On Saturday morning, Ed and I left Pretoria for the next phase of our trip: field work near the Loskop Dam in Mpumalanga Province where a large volcano once existed about two billion years ago. No one has been able to find where this ancient volcano stood but lava flows in the area suggest there was once volcanic activity. We will be collecting rocks and analyzing their structure to piece the story together.
On our way, we passed through Witbank, one of South Africa’s largest coal-mining operations. From the road, we spotted the coal plants’ big cooling towers as well as coal trucks parked along the road.
The Loskop dam area where we will be working for the next several days is more mountainous than Pretoria, with cliffs and rolling hills. The dam is also a spectacular structure that has created a large lake where crocodiles and hippos like to hang out. Unfortunately, the extensive mining in this region, at Witbank and the Bushveld Complex, has taken an ecological toll. Acid from the mines has drained into the lake, gnawing away at the bones of the crocodiles living there. Only juvenile crocodiles live there now.
One lava formation that we will be studying is called the Damwal, or “Dam Wall.” Nearby are several game reserves where Impala, Kudu, Zebra, and Wildebeest are raised. The game keepers have warned us about the leopards that live in some of the surrounding mountains and valleys. We’ve been told about a wild leopard breeding area in the valley across the river where animal carcasses are often found dangling from the trees.
Luckily for us, a tall wire fence lines most of the road where we are working and the only animals we’ve seen so far are baboons. We typically sample along the road, not out of laziness but because this is where the rock is most exposed. (Road building often involves blasting away rock, creating fresh surfaces that have not been exposed to weathering for very long.) It is much easier to collect here than to dig through layers of sediment or hammer away at boulders.
After a morning lecture about the Bushveld Complex and the processes of concentrating ores in magma bodies, Ed and I had to go to the University of Pretoria for Thursday afternoon. I was invited to give a lecture and we were able to have some very interesting conversations about Bushveld research with the people who have been working on it for many years.
While we were gone, Natasha, Jay and Chris helped the teachers develop presentations for sharing the material they learned this week with other teachers. Nearly all said they would start incorporating the material into their lesson plans immediately. Each teacher sees 200 to 300 students per day. With 20 teachers in our workshop, this means that 4,000 to 6,000 students will potentially benefit. If the teachers pass on this knowledge to other teachers, the impact could be even greater.
Friday was the last day of our workshop. The teachers gave their presentations and we gave each one a certificate for participating. We have had so many great discussions about geology, education, global economies, global politics, and so much more. I have learned so much from each one of them. The teachers also had presents for us–a vuvuzela and South African flag and futbol scarf for each of us. Our day ended with singing, clapping and smiling.
We woke up Wednesday morning to find out that all unionized government workers, including public school teachers, were on strike. All schools were shuttered and we worried that no one would show up for our workshop.
But we arrived at class to find all of our teachers present. They told us this was a once in a lifetime opportunity and they didn’t want to miss a moment.
For the day’s activities we traveled to the Cullinan diamond mine, where one of the world’s largest diamond—the Star of Africa—was discovered. With help from a Cullinan tour guide, Ed and I discussed how diamonds form deep in the Earth. The mine is still active today and we watched as rock was transported to the surface to be crushed and washed for diamond separation. This sparked a discussion about the types of careers that are available in the mining industry – everything from geologists to engineers to miners to doctors.
After the trip, we talked about other potential field trips and how to plan a teaching curriculum around them. One major reason I went into geology was to be out in the field exploring. Field trips are a great way to teach students to observe the world around them and gain a deeper understanding of the subject material.
Our teaching workshop continued Tuesday with a lecture about mineral resources and their economic importance. South Africa has abundant platinum and gold but also lesser-known elements like vanadium, chromium, and manganese. Vanadium and chromium, important to the steel industry, are found predominantly in the Bushveld Complex where our research is focused. Chromium gives steel much of its strength while vanadium stabilizes it to prevent expansion and contraction, allowing oil pipelines in Alaska and Russia, for instance, to resist cracking during extreme temperature swings.
