Study uncorks possibility that ancient water supports ancient life
Photo: J Telling
Gas bubbles from briny water emerging from the floor of a deep mine. The water’s chemical composition could feed microbes, if any are living here, 2.4 kilometers underground.
Water gushing from a deep mine in Ontario has been isolated from the surface for more than a billion years, a Canadian-United Kingdom scientific group reported today. Intriguingly, the water contains hydrogen and methane, which support bacteria and bigger organisms in the ocean depths, another location where sunlight, life’s usual source of energy, is unknown.
Several analyses indicate that the mine water has been underground for 1.5 to 2.5 billion years, more or less.
Tests for bacteria in the Ontario samples are not complete, but scientists have already found microbes trapped for millions of years in a South African gold mine.
The new study could expand the size and age of the immense bacterial realm beneath our feet, and could even help justify the search for life inside Mars, where geologically quiet regions may retain the liquid water that dominated the planet’s surface billions of years ago.
In deducing how long the water has been isolated from the surface, the researchers focused on inert gases like helium, xenon and argon, which abstain from chemical reactions.
Water sampled in the Timmins mine, in Ontario, flows due to the immense pressure from cracks and crevices in the “basement rock.”
The isotopes of an element are chemically identical but have different physical properties, such as mass. Particular isotopes can only come from a limited number of sources, and do not undergo radioactive decay.
The ultimate source of helium-4 is uranium, and measuring helium-4 can produce an age for the fluid, says project leader Chris Ballentine of the University of Manchester. “We know the concentration of uranium in these rocks, and can calculate that it would take X number of years for this level of helium-4 to build up.”
Credit: L. Li
Look but don’t drink: The water coming up from boreholes in the Ontario mine, “Looks very appetizing, it’s crystal clear, sparkling,” says Ballentine, “but the gas mixture is odd; it’s methane, hydrogen, helium rich.”
The researchers calculated that the accumulation of helium-4 would require about 1.14 billion years. Argon-40, another stable isotope, derived from potassium, would require 1.5 billion years. Those dates could be off by hundreds of millions of years in either direction.
Three xenon isotopes provided data on isolation from the surface. “Other workers have been looking at how the xenon isotope composition in the atmosphere has evolved,” says Ballentine. “A small amount of the atmosphere is dissolved in water when it is last at the surface, and when the water percolates into the ground, it takes that signature with it.”
Close-up of a tubeworm located deep in the Gulf of Mexico. Bacteria living in the tubeworms metabolize sulfide compounds, creating “chemosynthetic energy” that sustains both organisms.
The final step is to match the xenon concentration in the underground water to a time when the same concentration was present in the atmosphere; this process yielded an age of about 1.5 billion years.
Answering the “so-what?” question
The study gives a new view of how water behaves deep underground, says Ballentine, who studies fluid migration. Knowing how fluids form and move will, for example, shed light on what may happen if carbon dioxide gas is pumped underground to reduce greenhouse gas pollution.
Although the ancient water contains methane and hydrogen, which support bacteria in some locations, the “million dollar question” remains to be answered, Ballentine says. Nobody yet knows whether life is present in the water from the Ontario mine. Still, he adds, “We have found an environment that can host life, support it and nurture it for hundreds of millions, or billions of years.”
Because the ancient rock in the Ontario mine is located on the Canadian Shield, where earthquakes and volcanism are absent, “the most important implication is the extent of time that these environments can support life… without being disrupted.”
It’s almost certain that similar locations exist elsewhere, Ballentine adds. “Eventually we hope to find a spectrum of ages that would allow us to … start building a far better understanding of how life finds these pockets, evolves in them, and survives in them.”
Admittedly, that statement is premised on a big “if.” As Ballentine concedes, “We don’t know if there is there life down there, or even what it would look like.”
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
Placid, beautiful, mysterious: The Laguna del Maule caldera is all of these today. When will it wake up and reveal the molten rock that is driving one of the most active volcanoes on the planet?
Curiously, Laguna del Maule, situated along the spine of the Andes, doesn’t even look like a volcano. No towering peak, no plume of smoke or steam, no stench of sulfur. But 36 times in the past 20,000 years, volcanic vents surrounding the lake basin have created monster fields of lava — with huge deposits of volcanic glass, pumice and ash.
Once, almost a million years ago, this volcano field had an eruption that, if repeated, could change history by affecting air travel, agriculture and climate. Tantalizing scraps of lava indicate enormous eruptions 1.5 million and 336,000 years ago.
This peninsula, formed during a lava flow 24,000 years ago, is near the center of uplift today — and therefore likely a marker for a growing chamber of magma.
It’s a maxim of geology: What happened before can happen again.
The volcanic field is 20 kilometers in diameter, and the recent surge in attention is largely due to a widespread, 1.5 meter rise since 2007. “That’s phenomenal,” says Brad Singer, a professor of geoscience at the University of Wisconsin-Madison, who began studying this part of the Andes 20 years ago. “There is no other volcano in the world that is going up at this rate.”
The Why Files
Brad Singer explains the role of rock samples in understanding the volcanoes at Laguna del Maule.
Other causes for concern include swarms of earthquakes, horizontal spreading, spreading faults, and new detections of carbon dioxide gas that likely signal the enlargement of the underground magma pool that powers the volcano.
Eruptions can be ranked by estimating the volume of volcanic ash (mainly tiny shards of glass) they release. In 1980, Mt. St. Helens released about one cubic kilometer. In 1991, Pinatubo in the Philippines sent more than 10 cubic kilometers; its ash and sulfur gas injected into the upper atmosphere cooled the planet for two years.
About 950,000 years ago, an eruption at Laguna del Maule spewed dozens of cubic kilometers — perhaps more than 100. The eruption blanketed Argentina, downwind, with ash.
Based on data from Geological Society of London, 2005 and Gunder and Mahood, 1988. Graphs by The Why Files
The bigger the eruption, the less common it is. Laguna del Maule could go back to sleep, or (rollover) enter the history books as the largest eruption in recorded history.
Past is prologue
A 100 cubic-kilometer eruption could cause global cooling, and intense damage to agriculture could affect the entire globe.
Because the only people around Laguna del Maule are the horsemen who drive cattle in the summer, the immediate human impacts will be limited — unless giant flows of hot rock or debris reach Chilean cities. But dense ash-fall during the growing season could devastate agriculture in Argentina, to the east.
Just 50 kilometers north of Laguna del Maule, a similar volcanic field, called Calabozos, has had three super-eruptions in the past million years, spewing about 1,000 cubic kilometers of ash in total.
Those eruptions rank among the largest in a million years.
The Why Files
Laguna del Maule, a massive volcanic complex in Chile, could change the planet, with an eruption like three giants at nearby Calabozos. Maule could be returning to life. How dangerous is that?
The immediate cause of concern at Laguna del Maule comes from radar satellites and the global positioning system, which show that 1.5-meter rise in six years. The accelerating uplift is almost certainly due to new magma entering a pool located five kilometers underground.
Volcanoes are fed by molten rock, or magma, located deep underground. A weak spot in the crust allows magma to reach the surface, where the rocky products are called lava. In places like Laguna del Maule, silica-rich lava holds vast amounts of water. When pressure drops, this water flashes to steam; the rapid expansion of volume drives explosive eruptions.
In 2013, with support from the National Science Foundation, UW-Madison geoscientists began a field campaign to gather more basic data on Laguna del Maule.
“Our aim is to try to figure out if magma is actively intruding in the crust below the volcanic field,” says Singer, who worked at the site with U.S. Geological Survey expert Wes Hildreth, who started the first systematic mapping of the area in the 1980s. “We hypothesize that this is what is inflating the crust,” Singer says. “It’s like a balloon blowing up the surface.”
History, says Singer, is usually a good guide to the future. Laguna del Maule has “had at least three million years of pretty constant igneous [molten-rock] activity, and about every half million years it looks like a fairly substantial, caldera-forming eruption. Are we overdue for another?”
A caldera is a ring-shaped structure formed when by collapse when a giant pool of magma is vented to the surface.
