Newly discovered natural arch in Afghanistan one of world’s largest

Wildlife Conservation Society scientists working in Afghanistan recently discovered one of the largest natural stone arches in the world. -  Ayub Alavi
Wildlife Conservation Society scientists working in Afghanistan recently discovered one of the largest natural stone arches in the world. – Ayub Alavi

Researchers from the Wildlife Conservation Society have stumbled upon a geological colossus in a remote corner of Afghanistan: a natural stone arch spanning more than 200 feet across its base.

Located at the central highlands of Afghanistan, the recently discovered Hazarchishma Natural Bridge is more than 3,000 meters (nearly 10,000 feet) above sea level, making it one of the highest large natural bridges in the world. It also ranks among the largest such structures known.

“It’s one of the most spectacular discoveries ever made in this region,” said Joe Walston, Director of the Wildlife Conservation Society’s Asia Program. “The arch is emblematic of the natural marvels that still await discovery in Afghanistan.”

Wildlife Conservation Society staff Christopher Shank and Ayub Alavi discovered the massive arch in late 2010 in the course of surveying the northern edge of the Bamyan plateau for wildlife (the landscape is home to ibex and urial wild sheep) and visiting local communities.

After making the discovery, they returned to the Hazarchishma Natural Bridge (named after a nearby village) in February 2011 to take accurate measure of the natural wonder. The total span of arch-the measurement by which natural bridges are ranked-is 210.6 feet in width, making it the 12th largest natural bridge in the world. This finding pushes Utah’s Outlaw Arch in Dinosaur National Monument-smaller than Hazarchishma by more than four feet-to number 13 on the list.

The world’s largest natural arch-Fairy Bridge-is located by Buliu River in Guangxi, China, and spans a staggering 400 feet in width. Several of the top 20 largest natural arches are located in the state of Utah in the U.S.

Consisting of rock layers formed between the Jurassic Period (200-145 million years ago) and the more recent Eocene Epoch (55-34 million years ago), the Hazarchishma Natural Bridge was carved over millennia by the once flowing waters of the now dry Jawzari Canyon.

With the assistance of WCS and support from USAID (United States Agency for International Development), the government of Afghanistan has launched several initiatives to safeguard the country’s wild places and the wildlife they contain. In 2009, the government gazetted the country’s first national park, Band-e-Amir, approximately 100 kilometers south of Hazarchishma Natural Bridge. The park was established with technical assistance from WCS’s Afghanistan Program. WCS also worked with Afghanistan’s National Environment Protection Agency (NEPA) in producing the country’s first-ever list of protected species, an action that now bans the hunting of snow leopards, wolves, brown bears, and other species. In a related effort, WCS now works to limit illegal wildlife trade in the country through educational workshops for soldiers at Bagram Air Base and other military bases across Afghanistan. WCS also works with more than 55 local communities in Afghanistan to better manage their natural resources, helping them conserve wildlife while improving their livelihoods.

“Afghanistan has taken great strides in initiating programs to preserve the country’s most beautiful wild places as well as conserve its natural resources,” said Peter Zahler, Deputy Director for the WCS Asia Program. “This newfound marvel adds to the country’s growing list of natural wonders and economic assets.”

EarthScope seismic sensors head east of the Mississippi

An engineer tests the EarthScope Transportable Array Station 345A after the electronics are installed. The seismometer is in the center. -  Courtesy of IRIS
An engineer tests the EarthScope Transportable Array Station 345A after the electronics are installed. The seismometer is in the center. – Courtesy of IRIS

Most seismic activity–and earthquakes–have been in the U.S. West. But the East is not out of the woods in terms of risk, geologists say.

After a six-year march eastward from the U.S. West Coast, the EarthScope Transportable Array seismic network has reached a major milestone: installation of the first Transportable Array station east of the Mississippi River.

Station 345A, located on a private farm about 15 miles northwest of Columbia, Miss., will operate for the next two years, continuously recording ground motion from local, regional and global earthquakes.

The Transportable Array is part of the National Science Foundation (NSF)-funded EarthScope project, an integrated Earth science effort to explore the structure, evolution and dynamics of the North American continent.