Later that day I gave lectures on the formation of coal and gold, two of South Africa’s leading resources. The country gets more than 75 percent of its energy from coal and more than 40 percent of the gold mined on Earth has come from the Witwatersrand deposit near Johannesburg. Some estimate that more than 50 percent of the world’s reserves still remain here. In fact, the discovery of the ‘Rand’ deposit is what led to Johannesburg’s founding. The South African currency, the rand, is named for this gold deposit.
The teachers seemed to especially appreciate Chris Emdin’s discussion of how to engage students in the classroom–here students are called “learners” – to explore the material on their own terms. South Africa has 11 official languages. While all formal education and exams are done in English, English is almost never the student’s first language. This makes science especially challenging to teach. Chris showed the teachers one activity for helping students translate vocabulary words across English, science, their native language and slang. This way the students can incorporate the words they hear in class into their lives.
During the morning session one teacher told me that he had gone through five textbooks the night before searching for text on plumes, or hot spots. My lecture the previous day had discussed how islands like Hawaii, Iceland, and Reunion – off the coast of Madagascar – form from magma rising deep from Earth’s mantle. The teacher told me that in Afrikaans there is no word for “plume” and that none of his textbooks included it. He asked me for a definition and some pictures and said he would approach the Afrikaans textbook publishers in Johannesburg about including the term in their next editions.
The workshop that we are here leading is designed to help South Africa high school teachers make geology come alive for their students. We want to share basic concepts, such as how rocks and minerals form, but also provide activities and materials that can make the concepts more accessible.
In planning the workshop, we outlined basic geologic themes that we wanted to get across: geologic time, plate tectonics and the rock cycle. As the “themes ambassador,” I’ll be giving lectures on all three topics on the first day of the workshop.
It was an exhausting first day but rewarding. The high school teachers were so engaged and asked so many great questions that both of my lectures went significantly over the time limit. We discussed how teaching geologic time can conflict with religious teaching, the formation of hot spots and how volcanoes can impact climate. After the first lecture, Jay shared some simple activities around plate tectonics and plate motions that the teachers could reproduce in their classrooms.
After the rock cycle lecture, Jay hosted a show-and-tell with our New York City rocks. He explained to the teachers that he typically gets his rocks for free at city construction sites. Usually the construction companies pay people to haul the rocks away so workers are happy to let Jay take as many as he wants. The teachers clapped and applauded when he handed out our samples of Manhattan schist, a metamorphic rock, Palisades sill, an igneous rock, and New Jersey arkose, a sedimentary rock, for them to take back to their classrooms. He also distributed a map showing where the rocks were collected and discussed how the teachers could make a similar map for rocks in their area.
It was a great first day and I’m looking forward to a fun and educational week.
We arrived in the city of Tshwane (formerly named Pretoria) on Sunday after a day-long journey from New York. Tshwane is the executive capitol of South Africa and according to several locals we met while walking through the city, home to the most national embassies after Washington D.C. More importantly, Tshwane is where the U.S. defeated Algeria in the World Cup just two months ago. The city is dear to my heart because it is where my grandfather came many years ago for surgery while working for a hunger relief program in Zambia.
We spent the day exploring the city and trying to beat our jetlag. We visited the spectacular gardens surrounding the city’s government buildings as well as the former home of Paul Kruger, the president of South Africa before the British took control from the Boers, or its Dutch-speaking settlers, in 1900. The Kruger House Museum chronicles the Transvaal and Boer Wars and showcases the furniture, clothing and even kitchen appliances of late 19th Century South Africa.
We later stopped at a café near the main square and got a much-needed caffeine jolt and tried “biltong,” a type of cured meat made from wild game that tastes like prosciutto. On our way to our hotel, we passed Tshwane’s Brooklyn neighborhood and joked about traveling 24 hours just to end up where we started.
I’m flying to Johannesburg on Friday in what will be my third expedition to South Africa. In the past I’ve traveled here to study the Bushveld Complex, a huge lava formation that provides over 70 percent of the world’s platinum as well as other valuable ores, such as vanadium and chromium, both used to make steel.
This year I’ll continue my fieldwork in the Bushveld but first we will provide a week of geology-education training to South African high school teachers from Pretoria and the surrounding areas. South Africa’s mines provide the single largest source of jobs in this country yet most South Africans know little about the earth processes that created its mineral wealth—its gold, diamonds, platinum and coal. Over five days, we will provide lectures and hands-on activities that the teachers can use in their classrooms. We hope to teach basic geologic concepts through the lens of how and where different ores form.