Stupendous super-eruptions
Humans have seen the aftermath of super-eruptions, but never the eruption itself, which may disgorge a million tons of rock every second. If the past is a reliable guide, super-eruptions can change the planet.
The caldera at Lake Toba, in Sumatra, Indonesia, formed during a stupendous super-eruption about 70,000 years ago. In its last eruption (so far!) the volcano released about 2,800 cubic kilometers of lava and ash!
The effects of “Rare but extremely large explosive supereruptions …will be felt globally or at least by a whole hemisphere,” wrote two scientists in 20081. The most widespread effects are likely to derive from the volcanic gases released, particularly sulfur gases that are converted into sulfuric acid aerosols in the stratosphere. These will remain for several years, promoting changes in atmospheric circulation and causing surface temperatures to fall dramatically in many regions, bringing about temporary reductions in light levels and producing severe and unseasonable weather (‘volcanic winter’). Major disruptions to global societal infrastructure can be expected for periods of months to years.”
The questions we ask
“Volcano” and “prediction” are not words that geologists like to join together, but the essential goal at Laguna del Maule is to understand the situation well enough to answer a simple question: How likely is an eruption that would be large enough to affect the region or the planet?
How much do we need to worry?
Singer hopes that the 2013 exploration of Laguna del Maule will soon be augmented with a wider variety of analytic techniques:
Dating techniques can tell when magma cooled at the surface, revealing the “pulse” of eruptions.
Mineral analysis can assess the physical conditions before previous eruptions, and suggest how changes in the magma trigger eruptions.
Seismology uses earthquakes and explosions to define the shape of underground structures.
Gas measurements offer clues about the type and volume of magma under the volcanic field.
Electrical and magnetic measurements outline the shape of a magma chamber.
Gravity meters can detect changes in the volume of magma at depth.
Eyeballs, a venerable tool of geology, can see faults, uplift and lava from past eruptions.
These techniques gain precision if their data are merged, Singer says. Many methods “can give a fuzzy picture of what’s down there, but the more techniques you can bring to bear, the more you can tighten up the boundaries between different materials” and so get a better picture of the magma and its potential routes to the surface.
Brad Singer (left) advises UW-Madison graduate students Nathan Andersen and Erin Birsic, as they hunt for rocks of a certain age for Birsic’s master’s thesis. She is focusing on remnants of a massive eruption from 950,000 years ago, but after millennia of erosion those rocks are scarce.
Need a date?
If you need a date, Singer is a good guy to know, at least if you want to date rocks. A specialist in geochronology, Singer uses sensitive instruments to squeeze out a date of formation for igneous rock, meaning when the rock solidified from cooling magma.
The overall goal at Maule is to tease out the timing of the many lava flows in the basin.
One dating technique relies on the radioactive decay of potassium into the gas argon, which follows a schedule set by the half-life of the isotope potassium-40.
Magma is hot, and any argon present will diffuse into the crust, but argon is trapped after magma cools into lava at earth’s surface. “Once it cools past a certain point, then argon stops diffusing, allowing argon produced from radioactive decay to build up,” says Nathan Andersen, a Ph.D. student in geoscience at Wisconsin who is dating recent lava flows at Maule.
Potassium-40 decays into argon-40, and so counting each isotope becomes the foundation for calculating the date of cooling.
However, potassium decays slowly, and this system has yet to date recent flows at Laguna del Maule, which are apparently younger than 2,000 years.
The eyeball on the highball
High-tech is eye-catching, but once you know what you are looking for, eyesight offers insight. Look at the large granite intrusions underneath Tatara San Pedro, a nearby volcano. The granite is apparently the remains of a magma chamber which cooled about 6 million years ago.
“It looks like a frozen magma body that is analogous to the magma body we think is active beneath Laguna del Maule today,” Singer says. Similar bodies of frozen magma have risen over 80 million years in California’s Sierra Nevadas. “But here, it’s now 2,500 meters above sea level. That’s 7,500 meters of uplift in 6 million years!”
The express elevator that is raising Laguna del Maule can be seen with the naked eye. White streaks on certain parts of the shoreline contain diatoms and ash that were deposited in the lake. “These are a sign that the uplift has been going on for many centuries,” Singer says.
Laguna del Maule was much larger 19,000 years ago; then the lake level dropped after a lava dam broke. Black arrows show traces of the old shoreline; blue arrows show a landslide that occurred since the sudden drop in lake level.
The lake bench, 200 meters above the existing lake, shows an old shoreline that, when formed, was as horizontal as the lake itself. Singer suspects that the profile of the bench carries a long-term record of uplift.
Faults, which show how adjacent sections of rock have moved against each other, are another eye-catcher. Last year, the Wisconsin scientists found new evidence of horizontal spreading and faults; these structures show earth movement, and could facilitate the rise of magma and an eruption.
The Laguna del Maule landscape is steadily changing. The white scrap of cooled magma (foreground) is the eroded remains of a massive lava flow. The rock originated as a pyroclastic flow; a fast-moving, red-hot material that cooled after being deposited, probably about 19,000 years ago.
If you know what you are looking at, small outcrops can play a large role in understanding the geologic history at Laguna del Maule. Analysis of the chemistry, minerals and texture of rocks can show that remote outcrops are remnants from a single eruption, or a single magma body. “When you start to see rhyolite on one side of the lake,” Singer adds, “and identical rhyolite on the other side, and you try to imagine how big the system must have been to produce both of those eruptions, that really grabs your attention.”
(Rhyolite, an uncommon type of magma that is rich in water and silica, and resistant to flow, is the most explosive and dangerous magma on the planet.)
Finding chemically similar lava over such a large area indicates that a large eruption is possible in the future.
Measuring the ground shaking
When the earth moves, the resulting vibrations convey clues about the planet’s internal structure. Both earthquakes and deliberate explosions can produce a “CAT scan of the crust,” based on how waves are transmitted, reflected, absorbed or converted into different waves, says Clifford Thurber, a seismologist at UW-Madison.
Earthquakes radiate P and S waves:
P, or “primary,” waves resemble sound waves, with zones of compression and decompression.
S, or “secondary,” waves, are a bit slower, and travel rather like a slithering snake.
In the first months of this year, seismographs at Laguna del Maule were “detecting repeated swarms of earthquakes, clusters that happen close together in time and space,” Thurber says. “Those are hallmarks of magmatically active volcanic systems, but they do not prove anything. On the other hand, if it were seismically silent, one would have to wonder if anything is going on.”
This building in Talca, Chile, was destroyed by the magnitude 8.8 Maule earthquake in 2010. This, the sixth-largest quake ever measured, killed 525 people.
After a swarm of earthquakes in March, 2013, scientists at the Chile’s Southern Andes volcano observatory issued a yellow alert, indicating that an eruption was possible in weeks or months.
Stronger and longer earthquake swarms and tremors are danger signs, Thurber says. “If we get sustained tremor, a low-level shaking that continues for hours to days, then we would get nervous. If we start to get very large earthquakes, 6 magnitude, it’s time to go.”
Thurber is introducing state-of-the-art computer analysis of seismic waves that will pinpoint arrival times more precisely. With improved earthquake locations, “We can do a better job of clarifying the structures that produce the earthquake,” Thurber says.
With a seismic expert on the line, we had to ask why the giant 2010 Maule earthquake did not trigger an eruption at nearby Laguna del Maule, just a few hundred kilometers the east of the epicenter. “It’s odd,” says Thurber. “This happens around the world. Sometimes a large earthquake triggers activity, and sometimes it does not. The volcano has to be ready.”
The Why Files
Glyn Williams-Jones explains the significance of carbon dioxide measurements at Laguna del Maule.
Gas attack!
Volcanoes can release staggering amounts of gas: Mt. Pinatubo coughed up an estimated 20 million tons of sulfur dioxide.
Carbon dioxide, a hallmark of basalt, is the big concern at Laguna del Maule, and
despite difficulties with two brand-new carbon dioxide meters, Glyn Williams-Jones, a volcanologist at Simon Fraser University in British Columbia, did find some elevated levels along the lakeshore in 2013.