EarthScope has additional support from NASA and the U.S. Geological Survey. The Transportable Array is constructed, operated and maintained by the Incorporated Research Institutions for Seismology (IRIS) as part of EarthScope.

“Research using data from the Transportable Array has already improved our understanding of the structure and dynamics of the western United States,” says Greg Anderson, NSF program director for EarthScope.

“With the arrival of the Transportable Array in the eastern United States,” Anderson says, “scientists will derive new insights about the older core of our continent and processes related to the formation and modification of continents over geologic time.”

Because the Western part of the country regularly experiences earthquakes that can be felt, “the region has dozens of permanent seismometers to observe fault movements,” says Bob Woodward, director of the USArray, the seismic component of EarthScope.

“Seismic stations east of the Mississippi River are much less common.”

The Transportable Array network comprises a grid of 400 state-of-the-art seismic stations installed about 70 kilometers apart.

Each station is a stand-alone system with a seismometer and electronic equipment installed about six feet below ground and solar panel and communications equipment at the surface.

Most Transportable Array stations, like 345A, have been installed on private land; the landowners serve as volunteer hosts and are enthusiastic about advancing knowledge of Earth’s inner workings.

To date, Transportable Array stations have been installed in more than 1,100 locations, out of an expected 1,600 by the end of the first ten years of EarthScope in 2013.

These stations have recorded over 22 terabytes of data that are freely available to Earth scientists, educators and the public across the U.S. and around the world.

Novel technique reveals how glaciers sculpted their valleys

A numerical model provides snapshots every 250,000 years of the evolution of the Neale Burn drainage in Fiordland, New Zealand, during the last 2.5 million years. Over this time, the glacier cut into the flanks of the mountain at the mouth of the drainage, and later cut further toward the headwaters.

The white line in the upper panel is the centerline of the Neale Burn valley, while the dots show the location of elevation profiles referred to in the lower panel. The middle panel shows the local lowering rate (i.e., erosion rate minus uplift rate) along this profile, as calculated for the preceding 250,000 years of each time frame. -  David Shuster and Kurt Cuffey, UC Berkeley
A numerical model provides snapshots every 250,000 years of the evolution of the Neale Burn drainage in Fiordland, New Zealand, during the last 2.5 million years. Over this time, the glacier cut into the flanks of the mountain at the mouth of the drainage, and later cut further toward the headwaters.

The white line in the upper panel is the centerline of the Neale Burn valley, while the dots show the location of elevation profiles referred to in the lower panel. The middle panel shows the local lowering rate (i.e., erosion rate minus uplift rate) along this profile, as calculated for the preceding 250,000 years of each time frame. – David Shuster and Kurt Cuffey, UC Berkeley


The beautiful and distinctive U-shaped glacial valleys typical of alpine areas from Alaska to New Zealand have fascinated and frustrated geologists for centuries.

While it seems obvious that glaciers scoured the bedrock for millions of years, what the landscape looked like before glaciers appeared, and how the glaciers changed that landscape over time, have remained a mystery. The glaciers erased all the evidence.

Now, University of California, Berkeley, and Berkeley Geochronology Center (BGC) scientists have employed a clever technique to reconstruct the landform history of a 300-square-mile area of Fiordland in New Zealand, from the early Pleistocene some 2.5 million years ago, when the world cooled and glaciers formed, through today’s warmer interglacial period.

“The first question we asked was, how much of the current landscape and relief is a result of glacial erosion?” said David Shuster, who developed the novel technique, called helium-4/helium-3 thermochronometry. “The answer is, all of it.”

Shuster is an associate adjunct professor of earth and planetary science at UC Berkeley and a geochemist at the Berkeley Geochronology Center.

“Geologists have wondered, what did the landscape look like 200,000 years ago, or 400,000 years ago, or back before the Pleistocene glaciations began?” said glaciologist Kurt Cuffey, professor and chair of geography and a professor of earth and planetary science at UC Berkeley. “Did the valleys start out as V-shaped canyons submerged in ice, and the glacier just widened and deepened them? Or perhaps the relief was sculpted by glaciation, and it didn’t matter what the rock landscape looked like before.”

