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Glacier Marks on Mount Chirripó

Sculpting Tropical Peaks - Wed, 07/09/2014 - 15:39

By Max Cunningham
June 12, 2014
We continued to sample boulders in Valle de Las Morrenas, Valle Talari, where the hostel sits, and several places along Mount Chirripó’s ridgeline.

Max 7.1

Large boulders of granodiorite line the ridge of Mount Chirripó. These are likely produced by exfoliation, a process that occurs in response to stress release associated with the melting of glacier ice.

The view from the top of Mount Chirripó is spectacular.  Looking out along the ridge I could see huge boulders of granodiorite produced by exfoliation, or the response of rock at the surface to the removal of ice.

Max 7.2

Striations in the meta-sandstone at the summit of Mount Chirripó point down the axis of Valle de Los Lagos, (a mechanical pencil and sample bag are included in the picture for scale, the pencil points in the direction of striations). Striae are a telltale sign of glacial coverage.

The actual summit of Chirripó, however, is a very different kind of rock.  I believe the peak is composed of a sedimentary rock that was melted and then fused back together as the magma that formed the granodiorite rocks moved toward the surface.  This metamorphosed sandstone (meta-sandstone) is extremely hard, and resistant to weathering processes.

In the meta-sandstone near the summit of Mount Chirripó, I discovered glacial striations.  These striations occur at 12,513 feet (the summit is 12,529 feet), which is a good 1,000 feet above the moraines in the upper portion of Valle de Las Morrenas.

Back to Mount Chirripó

Sculpting Tropical Peaks - Tue, 07/08/2014 - 11:14

By Max Cunningham
June 11, 2014

 Volunteers  at the Cloudbridge Reserve stay in a series of houses built in the Costa Rican rainforest.   They work towards returning mountainsides near Mount Chirripó to natural conditions.

Volunteers at the Cloudbridge Reserve are returning the hills near Mount Chirripó to natural conditions.

Mike and I hiked down 7,000 feet from Mount Chirripó to the Cloudbridge
Reserve early on the morning of June 10th to refuel and replenish supplies.

At this point, the Cloudbridge Reserve deserves a special mention.  Tucked away in the forest above San Gerardo de Rivas, volunteers at the Cloudbridge Reserve work to transform old farmland into natural forest.  After the cold ruggedness of the Mount Chirripó summit, the volunteers at Cloudbridge provided an exceptionally welcoming and engaging environment.  Mike and I were extremely lucky to have such a supportive base camp.

I kept an eye out for interesting geomorphology as I walked along the trails of the Cloudbridge Reserve.  The rivers here are particularly beautiful.  The water is clear and blue, and channel beds are floored by bedrock and boulders (all granodioritic in composition, like many of the rocks atop Mount Chirripó).  I was struck by the power of the local rivers; the erosional features carved into this hard, granodioritic rock were impressive.

The raging Chirripó River cuts through granodiorite, about 1 mile away from the Cloudbridge Reserve.

The raging Chirripó River cuts through granodiorite, about 1 mile away from the Cloudbridge Reserve.

After two days of rest and catching up on all we’d missed while isolated on Costa Rica’s highest peak, Mike and I headed back up to Mount Chirripó to continue sampling and to learn more about the processes shaping this landscape.

During our second journey, we hoped to extend our sampling range by venturing farther into glacial valleys and higher onto peaks.  We targeted Valle de Las Morrenas, a valley that we knew well from our first sampling trip and that other researchers had discussed extensively.

Earlier, we sampled boulders from moraines adjacent to large lakes.  This time, we targeted a steep drop-off (what we called a “lip) that occurs in the valley directly below the lakes.  Looking at maps and satellite images, it appeared that the lower valley was actually a remnant cirque:

A 60-foot drop-off separates the upper and lower valleys in this picture.  The lip may represent the retreat of a large glacier that once filled lower Valle de Las Morrenas.

A 60-foot drop-off separates the upper and lower valleys in this picture. The lip may represent the retreat of a large glacier that once filled lower Valle de Las Morrenas.