The workshops grew out of conversations that my Ph.D. advisor, Ed Mathez, and I had with our Bushveld hosts since my first visit in 2006. That year Ed and I brought many gifts for the local landowners who allowed us access to their farms so that we could chisel away chunks of rock on their property. These gifts were mainly hats, t-shirts, and children’s toys. But when we asked what they would like us to bring on future trips they overwhelmingly answered “education.”
Back in New York City, at the American Museum of Natural History (AMNH), where Ed is a curator of the petrology collection, we worked with the education director, Maritza MacDonald, to plan the workshop we will hold in Pretoria next week–a collaboration between AMNH and the South African Agency for Science and Technology, funded in part by the National Science Foundation. The workshop has evolved substantially since then with help from three other New York City educators who will accompany us: Natasha Cooke-Nieves, Christopher Emdin, and Jay Holmes.
Right now we are busily boxing up our educational materials: books on coal and platinum, movies produced by the AMNH, maps, posters, and even a few New York City rocks—pieces of Manhattan schist and the Palisades Sill and even beach sand from Coney Island and Far Rockaway. We will use these samples to show the teachers how to make a “geological” map by collecting different rocks from nearby areas.
For the second half of our trip, Ed and I will drive to the eastern-most part of the Bushveld Complex, approximately 2.5 hours away. We are investigating how this huge amount of magma rose from Earth’s mantle into the crust more than two billion years ago and how it cooled and solidified to become what it is today.
I’m preparing for this leg of the journey by studying geological maps of the area, like the one pictured above. Because the Bushveld is so old and has had so much time to erode away, we need precise geological maps to tell us where we might find the rocks at the surface today. The map above will tell us where we can find samples of the Bushveld Complex (the green) and also Bushveld-related lavas (the red, pink, and yellow). The white stickers on the map represent samples collected by others in the past. But I will tell you more about that in the coming posts.
A final note (for now) on the expedition to recover ice cores from the top of Puncak Jaya in Papua, Indonesia: the cores arrived safely on Thursday, July 22, at Ohio State University’s Byrd Polar Research Center, and are now in a special freezer. In coming months, the team hopes to extract and interpret climatic histories from them.
In summary, we successfully recovered three ice cores from two peak locations at the Northwall Firn glacier, from June 9 to 23, 2010. At the Puncak Sumantri peak, we drilled to bedrock, recovering two cores 30 meters long each. At the Puncak Soekarno peak, we recovered 26 meters of ice, but we had to stop before reaching the bedrock, due to time constraints.
In addition to the difficult terrain, the other challenge turned out to be the weather, which underwent extreme, unpredictable changes in short times. We saw cold at night (as low as minus 14 degrees C) go to bright sun in the morning (2 to 8 degrees C), then to foggy conditions and torrential rain. Unpredictable high winds and lightning were also big concerns; in fact, more than one of our tents toppled due to high winds. During our two weeks on the ice, we saw snow four times, covering 3-5 inches each time. However, due to daily rainfall and above-freezing temperatures, the snow melted away in less than a day. Due to the high rainfall and above-freezing temperatures during the day, these glaciers are in fast retreat.
I am happy that I was able to camp safely on the ice for over a week–a lifetime achievement for me, as I usually work at sea level.
I have reached Jakarta, and so have the ice cores, which are being kept frozen while awaiting air shipment to the United States. The rest of the team has already returned to their homes. Next for me: back to sea level, on two research cruises that will add oceanographic information to the data we gathered on Puncak Jaya. Below: a section of core, straight out of the glacier.
Nano and I took the train to Rome to meet a colleague for lunch, and after we explored the old city. I have been through Rome a number of times, making my way to and from Calabria, but this was my first time really seeing the city. Nano was a fantastic tour guide. He was born in Florence but moved to Rome as a kid in the 1950s. He lived next to the Roman Forum before his family moved to Lanuvio.