“David’s work opens up a whole new world of investigation to tell us how the alpine landscape progressed, with implications for how glaciers today act on the landscape,” he said.

Shuster, Cuffey, UC Berkeley graduate student Johnny Sanders and BGC researcher Greg Balco report their conclusions in the April 1 issue of the journal Science.

Glaciers carved their mouths first, then their heads


The team found that in the Fiordland, a well-known tourist destination in the Southern Alps of New Zealand, the rock currently on the surface was about 1.5 miles (2 kilometers) underground when the glaciers began forming about 2.5 million years ago. Since then, the mountains rose as a result of tectonic activity, while the glaciers flowed downhill, scouring the landscape and gouging U-shaped valleys on their way to the sea.

What surprised the geologists was that most of the valley-making occurred at the downstream mouths of glaciers for the first million years, essentially stopping about 1.5 million years ago. For the next million years, until about 500,000 years ago, erosion took place primarily at the heads of glaciers, which steadily ate into their headwalls, characterized by steep, amphitheater-like cirques. As a result, the deep valleys advanced up their drainage basins toward the range divide, producing razorback ridges in the process.

“Apparently, the heads of glaciers would be directly opposite one another on either side of a high ridge, and faster erosion at the headwalls caused the glaciers to eat their way inward to the spine of the mountain range, farther from the glacier’s outlet,” Cuffey said.

Major changes to the mountain topography essentially stopped about half a million years ago. The current interglacial period started about 12,000 years ago, after warming temperatures caused the glaciers to melt and recede. The fact that these Fiordland valleys are now ice-free allowed the researchers to collect surface rock samples from 33 sites in four glacial valleys over six days with the assistance of a helicopter. The valleys end in Milford Sound or Lake Te Anau.

Temperature as a proxy for depth

Shuster developed helium-4/helium-3 thermochronometry while a graduate student at Caltech, from which he obtained his Ph.D. in 2005. The technique makes it possible to determine the temperature of a mineral as it cooled over geological time. Because temperature increases with depth, the temperature history of the mineral tells how deeply it was buried over a period of millions of years.

“The technique allows us to collect samples from the present surface and, based on observations, infer how they cooled through 80 degrees Celsius to 20 degrees Celsius (176 to 68 Fahrenheit) over the last few million years, and thus, how deep they were when they cooled,” Shuster said.

At the moment, the technique works only with crystals of apatite, a calcium phosphate mineral found mainly in plutonic rocks, such as granite, that solidify from magma deep underground. The apatite crystals contain uranium and thorium, which over millions of years decay radioactively, producing helium-4. The helium gradually leaks out of the crystal into the surrounding rock, but the rate of leakage decreases as the crystal cools.

Using special equipment at the BGC, the geologists were able to date the cooling of the minerals by measuring the amount of uranium and thorium in each crystal as well as the total amount of helium-4. The new technique involves irradiating the crystal with a proton beam to create helium-3, then measuring the outgassing of both helium isotopes to obtain a cross section of the helium-4 concentration in the crystal. They then calculated the crystal’s cooling history based on the helium diffusion rate.

The samples, all of them younger than 2.5 million years, showed a large range of temperature, and thus depth, histories. Cuffey and Shuster used a computer model to test various scenarios and concluded that only one fit the data: Glaciers initially scoured the U-shaped valleys on the flanks of the mountain range, and only later began eating away at their headwater regions, including cirques and drainage divides.

“? this morphology resembles modern analogs in Norway and Antarctica, where steep valley ramps descend to level floors,” the authors wrote.

The common thread is that the rock erodes faster where the ice sits on a steep slope, they said. Thus, the erosion rate of a glacier is greatest where the flowing river of ice descends steeply downstream.

“This scenario is consistent with a subglacial erosion rate dependent on ice sliding velocity, but not ice discharge,” Shuster said.