Our discovery of a large lateral moraine in the lower valley corroborated our hypothesis that a glacier produced the pronounced lip in Valle de Las Morrenas.  The vegetative cover increased substantially as we moved lower in the valley, which made accessing the moraine a real challenge.  After pushing through thick, woody bushes, we finally found ourselves on the crest of the moraine.

From the image it’s hard to tell, but this is actually a pretty big moraine, Max 6.4about 50-60 feet in height.  Meandering rivers cut through cobbles along the moraine’s edge, analogous to what we saw in Sabana de los Leones, only here with water raging through the channel.

Max 6.5We quickly came to realize that the boulder selection on the crest of this lower moraine was a far cry from the beautiful, large, flat boulders we saw along moraines in the upper valley.  Here, boulders seemed to be more deeply weathered, and more sparsely scattered.

While the lack of good boulders for sampling induced a bit of hand wringing (made worse by storm clouds quickly moving up the valley), the effectiveness of weathering on these boulders may add to the story of glaciation at Mount Chirripó.  Deep weathering of boulders suggests that they have been sitting around, exposed to the atmosphere, for a long time.  How long?  Glaciologists have employed relative weathering techniques for centuries to estimate exposure age, but 10-Be dating will tell us for sure.

 

 

Australopithecene Dental Calculus

Geopoetry - Fri, 06/27/2014 - 09:36
 AG Henry, Nature, 2012.

Phytoliths — mineral particles formed by plants — found in the teeth of one of our ancient ancestors. Photo: AG Henry, Nature, 2012.

Across a mixed landscape, Au. sediba plods
Sometimes on two feet, and sometimes on four,
Munching on fruits and leguminous pods,
Nuts and some seeds … C3 foods galore!
They did have a choice (so coprolites hint);
Lush grasses, fat grazers were also around,
But in these old ancestors (destined for flint?)
New clues, new stories have just now been found.
With lasers and microscopes, old dental plaque –
Tiny, stuck phytoliths show a rich diet!
Scratched-up enamel, it all brings us back
To lives of these creatures that have long been quiet.
What wonders are learned from plaque and from feces,
History bound in compounds beneath!
So, we should say to that wonderful species:
Thanks for not brushing your teeth!

___________________________________________

Further reading:

Palaeoanthropology: The ancestral dinner table, Nature, 2012

The diet of Australopithecus sediba, Amanda G. Henry et al., Nature, 2012

This is one in a series of poems written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory

Dancing in the Darkness

Geopoetry - Fri, 06/20/2014 - 08:59
Hatchet fish, approximately 3 cm long (photo taken by Adelaide Rhodes and Jarrod Scott)

Hatchet fish, approximately 3 cm long (photo taken by Adelaide Rhodes and Jarrod Scott)

 

In deep darkness, cunning lights are softly luring prey,

Drawing closer to the glow, only some will flee …

Subtle bodies, clear as glass, with organs on display,

Exquisite dances only certain piercing eyes can see.

Worm-like creatures undulate, jaws hang wide and gaping,

Iridescent, jeweled young ‘tween lurking hunters skitter.

The deadly art of eating faces that of death escaping,

From afar, a dazzling show, a many-legged glitter.

Armored, silver-plated, soft as jello, far from shore,

Seeking wonder, terror, treasure, out here I will be.

Stranger than the strangest film on aliens at war:

The scintillating, gorgeous sight of plankton in the sea.

 

_____________________________________________

Further reading:

UNOLS Chief Scientist Training Cruise, “See Monsters Here”

UNOLS Chief Scientist Training Cruise, “Microscopic Zoo”

This poem was inspired by time spent on a UNOLS Chief Scientist Training Cruise (Barbados to Bermuda, June 2014).

 

This is one in a series of poems written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory

Herbie’s Great Adventure: NUM Dendroecological Fieldweek

Kristen de Graauw and Cari Leland

Cari and Kristen here, checking in from Mongolia. This year we were invited to be instructors for the Third National Dendroecological Fieldweek, May 23-29 in Udleg, Mongolia. We arrived to Ulaanbaatar on May 20th so we were fortunate enough to have a few days to recover from some pretty terrible jetlag before beginning the fieldweek marathon. Anyone who has ever attended a fieldweek anywhere in the world knows how challenging (and rewarding!) these events can be. Our first few days of the fieldweek were spent at the NUM (National University of Mongolia) research station near Udleg, a few hours north of UB. We were so happy to see the beautiful countryside for a few days. We got to ride there in this awesome Russian vehicle, which Cari nicknamed Herbie.