By chance we discovered a fabulous museum–just three years old but built on the ruins of the Imperial forums, the Roman Empire’s political, economic and religious center. We walked through the same halls and archways that the Romans used while shopping for cloth and meat 2,000 years ago. The ruins and artifacts were beautiful on their own. However, the most fantastic thing about this museum was an exhibit unrelated to the ancient artifacts.
In the 1950s, film director Federico Fellini invited New York photograper William Klein to capture the Italy depicted in his films and these are the pictures we saw on display.
In one room, we encountered five photographs interspersed among limestone pillars, statues of Caesar, and pieces of the Temple of Venus. It was a setup I have never seen before, but somehow both exhibits became more powerful because of this juxtaposition.
This mixing is what strikes me most about Italian life. I noticed it in Caccuri, when I saw great great-grandmothers gossiping with great great-granddaughters on the street. Americans aren’t as proficient at fluidly mixing generations. I noticed it in Placanica, in southern Calabria, when Nano and I went to a town festival of the patron saint, Saint Antonio. Here, there were people of all ages sitting in the church, praying and leaving offerings. Outside the church, the scene resembled a dance club with loud music, dancing, yelling and laughter.
The juxtaposition was strange, yet wonderfully beautiful. In Rome I saw it again in the mixing between massive, ancient buildings and daily life. In pictures, those Roman landmarks, the Forum and Colosseum, look isolated and rural. But in real life they are integrated with modern street life. You turn your head to check for traffic, and see an ancient wall looming over modern buildings.
The most memorable sight came at the end of my trip. I was riding the train through the outskirts at Rome, staring at the farms just starting to appear on the landscape. The sun was setting over the Tyrrhenian Sea and casting long, orange rays across the fields. At just the right moment, I noticed a man seated on a bale of hay, his back to the setting sun. Just 200 meters in front of him, an enormous Roman aquaduct passed overhead–a blend of past and future.
How do we connect the two? How do we prevent ourselves from repeating our mistakes? Perhaps we need to do as the Romans do and intertwine the generations a little bit more.
This spectacular video takes you above Puncak Jaya and vicinity via helicopter, and into the ice camp. Created by videographers David Christenson, Greg Chmura and Ario Samudro, it was forwarded by Scott Hanna of the Freeport McMoRan mning company, which provided heavy logistical support for the ice-coring mission (including the helicopter itself).
I grew up in a family that drove on vacations, be it six hours to the beach, eight hours to see relatives, or three days to Idaho. So the seven hour drive from Calabria to Rome is no big deal, although the lack of air conditioning does make it undesirable. When I tell my friends from the Crotone Basin that I’m driving to Rome, I get astonished comments about the distance.
This year, Nano and I stopped to hike Mount Pollino, 2,250 meter peak in the southern Apennines, not far from where we were working. It makes me smile to imagine how the Calabrians would react if they knew we were driving to Rome and stopping for a five hour hike with a 750 meter elevation rise.
It was a beautiful hike and wonderful way to end the field season. Nano had walked it a few years before and was showing me the way. The trail is not easy to find, and even more difficult to stay on. At one point, he turned off a large dirt path onto a small one. I asked, “Why did you go this way?” He shrugged: “I follow the horses.” A true Calabrese response. It turned out the large dirt road also worked, but the horse path was definitely more pleasant.
Nano described the change in vegetation as we climbed; the Maggiociondolo, with their beautiful hanging flowers; the Fagi, a type of birch tree, but much more knobby; and the Pini Loricati, a stunning tree that lives only at high elevation, in harsh weather. They originated in the Balkans and migrated to the Apennines during periods of glacial advance.
Italians call them “Loricati” because their bark resembles the armor used by the Roman armies.
We hiked in four stages. First, we skirted the bottom of Serra del Prete, the mountain next to Pollino, and climbed 1,500 meters. Stage two was a long and steady climb to a large field, with a herd of cattle and a bar for hikers to stop for a café. Stage three was a steep climb to 2,000 meters, through Fagi trees and near the top, Pini Loricati. Stage four was rough, with 250 meters to go. Wind, no tree cover, unsteady footing on limestone blocks. At 2,150 meters we came across an old, sturdy Pino Loricato. How could anything live up here, much less thrive?