“That means there is basalt entering the magma chamber from below,” says Williams-Jones.
Newly arrived, extremely hot basalt could interact with the existing rhyolite magma and boost the odds of eruption.
The Why Files
Helene Le Mevel, a graduate student, adjusts a meter that measures the local gravity field with astonishing precision. If significant amounts of magma are rising underground, gravity should be weaker in next year’s measurements — if the measurements are precise and accounts for the ongoing uplift of the area.
Electrical currents
To get a better sense of what’s happening under ground, geophysicists can measure electrical currents and magnetic fields inside Earth. “The surface is bathed by electromagnetic radiation from the sun, and there is an electrical response at depth,” says Singer.
The technique, called magnetotellurics, is used in geothermal energy exploration, and an energy company has already used it to find a shallow steam field just west of the caldera that could power a geothermal electric generator.
Magnetotellurics has already revealed that the crust around Laguna del Maule is about 40 kilometers thick, and that the magma body is about 5 kilometers below ground, Singer says. In the future, the technique could help define the size and location of melted crust near the magma chamber.
Gravely measuring gravity
Accurate measurements of gravity are another telltale about changes in the hot, molten magma. Because matter expands as it warms, magma is 10 percent less dense than surrounding rock, explains Basil Tikoff, a UW-Madison specialist in large-scale structure of the Earth, such as faults, old mountain belts and tectonic plates.
Gravity “does not have the resolution of other techniques, and it requires an enormous amount of fieldwork,” Tikoff says. “It’s a kind of geophysics that very few geophysicists do now.”
The Why Files
Basil Tikoff of UW-Madison explains the role of the gravity meter.
In March, Tikoff, graduate student Helene Le Mevel, and Williams-Jones installed 38 gravity stations on two lines crossing the center of uplift. The gravimeters are built around an ultra-precise spring that allows a suspended weight to respond to gravity. Although the meters are more than one-h century old, they are accurate to one part in 100 million. “If there is an earthquake, we have to turn the gravimeter off and wait,” says Tikoff. “If the land is going up and down, the gravimeter can see that, even if we can’t feel it.”
The pull of gravity decreases as the instrument gets farther from the center of the Earth. “This instrument is so sensitive that if we went up a few stairs, you could tell,” Tikoff says. Therefore, Laguna del Maule’s pervasive uplift must be mathematically removed from subsequent measurements.
Baseline measurements taken in March and April will serve as reference points for subsequent surveys early in 2014. Located at the crest of the Andes, Laguna del Maule will be impassable until then due to its astonishing snowfall.
What comes next?
Laguna del Maule is a contradiction. To people who would be affected by a large eruption (which could include all of humanity in a super-eruption) it’s a threat.
But to geologists, it’s an opportunity to see how Earth is changing, and that is what draws Singer back. “The processes of deep Earth history are abstract,” Singer says. “I am more attracted to things that happen to the planet on a rapid time scale, such as glaciers and volcanoes. These take place on a human time scale.”
March, 2013, The Why Files
Gravimeters must be protected from vibration due to wind. Graduate student Tor Stetson-Lee blocks wind as Basil Tikoff measures gravity on the east shore of Laguna del Maule. That flying-saucer-on-a-stick is a GPS receiver able to measure altitude in millimeters.
The explanation for the new activity is pretty clear, Singer says. “There is no reason other than new magma to explain uplift of that size.”
The rapid uplift, combined with swarms of small earthquakes, apparent releases of carbon dioxide, and spreading of faults cannot go on forever. If they continue, the magma’s upward pressure will eventually exceed Earth’s ability to contain it.
Then Laguna del Maule erupts.
Until then, geoscientists see a chance to observe in real-time processes whose results can be seen all over the planet, and there is lots to be learned before the eruption, says Singer, who normally looks, forensic-style, after the eruption. “I try to reconstruct the history of magmas that feed the volcano, and how the processes inside the magma affect the way the volcano erupts, whether it’s explosive or passive. I try to stay away from them when they are erupting.”
Volcanoes usually emit a sequence of warnings, including a critical change in seismic signals, but nobody knows if Laguna del Maule will break the mold or follow it, adds Thurber, the seismologist. “We don’t have perspective. Studies that have been done on systems like this have exclusively been done after they have blown their top.”
Volcanoes are inherently unpredictable, especially the bizarre giants like Laguna del Maule, Thurber says. “We have no idea what the timeframe is to go from the rapid inflation we see now to an eruption. It could stop inflating and say ‘I’m done for now.’ It’s completely unpredictable; it could erupt tomorrow, next week, next year, next decade, next century. We don’t know for sure it is going to blow, but it sure as heck looks like it. If it erupts, the fact that a study had been done beforehand would be phenomenal, and unique in the world.”
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
Bibliography
Consequences of Explosive Supereruptions, Stephen Self and Stephen Blake, Elements, Vol. 4, 41–46 ↩
Supervolcanoes and their explosive supereruptions, Calvin F. Miller and David A. Wark, Elements, Vol. 4, pp 11–16. ↩
On Feb. 28, 2013, the earth opened up in Seffner, Florida, and Jeffrey Bush fell to his death. Local authorities decided they could not safely recover the body: excavating the rock and sand would cause more collapse and more danger.
Jeremy Bush, who tried to save his brother, Jeff, says his parents are ‘going through hell’ after Jeff died in a Florida sinkhole Feb. 28.
Then, on March 12, an Illinois golfer fell through a sinkhole — possibly associated with an abandoned mine — on the 14th hole. Mark Mihal, 43, survived an 18-foot fall with just a sore shoulder, after his golfing companions fished him out with a rope.
This house suffered severe damage in Brooksville, Fla., 50 miles north of Seffner, site of the recent tragedy.
The incidents are graphic examples of the dangers of taking geology for granted. Earth is not always as solid as a rock.
In large parts of Florida and other states, a soluble subsurface geology called karst is conducive to sinkholes. Karst occurs in rock dominated by gypsum, limestone or salt — which can dissolve, leaving underground streams and cavities.
The U.S. Geological Survey says about 20 percent of the United States overlies karst terrain; the worst sinkhole damage occurs in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania.
Classically, sinkholes occur in locations where water, unable to flow laterally, percolates through soluble rock, creating caverns and cavities. Often, the surface will gradually subside, causing a cover-subsidence sinkhole. And as we’ll see, other forms of collapse are popularly called sinkholes as well.
Gradual movement of soil grains into cavities in karst can result in a widespread form of sinkhole that is damaging, but not especially dangerous.
More rarely and dramatically, when the roof span becomes too large, the outcome is a “cavity collapse” sinkhole. That was apparently the fatal flaw in Seffner, Fla.
The undetectable underground changes can take centuries, until the earth gives way with a sudden, dangerous collapse.
Subsidence can also occur
Above mines and underground streams
In organic soils that shrink when they decompose
After routine activities like pumping groundwater up for drinking and irrigation, which removes water from an aquifer and reduces the volume of sand and gravel, causing subsidence
In cold winters in the strawberry fields east of Tampa, Fla., farmers pump groundwater so they can spray their crops to prevent freezing. “In 2010, this opened about 140 sinkholes,” says Mark Stewart, professor of geology at the University of South Florida. “Most of them did not damage homes, but several did, and there was some damage to an interstate highway.”
Cover-collapse sinkholes dominate in the blue and purple regions.
Because wells are a known trigger for sinkholes, many subdivisions in the sinkhole-prone North Tampa area prohibit private wells, Stewart says. “You can’t have a well for irrigation or water supply. You have to be on city water.”
At least one man was killed after a three-storey building fell into this 200-foot-deep hole after Tropical storm Agatha dumped more than three feet of rain on Guatemala. Rollover to see a street-level view.
If removing water can cause collapses, so can adding water through leaking water pipes, sewers and storms. Storm runoff was blamed for a dramatic hole-in-the-ground that formed in Guatemala City, Guatemala, in 2010. The city is built on a volcanic ash plateau, and groundwater, sewer systems and storm drains all feed the fragile ash. “The result is erosion of the material, which creates cavities that can collapse,” says Stewart. “It can be really catastrophic.”