Study sheds light on how heat is transported to Greenland glaciers

Using a tiny boat and a helicopter, the research team returned to Greenland in March 2010, to do the first-ever winter survey of Sermilik Fjord at the base of Helheim Glacier. During the trip, they were able to launch probes closer to the glacier than ever before -- about 2.5 miles away from the glacier's edge. -  Fiamma Straneo, Woods Hole Oceanographic Institution
Using a tiny boat and a helicopter, the research team returned to Greenland in March 2010, to do the first-ever winter survey of Sermilik Fjord at the base of Helheim Glacier. During the trip, they were able to launch probes closer to the glacier than ever before — about 2.5 miles away from the glacier’s edge. – Fiamma Straneo, Woods Hole Oceanographic Institution

Warmer air is only part of the story when it comes to Greenland’s rapidly melting ice sheet. New research by scientists at Woods Hole Oceanographic Institution (WHOI) highlights the role ocean circulation plays in transporting heat to glaciers.

Greenland’s ice sheet has lost mass at an accelerated rate over the last decade, dumping more ice and fresh water into the ocean. Between 2001 and 2005, Helheim Glacier, a large glacier on Greenland’s southeast coast, retreated 5 miles (8 kilometers) and its flow speed nearly doubled.

A research team led by WHOI physical oceanographer Fiamma Straneo discovered warm, subtropical waters deep inside Sermilik Fjord at the base of Helheim Glacier in 2009. “We knew that these warm waters were reaching the fjords, but we did not know if they were reaching the glaciers or how the melting was occurring,” says Straneo, lead author of the new study on fjord dynamics published online in the March 20 edition of the journal Nature Geoscience.

The team returned to Greenland in March 2010, to do the first-ever winter survey of the fjord. Using a tiny boat and a helicopter, Straneo and her colleague, Kjetil VĂ¥ge of University of Bergen, Norway, were able to launch probes closer to the glacier than ever before-about 2.5 miles away from the glacier’s edge. Coupled with data from August 2009, details began to emerge of a complicated interaction between glacier ice, freshwater runoff and warm, salty ocean waters.

“People always thought the circulation here would be simple: warm waters coming into the fjords at depth, melting the glaciers. Then the mixture of warm water and meltwater rises because it is lighter, and comes out at the top. Nice and neat,” says Straneo. “But it’s much more complex than that.”

The fjords contain cold, fresh Arctic water on top and warm, salty waters from the Gulf Stream at the bottom. Melted waters do rise somewhat, but not all the way to the top.

“It’s too dense,” Straneo says. “It actually comes out at the interface where the Arctic water and warm water meet.” This distinction is important, adds Straneo, because it prevents the heat contained in the deep waters from melting the upper third of the glacier. Instead, the glacier develops a floating ice tongue-a shelf of ice that extends from the main body of the glacier out onto the waters of the fjord. The shape of the ice tongue influences the stability of the glacier and how quickly it flows.

In addition, the team found that vigorous currents within the fjord driven by winds and tides also play a part in melting and flow speed. “The currents in the fjord are like waves in a bath tub,” Straneo says. “This oscillation and mixing contribute to heat transport to the glaciers.”

The March 2010 trip marked the first time the researchers were able to observe winter-time conditions in the fjord, which is how the system probably works nine months out of the year.

“One surprise we found was that the warm waters in the fjord are actually 1 degree Celsius warmer in winter, which by Greenland standards is a lot,” Straneo says. “It raises the possibility that winter melt rates might be larger than those in the summer.

“Current climate models do not take these factors into account,” she adds. “We’re just beginning to understand all of the pieces. We need to know more about how the ocean changes at the glaciers edge. It’s critical to improving predictions of future ice sheet variability and sea level rise.”

Wind can keep mountains from growing

Researchers sit atop a wind-formed ridge called a yardang located in the Qaidam Basin of Central Asia. The yardangs in that area can be as much as 40 meters (about 130 feet) tall and about a football field (100 meters) apart. -  Paul Kapp, University of Arizona.
Researchers sit atop a wind-formed ridge called a yardang located in the Qaidam Basin of Central Asia. The yardangs in that area can be as much as 40 meters (about 130 feet) tall and about a football field (100 meters) apart. – Paul Kapp, University of Arizona.

Wind is a much more powerful force in the evolution of mountains than previously thought, according to a new report from a University of Arizona-led research team.