At the crest it’s one more valley, covered in snow, and one more peak to the summit. We rest and have lunch at the top, protected from the wind, and then slowly make our way back down and finish our trip to Rome.
We have finished our mission at Puncak Jaya and removed the ice cores, along with all camps and people from the field. Currently, we are in the coastal city of Timika for a few days, drying out our field equipment and tents. These are the first glaciers we have ever drilled where it rains almost every day–and as a consequence, the glaciers are falling apart.
I think we have been just in time to salvage a bit of the climate history before these glaciers disappear. After two weeks of camping on the ice, the tents we installed were on raised ice platforms about 30 centimeters above the surrounding surface. This speaks volumes as to just how rapidly these glaciers are shrinking. If that two-week period is representative of the annual process, we are talking about meters of ice being removed from the surface of these ice fields each year.
Next challenge will be getting the ice cores and equipment through Indonesian customs. If the journey in is any indication, this could take weeks. The cores are now being stored in a freezer in downtown Jakarta.
One of the challenges of studying the Calabrian subduction zone is the enormous variation over relatively short distances. Etna is located just 120 kilometers from Stromboli, yet the volcanoes have completely different sources of magma. Fluvial conglomerates in the Crotone Basin have lots of chert, yet conglomerates of the same age just 15 kilometers to the south don’t have any.
On our last day of fieldwork, Nano took me just north of the Sibari Basin, at the southern tip of the Apennines, to investigate another dramatic shift. Here, we are looking at the transition from subduction to collision. An oceanic plate (like the Ionian Sea, east of Calabria) can be subducted easily: it’s made of oceanic crust, which is often colder, older, and more dense than the plate next to it. However, in space, oceanic crust transitions into continental crust, which is warm, young, and less dense. For example, the crust under the Atlantic Ocean is oceanic near the Mid-Atlantic Ridge, but continental off the coast of the United States.
The situation is similar in the Mediterranean. The Ionian Sea is made of oceanic crust but on its southern edge, the crust transitions into the African continental crust. In addition, just north of the Crotone Basin, the oceanic crust transitions into the Apulian Platform, a piece of continental crust that extends from the Gargano Peninsula to the Salento Peninsula. Since the Apulian Platform is too buoyant to subduct, the two plates are colliding, building mountains, and their convergence rate is slowing down. However, a few kilometers to the south, subduction continues and the convergence rate is steady.
To understand and work through this problem, I like to picture a comedic sketch in which someone carrying a two-by-four lengthwise tries to walk through a doorway. One side of the two-by-four hits the wall and generates the Apennines while the other side hits the wall and generates the Maghrebides in Sicily. Calabria is stuck in the door. Since tectonics continue to force Calabria through the open door, the parts that are stuck must somehow detach so that Calabria can push forward and continue subducting.
Most commonly, scientists think this process is accomplished through a vertical shear zone, or strike-slip fault. So the two by four behaves more like a piece of foam that will bend around the corners and eventually break completely. In the Sibari Basin, however, Nano and I have found little evidence of strike-slip faulting. Instead, what we’ve found are normal faults that are moving rocks near the surface through the doorway, while leaving deeper rocks behind. In this way, the crust acts more like a layered cake, in which the bottom layer remains in the doorway while the top slides through on a slippery layer of frosting. We need a lot more data before we know which mechanism is working. The fun part now is thinking of other ways that Calabria might slip through the doorway.
After the memorable trip up Mount Etna, Nano went to the Southern Apennines, while my parents and I made the familiar trip (for me, anyway) across the Sila and into the Crotone Basin. I raved to my parents about the great beaches and wonderful swimming in the Ionian Sea; I reminisced about my time on top of the Sila hiking through pine forests and the Switzerland-like lakes up there; I told them stories about the wonderful old towns nestled high on the rocks all over Southern Calabria. But when we arrived at the agriturismo, all they were interested in doing was getting up early, hopping in the car, and driving to outcrops to help me collect data.
Over the course of two days, we hunted down Upper Messinian conglomerates to help me and Nano with our research of the Messinian Salinity Crisis. My parents became master rock identifiers as we counted ratios of chert to granite clasts within each conglomerate. This information helps to determine the “provenance” of the deposit, or what kind of rocks the river eroded.