In New Orleans and other river deltas, subsidence occurs as organic material in soil decomposes and new sediment, which would sustain ground level, is blocked behind levees. Parts of the Sacramento-San Joaquin river delta in California have fallen to more than 15 feet below sea level.
Sinkholes can result when industrial and water-storage ponds get so heavy that they trigger a collapse.
Pennsylvania, riddled with expired coal mines, has major problems with subsidence.
Minding mining
And then there is mining, which is a major cause of subsidence in Pennsylvania, West Virginia and Kentucky. Those states have about 60 percent of U.S. abandoned coal mines; overall, the nation has about 14,000 active mines, and up to 500,000 abandoned mines of all sorts.
A collapse at the Retsof mine in Upstate New York had broad repercussions for the economy, landscape and groundwater.
In 1994, an earthquake collapsed a 500-foot square chunk of roof rock above a huge salt mine south of Rochester, N.Y., and water began flooding in. Since the Retsof mine opened in 1885, it had grown into the world’s second-largest salt mine, covering 10 square miles.
Within 21 months, the mine was inundated and closed. Water levels dropped in wells as far as 10 miles away, and two sinkholes formed, each about 50 by 200 feet. Further subsidence is expected as groundwater dissolves more salt; eventually, as the mine roof continues its slow-motion collapse, the ground above the mine is expected to fall eight or nine feet.
A telltale of subsidence. Don’t buy this house ’til you find out what caused that nasty crack!
Finding that sinking feeling
Sinkholes can be surprising, but they don’t appear at random. In sinkhole-prone states, state geological survey maps should provide at least a general guide to risk; the USGS also has a national mapping facility.
Although a cover-collapse sinkhole may come without warning, experts say people in karst terrain should look for these signs of subsidence:
Cracks in the walls and foundation
Doors and windows that refuse to close
Settling around the foundation
Recognizing safe building sites in areas prone to sinkholes entails a multipronged approach, writes sinkhole expert Francisco Gutiérrez, professor of geology at the University of Zaragoza, Spain.
Identification techniques include field surveys and geomorphological mapping combined with accounts from local people and historical sources. Detailed sinkhole maps can be constructed from sequential historical maps, recent topographical maps, and digital elevation models complemented with building-damage surveying, remote sensing, and high-resolution geodetic [Earth-measurement] surveys. On a more detailed level, information from exposed paleosubsidence features (paleokarst), speleological [cave] explorations, geophysical investigations, trenching, dating techniques, and boreholes may help in investigating dissolution and subsidence features. Information on the hydrogeological pathways including caves, springs and swallow holes [where streams disappear belowground] are particularly important … .1
This karst landscape shows how water carves conduits and cavities in limestone and other soluble rock. The river through the village of Minerve in southern France disappears into a swallow hole in the karst below town!
Yet as the recent Florida case shows, cover-collapse sinkholes usually come out of the blue. You might think that a state laced with sinkholes would want to zone development away from danger, but the Florida Board of Realtors “is not interested in any kind of hazard zoning,” Stewart says. “To get a mortgage, you must have homeowner’s insurance, and then it would be extraordinarily difficult to get insurance, so banks would be very hesitant to give mortgages, and that would greatly affect property values” in sinkhole areas. Rather than blacklisting areas likely to subside or collapse, the trend is to “leave the risk to the homeowner.”
Better take out some insurance
The Florida insurance industry, buffeted by sinkhole claims, has pushed through a law requiring cases to be settled by arbitration, rather in court, Stewart says. “There was a substantial loss to the insurance industry, so the legislation was changed.”
This cover-collapse sinkhole occurred in limestone near Frederick, Maryland. Many sinkholes occur along highways where rainwater runoff concentrates in storm drains and ditches and erodes the subsurface. That storm sewer pipe may have played a role in creating the sinkhole.
Homeowner’s insurance in Florida does cover sinkholes, he says, but not other causes of subsidence, which can cause slow-mo damage. Insurance companies “typically call in a geotechnical firm to do an investigation. In many, many cases, it’s not due to a sinkhole, so the homeowner hires their own geotechnical firm, which says it is, and the issue goes to arbitration.”
One source of data, ground penetrating radar, which reflects off different layers in the subsurface, “can be interpreted over a broad range by experts,” says Stewart. “The level of professionalism among people in the industry has not been at its highest level. Until recently there was a lot of money to be made by lawyers, geotechnical firms and the insurance industry.”
In 2010 alone, there were more than 6,600 sinkhole claims in Florida, Stewart says. “It’s not possible to estimate how many were legitimate. There are geotechnical experts on both sides, so there is no final determination whether it was a sinkhole.”
In a sense, sinkholes, like lightning are frightening natural phenomena that seem to strike from nowhere. “A hole opened under the bedroom and the man went down and was buried while sleeping,” says Stewart. “The Earth isn’t supposed to open up under you. It’s like shark attacks; they get press even though they are extraordinarily rare. Because of the emotional attachment, people see too much risk where there is in reality low risk.”
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
Bibliography
Identification, prediction, and mitigation of sinkhole hazards in evaporite karst areas, F. Gutiérrez et al, Environ Geol (2008) 53:1007–1022 ↩
Fact: The surface of Mars shows massive erosion and huge fields of sand dunes.
Problem: Mars hasn’t had liquid water for more than a billion years. High winds are rare and its atmosphere is thin. Is the erosion due to ancient water or modern wind?
Solution: The sand dunes are blowing in the wind, moving much like dunes on Earth.
The Nili Patera dune field on Mars, where the wind blows from the right. Red box at upper right locates this area; lower inset shows a close-up of a dune’s rippled surface.
NASA/Mars Reconnaissance Orbiter/Nathan Bridges
In a study posted online May 9, Nathan Bridges and colleagues analyzed data from an eye-in-the-sky called Mars Reconnaissance Orbiter. Using a high-resolution telescope, the researchers measured the movement of sand dunes over a 105-day span.
The fine-grained images showed that the dunes are indisputably on the move, says Bridges, a senior scientist at the Applied Physics Laboratory at Johns Hopkins University. “Even though Mars has a very thin atmosphere and high-speed winds are rare, the dunes are moving.”
Technicians assemble and test NASA’s Mars Reconnaissance Orbiter spacecraft bus in a cleanroom.
The research group saw movement both in entire dunes, and in the ripples on their surface. Across one meter of dune front, they calculated an annual sand movement totaling about 2.3 cubic meters. “If you had a children’s sandbox, that would fill it with sand in a year,” Bridges says.
On Mars, as on Earth
And that, he adds, is within the range of movement seen in some Earthly dune fields. “We are not making the case that Mars has the fastest dunes, but they do move like some on Earth. Mars is an active planet, maybe not as active as Earth, but we are seeing significant movement.”
McKelvey Valley is one of Antarctica’s dry valleys. Although most of Antarctica is covered with up to 5 kilometers of ice, these mountain valleys have been mostly free of ice and snow for 8 million years. Nearby Victoria Valley had sand movement that was comparable to what was just measured on Mars.
How much wind is needed to move sand when the atmosphere is less than one percent as dense as Earth’s? The grains would start moving in a wind of about 20 to 30 meters per second (40 to 50 miles per hour, measured at a height of 1 meter), Bridges says. “That is about 10 times what you need on Earth, due to the atmospheric density difference.”
Such winds do blow — rarely — on Mars, but once the sand starts moving, it’s easier to keep it rolling, he says. “Recent research by my colleagues has found … a lower-speed wind can sustain the movement.” Under the reduced gravity of Mars, a grain stays aloft longer, giving the wind more time to accelerate it. When the high-speed grain hits the sand bed, a high-energy collision impels more sand grains into motion.
Mars: A moving planet
At any rate, the discovery proves that wind needs no help from water in moving dunes, Bridges says. “We have seen dunes in images since the 1970s, but there was a question, were they currently active, moving? Mars has a very thin atmosphere and it would need high-speed winds to move sand, and those are very rare. So it’s been an open question, how much sand is moving now, and was more moving in the past?”