Bedrock in Central Asia that would have formed mountains instead was sand-blasted into dust, said lead author Paul Kapp.

“No one had ever thought that wind could be this effective,” said Kapp, a UA associate professor of geosciences. “You won’t read in a textbook that wind is a major process in terms of breaking down rock material.”

Rivers and glaciers are the textbook examples of forces that wear down mountains and influence their evolution.

Wind can be just as powerful, Kapp said. He and his colleagues estimate wind can be 10 to 100 times more effective in eroding mountains than previously believed.

The team’s paper, “Wind erosion in the Qaidam basin, central Asia: implications for tectonics, paleoclimate, and the source of the Loess Plateau,” is in the April/May issue of GSA Today.

Kapp’s co-authors are Jon D. Pelletier and Joellen Russell of the UA; Alexander Rohrmann, formerly of the UA and now at the University of Potsdam in Germany; Richard Heermance of California State University, Northridge; and Lin Ding of the Chinese Academy of Sciences, Beijing. The American Chemical Society Petroleum Research Fund and a UA Faculty Small Grant funded the research.

The geoscientists figured out wind’s rock-sculpting abilities by studying gigantic wind-formed ridges of rock called yardangs.

Kapp first learned about yardangs when reviewing a scientific paper about Central Asia’s Qaidam Basin. To see the geology for himself, he booted up Google Earth — and was wowed by what he saw.

“I’d never seen anything like that before,” he said. “I didn’t even know what a yardang was.”

Huge fields of yardangs that can be seen from space look like corduroy. Wind had scoured long gouges out of the bedrock, leaving the keel-shaped ridges behind. Kapp wondered where the missing material was.

The team’s initial research was conducted using geological maps of the region and satellite images from Google Earth. Then Kapp and his team went to the Qaidam Basin to collect more information about the yardangs, the history of wind erosion and the dust.

“What we’re proposing is that during the glacials, when it’s colder and drier, there’s severe wind erosion in the Qaidam basin and the dust gets blown out and deposited downwind in the Loess Plateau,” Kapp said.

The term “loess” refers to deposits of wind-blown silt. Parts of the U.S. Midwest have large deposits of loess.

“Up until 3 million years ago, the basin was filling up with sediment,” he said. “Then like a switch, the wind turned on and basin sediments get sandblasted away.”

Known as the “bread basket of China,” the Loess Plateau is the largest accumulation of dust on Earth. Scientists thought most of the dust came from the Gobi Desert.

In contrast, Kapp and his colleagues suggest more than half of the dust came from the Qaidam Basin. Co-author Pelletier, a UA geomorphologist, created a computer model indicating that dust from the basin could have formed the plateau.

The wind is not having such effects now because the climate is different, Kapp said. Co-author Russell plus other research groups suggest the westerly winds shift north during interglacial periods like that of the current climate and shift toward the equator during glacial periods.

Therefore since the last Ice Age ended about 11,000 years ago, the winds have blown from the Gobi Desert toward the Loess Plateau. During glacial periods, the winds blew from the Qaidam basin toward the Loess Plateau instead.

“During the interglacials, the basin fills up with lakes. ? When it goes back to a glacial period, lake sediments blow away,” he said. “Our hypothesis is that you have lake development, then wind erosion, lake development, wind erosion, lake development – and so on.”

The team suggests wind erosion also influenced how fast the basin’s bedrock is folded. In Central Asia, bedrock folds and crumples because it’s being squeezed as the Indian plate collides with the Asian plate.

“The folding accelerated 3 million years ago,” Kapp said. “That’s when the wind erosion turned on. I don’t think it’s a coincidence.”

During the glacial periods, the winds whisked sediment out of the basin. As a result, the bedrock deformed faster because it was no longer weighed down by all the sediment.

Kapp calls the process “wind-enhanced tectonics.” The term “tectonics” refers to forces that cause movements and deformation of the Earth’s plates.

The whole process is driven by global climate change, he said. “The unifying theme is wind.”

Kapp and his team are quantifying the processes further as they analyze more samples they brought back from the Qaidam basin and Loess Plateau.