They also learned how to tell what direction the river was flowing in– a tricky task. We looked for imbricated clasts. These are clusters of thin, flat clasts (not round ones) that are pushed by the current until their flat side is facing upstream. We measured the direction that the clasts were stacked to determine which way the river was flowing. With these two pieces of information (clast provenance and current direction) from a number of outcrops around the area, we are able to recreate the Crotone Basin’s drainage flow.
My parents were struck by the tranquility of my field area. We passed through a few small towns on our first day working, but the second day we drove 50 kilometers and saw only fields, cows, and goats. What I really wanted to show my parents was the attitude of the people.
The sense of family and community in Southern Italy is overwhelming. The workers at the bar we went to in the morning remembered me from last year and gave my parents special treatment while we were there. The farmers we passed stopped their tractors and asked us about ourselves.
If you are not careful, you can be trapped in an hour-long conversation. People are more important than work here.
For dinner on our last night together, I took my parents to Canciumati. The family was excited to meet my parents. Mario, the patriarch, told them that when I was in Italy, he considered me his daughter. They served us four huge courses and sent my parents home with two bottles of wine. They had adopted me and, now, my parents into their family. It’s a hospitality that is indescribable, and the heart and soul of this place.
Boris and Alfio, geologists at Sicily’s National Institute of Geophyscis and Volcanology picked us up in their four-wheel drive jeeps. Etna is a stunning image. She rises 3,300 meters right from the seafloor, towering over the towns located around her flanks, providing fertile land for farming and beautiful hiking and skiing. Alfio calls her their “Sicilian Mother”: bountiful and beautiful, but able to flare up at a moments notice.
We drive up the base of Etna studying the lava flows visible on the road cuts. Lava from a 1690 eruption traveled 45 km to Catania, destroying much of the city, before pouring into the Ionian Sea. As we make our way up the lava gets younger: 1700s, 1983, 1991-2, until we finally reach the tourist center where lavas in 2001 and 2002 lavas destroyed several buildings. There is a cable car that takes people from the tourist camp to 2,500 meters. The cable car was first built in the 1970s so people could more easily reach the summit. Periodic lava flows have destroyed it four times in 40 years. The current one was rebuilt after the 2002 eruption.
At base camp, we stop to pick up Doug and Diane, two videographers accompanying us up the mountain. Boris and Alfio also grab a caffé (an Italian staple). We pass through the gates for authorized personnel only, getting annoyed looks from the tourists who have to pay to ride the cable car or trudge up themselves.
We’ve driven about halfway up, when we notice two large hills covered with ash towering over us. In 2000, the area was a flat expanse of ash without these features. Within a year, magma beneath Etna had generated these two massive cones.
Boris says that every time he comes up to Etna he takes dozens of photos and that in the seven years has accumulated hundreds of photos of features that are no longer part the landscape. We so often think of mountains as slowly growing features that may set off an earthquake every few decades, but rarely change within our lifetime. And here is Etna that, like all active volcanoes, changes completely every few years, even without a major eruption.
We park the jeeps around 2,800 meters and begin to hike across thick deposits of windblown ash. We can see traces of snow that fell this year or several years ago, preserved under the ash. The walking gets tough as the ground turns to lava called A’a (for its Hawaiian counterpart).
A’a is crumbly, sharp, and painful to grab onto if you lose your balance.
Further up we start to see rocks of hydrothermal origin. These are composed of minerals that crystallize from water heated inside Etna (sulfur is the most common mineral). We’re still far from Etna’s active caldera, so these are rocks that were ejected from the caldera during Etna’s numerous explosions, or burps as Nano calls them.
We make the last scramble across a 40 degree slope to edge of the Etna’s most active caldera, where enormous fountains of lava erupted in 2008.
Over a period of eight months, 66 lava fountains gushed into the air. (Compare this to Mauna Loa’s 46 lava fountains in three years.)
So here we are, standing right next to it.