On Earth, water is highly erosive, but Mars has no liquid water, “so one agent of erosion on Earth is lacking,” says Bridges. “There is a lot of evidence for erosion — craters that appear to be filled in with dirt, and the primary mechanism is wind.”
An enhanced-color image of dunes and sand ripples of various shapes and sizes in Noachis Terra Region of Mars. The area measures about 1 kilometer across.
And lasting sandblasting
Wind does not just move sand — it also creates sand, Bridges says. His group calculated that the natural Martian sandblaster sand would erode 1 to 50 microns off rock per year, about the same rate as in Victoria Valley.
That sandblasting would provide a source of the sand that litters so much of the red planet, Bridges says. “Erosion is occurring today, so wherever you have sand, and moderate winds, you are likely to get significant amount of erosion from rocks.” That could then create silt or more sand.
When we see all these eroded terrains, “you don’t have to evoke any past climate to explain this,” he says. “It’s a current process, and it was likely occurring for billions of years.”
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
Bibliography
Earth-like sand fluxes on Mars, Nathan Bridges et al, Nature, published online ahead of print 9 May 2012, doi:10.1038/nature11022 ↩
Volcanoes are big movers and shakers in the business of continually redesigning the Earth’s landscape. With no concern for nearby people or ecosystems, volcanoes release toxic gases, climate-altering ash, lava and rock. How does this work? Are scientists getting better at predicting volcanic eruptions? How do areas recover after destruction?
How does a volcano work? Where does the energy come from? Why do some volcanoes explode while others ooze lava?
What instruments do scientists use to predict volcanic eruptions? What do these instruments record? What do they tell us about the volcanic/geological activity going on below the surface?
How do landscapes recover after being scoured by a volcanic blast? Discuss the role of burrowing animals, fruit-eating birds, and different types of seed and roots.
Lesson Plans/Activities
What’s your favorite volcano? How Volcanoes Work has in-depth information on volcano types and activity. Recommended for grades 7-12.
Predict an eruption! In this fun, interactive online activity, students learn how to use instruments and interpret data that volcanists use to predict volcanic eruptions, and then apply this knowledge to a fictitious volcano scenario. Recommended for grades 7-10.
Super-dangerous super-volcanoes: Predictable at last?
Running short of worries? Then ponder the super-volcanoes — earth-bombs that can vomit 10 or 100 or 1,000 cubic kilometers of molten rock. Super-volcanoes can change history by creating rivers of red-hot ash moving at highway speed, spreading dust across hundreds of kilometers and spewing vapors that block the sun, destroy crops and start famines.
This ring-shaped structure is the caldera at Santorini, in the Mediterranean Sea. In terms of what it threw up, the eruption at Santorini about 3,500 years ago was one of the top four in the past 5,000 years.
A volcano may go dormant for thousands of years after such a huge eruption, so they may be even harder to predict than smaller ones — which are also unpredictable at this point…
But this week, Nature published a new analysis of Santorini, a Mediterranean monster, that shows the movement of molten rock that preceded the eruption.
Santorini’s sudden release of 40 to 60 cubic kilometers of rock and ash was followed by a giant collapse that left a characteristic ring of hills called a caldera. Thousands may have died in the eruption, which laid down a 60-meter layer of ash and rock.
Eruptions of this general size happen about every 300 years, says Timothy Druitt, a volcanologist at the Université Blaise Pascal in France, who lead the current study. The most recent was in 1815 at Tambora, in Indonesia.
Druitt’s new analysis of crystals within the frozen magma offers a rough schedule for the entry of molten magma into a holding tank — the magma chamber — below the volcano, which is a precursor to eruption.
Caldera-forming eruptions rival earthquakes and tsunamis as the deadliest natural disasters. “People who work in the field know these volcanoes are not rare, even on a human time scale,” says Druitt, but “we have never been able to monitor one of these big eruptions during the long buildup phase, so we are not really sure how that happens.”
The crystal analysis detects microscopic changes in chemical composition, offering a unique, after-the-fact picture of the gestation of eruption.
This mantle of rocky debris was left by the last big eruption at Santorini, about 3,500 years ago.
In the crystals
As crystals grow in the cooling magma, atoms of trace elements diffuse within them, and both growth and diffusion are affected by conditions within the hot magma, says Druitt. “These crystals grow progressively, and as they do, their chemical composition changes according to the composition of the magma around them, and the temperature and amount of water in the magma.”
Electron-microscope image of a plagioclase feldspar crystal from Santorini pumice shows the original crystal in light gray, and the growing portions as darker gray. The red line shows where atomic concentrations were measured.
The crystals revealed that a big gob of magma — perhaps 10 percent of the magma chamber’s total contents — entered in the decades before the eruption. “Looking at the crystals in this magma, we were able to reconstruct very crudely events taking place in the last few decades prior to the eruption,” Druitt says.
That final addition probably made the magma chamber unstable, leading to the eruption, Druitt explains.
If such a late, large magma movement proves typical of super-volcanoes, that could contribute to a distant early warning system for mega-eruptions, based on more conventional methods, such as seismic monitoring.
Distant early warning
But the findings also carried a caution, Druitt says, since Santorini was apparently dormant for about 18,000 years before the last apoplectic outburst. “That is a slightly alarming result. There are lot of these big caldera systems, but most are in a stage of repose.”
The upshot is more proof that a dormant volcano can still be a dangerous one, he adds. “We can imagine that a big caldera in a remote region of the world, such as the Andes, which is not monitored very well, could reawaken pretty quickly on a human time scale.”
The super-volcano at Yellowstone is fed by magma — molten rock — originating deep in the Earth.
As the magma chamber fills, pressure increases until the volcano explodes. When the rock above the magma chamber collapse, a huge crater results. These calderas only form at large volcanoes.
The crystal method gives after-the-fact data on an eruption. Current attempts to anticipate eruptions rely on data about earth shaking, deformation of the crust, and release of gases.
“It’s a very timely topic, and solid science in terms of the measurements and observations,” says Bradley Singer, a volcanologist and professor of geoscience at University of Wisconsin-Madison. “They admit that there are issues about the time scales,” largely because the diffusion of strontium and titanium is imperfectly understood in the hot magma.
The study’s title, however, specifies that the final growth of the magma chamber occurs on “Decadal to monthly timescales,” Singer notes. “It could be centuries or even longer, which implies that we’d have a longer time prior to the eruption” to worry about the effects of the rising magma.
Singer concurs on the importance of understanding the relationship of magma flows, instability and eruption, and says the crystal analysis is gaining traction in volcanology.
That’s just as well, since giant caldera-forming volcanoes may be frighteningly common. The one at Yellowstone, for example, released 1,000 cubic kilometers of rock 640,000 years ago. Wouldn’t you want to know if something like that was building on your continent?
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
Bibliography
Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano, T. H. Druitt et al, Nature, 2 Feb. 2012. ↩
Volcanology: Greek inflation circa 1600 BC, News and Views, Jon Blundy & Alison Rust, Nature, 2 Feb. 2012. ↩
Interested in waterfront property in Southern California? A new study of a continental schism running east of Los Angeles offers a clear “buy” signal for the long-term investor: The North American continent is splitting apart along a rift, and if you got the patience, we have the real-estate-appreciation potential!
In just a few million years, as the North American continent sunders in a weak zone called the Salton Trough, the Gulf of California will stretch further north.
On our unstable Earth, not even the continents are rock solid. Instead, they shift around like blocks of sea ice that join, fissure and separate once again — over millions of years.
Geologists know the process is occurring in the Southern California desert, and we’ve just read a sophisticated analysis that finds an ominous thinning of the strong crustal layer in the Salton Trough.
Ominous, that is, unless you are planning a waterfront resort here, with a grand opening in, say, 2,002,011.
The study helps to fill a gap in our understanding of the earth, says first author Vedran Lekic, a National Science Foundation post-doctoral fellow at Brown University. “The main question is, how do continents come to break apart? This process is really fundamental to shaping how the Earth looks; if not for rifting, once Pangaea formed, it would never have broken apart and we would have only one continent.”
