms. Even as water slowly dried up, the increased salinity would have giving many marine species a run for their money in whatever water remained. At least a few animals probably wandered out when the water was low, only to be isolated on newly defined islands when sea levels returned to normal. Once trapped on an island, it’s likely that some species underwent island dwarfism or gigantism thanks to the environmental pressures of living in a very different space than their ancestors did.

Source: Disappearance of Mediterranean Sea Seven Million Years Ago Triggered Widespread Volcanic Activity by David Bressan, Forbes