The rocks are coated in soft ash from explosions earlier this year, in April. They are warm to the touch from the magma just beneath the surface. Walking around, we come across vents of hydrogen sulfide under our feet. If the breeze blows the wrong way for too long, the smell of rotten eggs is overwhelming, burning your eyes, nose, and throat. Boris said he’s breathed in so much hydrogen sulfide, he has destroyed much of his sense of smell.
The trek back down Etna is treacherous, but beautiful. It’s a relief to finally make it back to the soft ash and our jeeps. Those of us here for the first time – myself, my parents who are visiting from Massachusetts, Doug, and Diane are nearly speechless with awe and wonder.
The next morning Boris calls to tell us that the caldera edge we were hiking along had collapsed into the caldera. The powerful, scary Etna had changed the landscape once again. I agree with Alfio: a Sicilian Mother after all.
Italy has some of the most famous volcanoes in the world: Vesuvius, Stromboli, and Vulcano all lie in a chain along Italy’s western coast. Scientists have found that these volcanoes are all intricately linked to the subduction of the Ionian Sea beneath southern Italy, Calabria, and Sicily.
An oceanic plate contains rocks that have a lot of water in them (not surprisingly). This water is not just sitting in the pore space of sediments, but it is bound into the crystalline structure of the minerals that make up the oceanic crust, as water.
When the oceanic plate reaches depths of about 100 kilometers during subduction, temperatures and pressures become large enough that the water bound in the minerals becomes unstable and is released into the mantle. Water enters the mantle (where no water was before) and lowers the melting temperature of the mantle rocks, so small amounts of rock begin to melt where an oceanic plate is subducting.
This melt then rises through the crust and generates volcanoes at the surface.
These are known as subduction volcanoes, or arc volcanoes, and every active subduction zone has a chain of volcanoes generated by the addition of water to mantle. For example, in Japan, the Pacific Plate is subducting under Asia; in Chile, the Pacific Plate is subducting under the South American plate; and in the northwest United States, the Juan de Fuca Plate is subducting beneath the North American Plate (creating volcanoes like Mount St. Helens).
Although subduction volcanoes dominate Italy’s west coast, it’s largest and most active volcano is not related to subduction. Mount Etna is located in eastern Sicily and stands over three kilometers (11,000 feet) above the ocean. It is one of the most active volcanoes in the world, spewing ash, lava, and gas nearly as often as Mauna Loa in Hawai’I (which erupts, on average, every 3.5 years).
So how do scientists know that it is not an arc volcano, even though it is so close to a subduction zone?
The chemistry of the lavas.
Geochemists analyze the chemical make-up of lavas erupted all over the world to determine their origin. For example, magnesium and iron are found deep in the mantle while potassium and quartz are only found in the crust. Mount Etna’s lavas are rich in Magnesium and Iron, but also have a lot of potassium.
So where is the lava coming from? We are collaborating with geochemists at the National Institute of Geophysics and Volcanology (INGV) in Catania, Sicily to try to figure out just that. Tomorrow we climb up Mt. Etna to look at its most active caldera (responsible for lava flows in 2008 and explosions earlier this year) to learn about Etna’s history and talk about why this immense volcano is even there.
The glaciers around Puncak Jaya have long been in visible decline. From 1936 to 2006, they lost nearly 80 percent of their area–two-thirds of that since 1970, according to a new paper by glaciologist Michael Prentice of the Indiana Geological Survey, who has long been interested in the area. Satellite images show that from 2002 to 2006 alone, the remaining ice decreased from 2.326 square kilometers to 2.152–a 7.5 percent drop. Now, with researchers there, other signs have become obvious. Take a look at the pictures below of the Northwall Firn Glacier, about 2.5 kilometers from the summit of Puncak Jaya, taken by Paul Q. Warren, a geologist with the Freeport McMoRan company who has been helping plan and execute the ice-coring project since October 2008.
Maybe the most difficult thing about ice cores comes after the actual drilling: then you then have to get them out and transport them long distances, and make sure they don’t melt. Otherwise, all that work was for nothing. Here are some images showing how we handle them initially. (Courtesy David Christenson/Freeport McMoRan)
Here are some photos of the ice drilling, and the site where we are working. All come courtesy of David Christenson, Greg Chmura and Ario Samudro, the video/photography team from Freeport McMoRan, which has been helping us with all phases of logistics.