Pangaea is a giant agglomeration of continents that broke up about 150 million years ago, creating our current collection of continents.
Revised from original graphics courtesy Vedran Lekic. Top image: graphics overlay of GoogleEarth image.
The surface depression (upper black line) echoes the thinning just found in the lithosphere (located between the black and white squares). Map shows location of this cross section.
Scoping out the Earth
The lithosphere, Earth’s crust and the rigid rock beneath it, essentially floats on the asthenosphere, the soft and hot outer layer of the mantle that is located tens of kilometers belowground.
As a continental rift grows, one would expect to find a thinned lithosphere at the Salton Trough. But Lekic says the actual thinning was more dramatic than expected — as much as a 50 percent reduction compared to adjacent areas.
The new research relied on data from hundreds of seismometers in the National Science Foundation’s EarthScope network, and in Caltech’s Southern California Seismic Network.
By studying earthquake waves passing through Earth, Lekic and colleagues measured the thickness of the lithosphere by locating its lower border. They knew that one type of wave converts to a faster wave type as it passes up from the asthenosphere into the lithosphere, so the conversion could be used to mark the base of the lithosphere.
It turned out that the lithosphere measured about 40 kilometers thick beneath the Salton Trough, compared to 60 to 80 kilometers on nearby areas. That thinning translates into a weakening that will eventually allow open water into the Trough, and myriad real-estate opportunities along the new shoreline.
Previous efforts to estimate the lithosphere’s depth have relied mainly on surface data, says Lekic, and that limited our knowledge of how the continental splitsville takes place. From relying on “surface observations of faults, topography, heat flow, and some studies of the crustal structure, we have not been able to image the detailed topography of the base of the tectonic plate, as it looks during rifting.”
Rift terrific
Although the study relied on the interest in Southern California seismology that is a response to extreme seismic activity, the finding says little about earthquake probabilities.
The elongated lakes and great valleys in East Africa, caused by the separation of tectonic plates, are the classic example of continental rifting.
But earthquakes are not the only tectonic game in town, says Eugene Humphreys, a professor of geophysics at the University of Oregon. “While most people know southern California is being sheared by the San Andreas and related faults, most people are not aware that the region also is being pulled apart as the Pacific plate also moves slowly away from North America. These researchers have imaged the deep structure of the plate where it is being torn apart by this process, and contrary to what many have thought, the tears go through the entire plate right where the surface expression of this rifting is seen. It’s exciting work.”
The study provides insight into deep structure and processes of fluid migration up into the plate, says Humphreys. “These lower-plate interfaces were not expected to exist at all, and the scientific community is excited but struggling to determine what could create relatively sharp interfaces.”
Although Earth warms with depth, that is unlikely to explain the weakness, Humphreys says, “so the search for other causes is on. By associating the position and shape of these interfaces with a specific deformation history, this study provides important information on the origin of these interfaces.”
Lekic, who worked with co-author Karen Fischer of Brown, on the study, says that “Even at great depth, we see the same stretching and deformation that we see near the surface. At the bottom of the lithosphere, there is this persistent weakness, in a zone that runs more or less vertically, and that’s surprising.”
But as scientists wrestle with the geological goulash that is Southern California, we suggest you send a down payment to Rift ‘n Grift Realty on the ocean-front lot of your dreams – and wait a few million years!
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
We approach the Cave of the Mounds, a landmark (so to speak) in Southwest Wisconsin, along a walkway painted with fossils and markings that start at the Ordovician era (450 million years ago), when the limestone beneath our feet was deposited as a rain of sea shells on an ocean floor. Finally, at the cave’s entry, the asphalt calendar enters the last million years, when the cave started to be excavated by flows of acidic water.
Theatrical lighting brings the pitch-black to life! That gooey stuff in the center and left is flowstone. Stalactites hang from the ceiling, sometimes feeding stalagmites that grow on the floor. All these cave features are produced by calcite-rich water that enters the cave through a long crack along the ceiling. Calcite is calcium carbonate, the major mineral in limestone.
The geological markings under our feet are one indication that the cave-men and -women who operate this site are intent on linking past and present, above- and below-ground.
Cave of the Mounds was discovered in 1939 by workers blasting in a limestone quarry on one of the highest spots in southern Wisconsin. Today, it is a tourist destination with a message — a cool, underground mecca, strategically illuminated, where tour guides leave the nettlesome lectures above ground, and offer easy-to-digest science along the cave’s alleyways.
The above ground section of the site features resurrected prairies and oak savannas, but the main attraction is the stalactites hanging over stalagmites, flowstone, the fossils embedded in ancient limestone, and the rare opportunity to see geology at work as you observe the earth from the inside out.
Drip by drip, water carries calcite, which crystallizes at the bottom of this growing stalactite.
Aftermath of a flood unparalleled
What caused the huge erosion features, ancient shorelines, and scoured potholes in the “channeled scablands” in Eastern Washington state? In 1923, J. Harlen Bretz coined that ominous moniker and proposed that the features had been created by a gigantic flood.
Courtesy Steve Dutch, University of Wisconsin-Green Bay
When Lake Missoula made its mad rush for the Columbia River and the Pacific, vast floods, estimated at 380 meters high, shaped these walls at Wallula Gap.
During this time, geology was ruled by a “uniformitarianism” dogma, which highlighted gradual processes like deposition and erosion, and discounted the power of sudden events like floods (and perhaps even earthquakes, tsunamis and volcanoes).
Skeptics demanded to know the source of all that water in an arid region, and Bretz had a reputation as a kook. Then, geologists gradually realized that the ice-age flood had originated to the east, in glacial Lake Missoula, which had been plugged by the lobe of a glacier emanating from Canada.
In the 1950s, the idea that this huge lake had eaten through an ice dam and then coursed downstream with phenomenal power started gaining acceptance, and in 1979, Bretz, age 96, received the highest award from Geological Society of American for solving this great Earth riddle. Today, scientists believe the floods may have recurred every few years or decades as the ice age was waning, around 14,000 years ago.
Courtesy Steve Dutch, University of Wisconsin-Green Bay
The Columbia River flows through Wallula Gap (left) in Eastern Washington State. During the last ice age, staggering floods resulting from the uncorking of glacial Lake Missoula flowed through the gap. The peak flow is estimated at 10 million cubic meters per second, about “50 times the flow of the Amazon River, ten times the combined flow of all the rivers in the world…” according to geologist Steve Dutch.
The evidence for the floods comes in all sizes. Alternating stacks of coarse gravel and fine sand show gravel left by flood currents under sand left by slower water when the floods receded. A dry river bed called the Grand Coulee, in Eastern Washington, was gouged by the astonishing flow of uncorked glacial melt water. The periodic cascades that shaped Dry Falls, now in Sun Lakes State Park are considered the largest known waterfalls in Earth’s history.
The gypsum dunes at White Sands National Monument are a spectacle best appreciated with sunglasses and a hat!
The unbearable whiteness of being
The world’s largest field of gypsum dunes, at White Sands National Monument in south-central New Mexico, could arouse anybody’s inner drywaller, as gypsum is the mineral basis for both drywall and plaster. But here, where 275 square miles of gypsum dunes have built a hot, severe and scorchingly beautiful landscape, there’s not a sheet of drywall in sight.
White Sands: A land of adaptation
Genetics helps the Apache pocket mouse survive in the white sands.
The bleached earless lizard has adapted to life on a white world. Has it evolved sunglasses to reduce the glare?
Cowles prairie lizard is hard to see against the white sands — and that’s no accident.
Set aside as a national monument by President Herbert Hoover in 1933, the dunes trace their origin to vast deposits of hydrated calcium sulfate — gypsum — that were laid down on an ancient lake a quarter-billion years ago. After a geological uplift, they were exposed roughly 10 million years ago, and eventually moved to the present site in a geologic eye-blink — the last 7,000 years.
Mammoth tracks have been seen in the dunes, but they could get buried with time: Some dunes are moving 30 feet a year, as the wind piles them up on the windward side and gravity avalanches them down the lee.
The gypsum dunes are said to be the largest in the world, but what’s most amazing is not the geology, but the evolutionary adaptations life has used to survive these harsh conditions. At least seven species of animals, including three lizards, that are closely related to darker varieties living in the surrounding desert have turned white for camouflage in this bleached world. (The drywalling lizard or the plastering mouse must be here somewhere!)
Visiting the Sands? Ponder a trip to Trinity, the site of the first test of the atomic bomb.
Sue the Tyrannosaurus rex is ready to meet, greet and eat at Chicago’s Field Museum.
The Windy City boasts not just one, but three cool science destinations, all next door to each other on the Museum Campus along the shore of Lake Michigan.
To explore some of the world’s biological and cultural wonders, spend the day at the Field Museum of Natural History, a collision of anthropology, botany, geology, paleontology and zoology. The permanent exhibits include the DNA Discovery Center, a journey through four billion years of earthly life, and Sue, the largest (and most expensive?) complete skeleton of the ferocious T. rex. Among the temporary exhibits was a recent one on the horse and its deep relationship with humans (an exhibit that particularly excited one horse-crazy Why Filer).
Unassuming by day, the telescope in the Doane Observatory dazzles visitors at night.
If your palate is whetted for a wetter world, walk to the Shedd Aquarium to explore underwater life from the Amazon, the Caribbean and both poles. Green sea turtles, beluga whales, moray eels, piranhas and penguins will be among your hosts.
If otherworldly science is more your thing, visit the Adler Planetarium. Chat about the stars with real space scientists at their Space Visualization Laboratory, or just sit back and watch the star show. Adler’s centerpiece is the Doane Observatory, the largest publicly accessible telescope in the Chicago vicinity. While you can only peer through the lens after dark, this could make for a great conclusion to your trip.
A fresh water crocodile and snaked-neck turtle hang out at the Animal Planet Australia exhibit at the National Aquarium Baltimore.
An Australian freshwater crocodile grows in Baltimore. Seriously. The National Aquarium Baltimore boasts more than 660 species of fish, birds, amphibians, reptiles and mammals, totaling around 16,500 marine creatures.
In addition to its rich marine menagerie, the aquarium has a collection of special exhibits and interactive oceanic enjoyment. See the world through a dolphin’s eyes at Our Ocean Planet, a show that teaches visitors about dolphins and the connections between people and their seafaring friends. Or soak in ocean sensations with a movie at the 4-D Immersion Theater, where you can experience sea life in multiple dimensions, including the smell and feel of (simulated) mist and wind. Or take an expert-led tour, including behind-the-scenes peek of the sharks’ quarters.
The aquarium is also a center for conservation. For example, its Marine Animal Rescue Program tracks the progress of rescued animals after release. Other conservation projects include restoring wetlands and investigating the impacts of mercury on the marine food chain. After all, protecting the life that sustains the ocean ecosystem benefits everyone—not just aquarium visitors.
A humpback whale puts on a show for its human audience.
An excursion exotic to Melville
What’s more breathtaking than seeing the world’s largest animals in the wild? Whale watching puts you up close and personal with these magnificent marine mammals. Since the 1950s, in a 180° turnaround from Herman Melville’s day, people have been flocking by the boatloads to glimpse whales doing what they do rather than to kill them.
Both the U.S. east and west coasts have whales to watch, though you must catch them in the right season during their migration. There’s no guarantee, but on the western seaboard, you could spot orcas and gray whales. The east is home to the right, fin and sei whales. Humpbacks, minkes, and blue whales troll both coastlines.
Several cetaceans (a scientific category including whales, dolphins and porpoises) are endangered, including the North Atlantic right, blue, fin, sei and gray whales. In any case, marine mammals are heavily protected by law, so whale watching should be done with professionals who obey the rules.
Millicent the penguin gets a pat from a new pal at Audubon’s Aquarium of the Americas.
With more than 500 full-time employees and an annual budget exceeding $30-million, Audubon Nature Institute sounds more like a business than a private, non-profit organization dedicated to explaining and preserving the wonders of nature with a Cajun flavor. The group operates a zoo, aquarium and assorted parks in and around New Orleans. The Aquarium of the Americas focuses on the Caribbean, Amazon, Gulf of Mexico (complete with oil-drilling replica) and Mississippi River.
One of Queen Anne’s Revenge’s anchors still looks workable after all these centuries.
A primate exhibit in the Audubon Zoo shows dozens of our opposable-thumbed relatives. Its 360 species of animals include a jaguar shown in a replica Amazon jungle. The “Embraceable Zoo” is devoted to full-contact animal admiration, and you can also eyeball, if not pet, a prickly Indian crested porcupine. Audubon maintains two locations that focus on captive breeding and survival of endangered species; these are closed to the public, but we expect to see you at the new insectarium, located in the old Federal customs house, for the beetle races on Sept. 3.
North Carolina: decapitation capitol
Every summer, vacationers flock to North Carolina’s coast for a beach getaway. But beach vacations would have been a hard sell early in the 18th century, as the coast was the stomping grounds of the South’s most feared pirate, Edward Teach, otherwise known as Blackbeard.
This 1775 map of the Carolina coast show Blackbeard’s native habitat, with Ocracoke Island at center.
Nowadays, the area is proud of its sordid past, attracting pirate-curious tourists and archaeologists alike. In 1996, Blackbeard’s biggest and final ship, Queen Anne’s Revenge, was found off the coast of Beaufort, where it had been hiding for more than 270 years. While the dives did not uncover much treasure, archaeologists estimate the wreckage holds up to 750,000 artifacts, some of which are displayed at Beaufort’s North Carolina Maritime Museum.
Blackbeard is a primary local industry. Ocracoke Island, a favored Blackbeard anchorage, was where he met his fate at the hands of what he mocked as a rabble of “cowardly puppies.” Bath has the legendary ball of light, presumed to be Blackbeard’s ghostly severed head.
So why watch Johnny Depp impersonate a pirate at the multiplex when you can check out the history of this famous scoundrel? Like we said, this old, dead, head-free pirate is a godsend for small business…
This urban, curvy-tusked mammoth is “trapped” in the tar – or in reality, posed in it to represent the thousands of animals that were mired over the millennia since tar started accumulating at La Brea in modern-day Los Angeles, where tar continues to ooze to the surface. (ROLLOVER) The on-site Page Museum is home to a “fish bowl” laboratory, where visitors can watch scientists de-goo specimens.
If you’re stuck for a scientific sojourn in Southern California, head for the pits. Since long before there was a Los Angeles, the La Brea Tar Pits have been an oozing, 3-D flypaper for animals, now with that all-too-trendy urban accent. Asphalt, we learn, is not just good for roads, but also for trapping live animals and preserving their fossils. Since their first description in a scientific publication in 1875, the pits have produced prodigious prizes for paleontology. The onsite Page Museum houses more than 650 species of plants and animals, all removed from the black goo, and dating back 11,000 to 50,000 years.
The tar pits were a graveyard for thousands of carnivores, including the dire wolf, coyote and saber-toothed cat, and a smaller number of herbivores, including mammoth and bison. In an effort to transcend the “heroic” era of paleontology and flesh out (if we can put it that way) a comprehensive picture of life in the era of ice, researchers have recently shifted their focus to fossils of plants and smaller animals, including millipedes, 31 species of mollusks, and 25 species of beetles.
The 27 giant radio telescopes in the Very Large Array move on railroad tracks around a plain in southern New Mexico. Don’t be fooled: each these monsters weighs 230 tons and is 25 meters in diameter! Roll over to see one oddity discovered by the enhanced VLA in 2011.
The newly expanded VLA detected this remnant of a supernova, with that never-before-seen filamentary structure.
Love big? Dig distant, mysterious and unfathomably old? At the Very Large Array, in western New Mexico, you can gawk at 27 giant antennas used by astronomers to “listen” to radio signals from the universe. When you’re done rubber-necking the hardware, check out exhibits at the visitor center.
Then climb an observation tower to get another view of the world’s premier radio telescope zoo. Notice how every single antenna has silently and inexorably changed its orientation, and is now pointing to another invisible spot in the heavens? You are looking at visual proof of our planet’s normally insensible rotation.
It takes a lot of work, and some hefty equipment, to pry loose the secrets of the universe, and here, the scale of the operation is written across the desert. Since 1980, the VLA has, alone or in tandem with other telescopes, been collecting the astrophysical evidence for the formation and destruction of stars and galaxies. The new “enhanced VLA” can “hear” three times as many radio bandwidths as the VLA and is 10 times more sensitive. How sensitive is that? They say it could hear a cellphone calling from Jupiter…
This clever subminiature camera allowed an operative to take photographs while pretending to check his watch for the time of day. The circular film allowed six exposures.
Go under cover in the capital city
Explore life under cover (and the technology that allows a spy to hide in plain sight) at the International Spy Museum, the only public museum of its kind in the United States. With the largest public collection of international espionage artifacts, the museum provides a unique global perspective of this covert profession — said to be the second oldest — and how it has shaped the past and present.
Before you start your mission, you are challenged to adopt a secret identity. As you snoop about, you’ll discover the Secret History of History, which highlights the influence of spies through the ages; gadgets and stories of espionage during the American Civil War, World War II, and Cold War; and a gallery of spy technology. You can even see if you have what it takes to be an agent in the Operation Spy interactive experience, in which you must find a missing nuclear trigger before it ends up in the wrong hands. Just don’t blow your cover!
Visit the “Boneyard”
Warplanes go to the desert to die, and there, for a fee, you can tour thousands of mothballed fighters, bombers and helicopters at the 309th Aerospace Maintenance and Regeneration Center. Bus tours run from the Pima Air and Space Museum, on the outskirts of Tucson, Ariz. With more than 4,200 planes, the “boneyard” is the ultimate in aerial combat nostalgia.
Some of these planes will be scrapped, others may be sold or salvaged for parts, or pressed back into service during future wars. Seldom celebrated, but perhaps more important from a technological point of view, the site also stores 350,000 tools used to make these machines, including, we presume, the one-of-a-kind tools and dies used to shape jet engines, wings and fuselages.
Ogling killing machines may seem macabre, but then, if you are a U.S. taxpayer, you’ve already paid for this stuff… might as well check it out, and witness how the technology of aerial warfare has changed over the decades!
Boneyarders eviscerated these B-52s per an arms-control agreement, the left them in the desert so Soviet satellites could confirm their destruction. Roll over to see the boneyard’s scale.
Movie cameras and projectors were a main interest at the Edison lab. Before machine tools went electric, they were driven by those dangerous belts at upper right. Just curious: How come the lab of Mr. Electricity lacked an electric lathe?
In 1887, after he had patented the first practical electric light bulb, mega-inventor Thomas Edison invented an inventor’s playground in West Orange, N.J., just outside Manhattan. Edison stocked the lab with every resource needed to crank out movie cameras and projectors, teletypes, recording and playback devices, batteries and countless other electric gadgets for the fast-modernizing nation.
With labs focusing on chemistry and physics, and with shops devoted to woodworking and metal-working, Edison could concentrate on his strong points: cranking out ideas and masterminding publicity stunts that helped ensure his commercial success. During World War I, 10,000 people cranked out electrical devices for the military at the factories clustered around the lab. Edison worked at the West Orange lab until his death in 1931.
Think of Edison as primarily an inventor? Then you have to wonder how his name wound up on the companies selling electricity to New York and Chicago. God may have made the Garden of Eden, but Thomas Edison made the garden of invention in north Jersey, and it awaits your visit.
Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant
Why do some rocks break so easily once an earthquake begins? In a giant quake, the fracture, where the two sides of the fault grind against each other, can extend dozens or hundreds of miles. The question has met several answers over the years.
Rock powder — ideal grease for earthquakes?
According to one theory, rocks get hot enough at the break to form a slippery layer of glassy rock along the fault. But that is not entirely satisfactory, says Ze’ev Reches, a professor of geoscience at the University of Oklahoma, because large earthquakes can form where the rocks are too cool to form glass.
“For some reason, friction seems to decline during a break, but what is the mechanism?” he asks.
In a laboratory study in this week’s Nature, Reches and David Lockner of the U.S. Geological Survey showed that a thin layer of rock powder that forms at the break causes a rapid drop in friction, which allows the break to spread further and faster down the fault. “The powder itself is a lubricant and it reduces the friction when it forms,” he says.
To test rock samples, the researchers used a press that rotated one sample against another, producing a motion that was more representative of actual earthquakes, and also much longer and faster than previous researchers have studied. The study showed that a thin layer of rock powder can weaken the fault by at least 50 percent, Reches says.
Courtesy Joel Young and Ze’ev Reches, University of Oklahoma
Using a pressure and velocity that resemble real quakes, this apparatus simulates earthquake slips.
The results concern how rock can slip once a fault breaks. It would be nice to know how the first rupture occurs, Reches says, but conditions in fault zones are so varied “that there is always a place where it’s significantly weaker, or is under a significantly higher load, so it starts moving. The question becomes, how far will this movement go?”
And the answer depends on how much friction remains in the broken portion, he says.
The rotary rock-grinder also showed that the powder, called gouge, ceases to lubricate within hours or days. “Everybody has seen the powder in faults and in experiments, but it was always taken for granted that the gouge does not change its properties,” Reches says. “What we have discovered is fundamentally different: The gouge has to be formed fresh, each time, to obtain this lubrication.”
Courtesy Ze’ez Reches
A close-up of the test apparatus shows lubricating powder that formed when rocks were ground against each other to simulate earthquake movement.
Break, dancing
The original powder is composed of grains that are “a few tens of nanometers across, but then because of adhesion between the grains it starts forming much larger clusters,” Reches says. The small grains can slip against each other, “but once they form these clusters, it takes a lot of energy to break them, so friction rises.”
“The internal workings of earthquake faults is one of the great unsolved problems of geophysics,” says Harold Tobin, a fellow fan of faults who is professor of geoscience at the University of Wisconsin-Madison. “Understanding the friction and mechanisms inside a fault, as it suddenly goes from hundreds of years of building up tremendous stress to rupturing in an earthquake, would help us understand why, where and when earthquakes occur. Experiments like the ones reported by Reches and Lockner are a key tool for getting at how earthquake faults slip.”
The study, Tobin says, is “a window on how an initial cracking turns into an earthquake. In my view, the study is not a game-changer in terms of our understanding of earthquake faults, but it does provide some solid data that will feed into better theories and models.”
Bearing it out
The study could help explain why the many tiny quakes that occur each day do not set off major quakes, Reches says. “In Oklahoma, we have magnitude 2 or 3 quakes but they don’t grow, because the conditions surrounding the break are not suitable. Why an earthquake occurs is not related to the initiation, but to the weakness that allows it to propagate.”
The San Andreas Fault in California is active and deadly.
The phenomenon could also explain the “creeping section” of the San Andreas Fault, near Parkfield, California. Beyond both ends of the 120-mile section, the fault produces lethal, magnitude 8 quakes, Reches says, yet quakes in between release less than 10,000 times as much energy. “Although it’s on such a major active fault, the creeping section accommodates the motion in a very different mode. It might be that the rocks in this zone are not capable, once the motion starts, of creating the gouge that would lubricate it.”
With medium- and large-size earthquakes, Reches says, “the fundamental issue is, what is the mechanism of the weakening? What we have found is that once it starts moving, the formation of gouge makes it much weaker than before the movement started.”
It’s a boom time for studying Mars, and the perfect time for the be-all, end-all summer vacation. Ride a robot rover. Dune-buggy an unearthly dune field. Even meet-and-greet a real live Martian! All aboard for Mars! (more…)
Dating techniques can tell when magma cooled at the surface, revealing the “pulse” of eruptions. 
Above mines and underground streams
Fact: The surface of Mars shows massive erosion and huge fields of sand dunes.