 

The roads were rough but Herbie was a trooper and we arrived at the research station safely.

The roads were rough but Herbie was a trooper and we arrived at the research station safely.

We took a break at Teacher’s Pass for a nice panoramic view of the mountains before continuing on to the research station.

We took a break at Teacher’s Pass for a nice panoramic view of the mountains before continuing on to the research station.

The research station was a complex of buildings for housing, a kitchen, and lecture rooms. We shared a cozy room for two and enjoyed beautiful views of the valley and mountains surrounding us.

The NUM Forestry research station

The NUM Forestry research station

Our room from the outside...

Our room from the outside…

..and the inside.

…and the inside (Hi Cari!).

After everyone settled in, we met for the opening ceremony. Baatar gave a nice introduction of the project and the history of the CEME collaboration. There were 8 students in total, and 7 of them were female (girl power!). There was a good mix of participants; from first year undergraduates to PhD students.

Baatar giving the opening ceremony speech.

Baatar giving the opening ceremony speech.

After the opening ceremony we went out to the field. Baatar gave us a guided tour of all the current research projects at the station (there were many!) and the potential sites for the fieldweek. Then we gave a quick lecture on the basics of dendrochronology and headed back towards the research station to discuss potential fieldweek projects.

The flux tower on the research station property. It was pretty impressive.

The flux tower on the research station property. It was pretty impressive.

We noticed Gypsy moth larvae emerging from their cocoons on the ground near the forest.

We noticed Gypsy moth larvae emerging from their cocoons on the ground near the forest.

More gypsy moth larvae after emerging from their cocoons.

More gypsy moth larvae after emerging from their cocoons.

We headed back after a nice hike through the forest.

We headed back after a nice hike through the forest.

Day 2 at the research station was field sampling day. Unfortunately we woke up to a cold and rainy day but that didn’t stop our groups from heading out into the forest. After a long discussion we decided Cari would teach the Climate group and Kristen would teach the Ecology group. Cari’s group headed up the mountain in search of old larch and pine trees to core while Kristen’s group went to a portion of the forest that had been logged. The goal for the climate group was to find moisture-stressed trees and look at the relationship between tree rings and climate. The ecology group’s goal was to determine logging dates and the effects on surviving trees.

Cari’s group preparing to core a large pine near the mountain ridge.

Cari’s group preparing to core a large pine near the mountain ridge.

Kristen’s group coring a living larch near the stump graveyard.

Sundermaa coring a living larch near the stump graveyard for Kristen’s ecology group.

After one of the coldest and rainiest field days we’ve ever experienced we headed back to the field station to thaw and dry ourselves and the cores.

Cari’s group heading back from the ridge.

Cari’s group heading back from the ridge.

While we waited for the cores to dry, the students practiced skeleton plotting.

The students mounting wet cores with tape to help them dry straight.

Margad, Togii, and Badra mounting wet cores with tape to help them dry straight.

Byamba teaching Oyunna a skeleton plotting exercise.

Byambaa teaching Oyunna a skeleton plotting exercise.

The students are working hard on their skeleton plot exercises, while Kristen and Cari check their work.

The students are working hard on their skeleton plot exercises!

Everyone was very anxious to see if their skeleton plots matched!

Everyone was very anxious to see if their skeleton plots matched!

After a rainy day, we were treated with a beautiful sunset.

After a rainy day, we were treated with a beautiful sunset.

The next day we mounted the cores with glue and taught the students how to sand. They quickly learned that a well sanded core took time, patience, and persistence. At the end of the day we headed back to UB to begin laboratory methods.

Sainaa sanding her first core.

Sainaa sanding her first core.

Kristen telling the students they need to sand more! “Sand more!!”

Kristen telling the students they need to sand more…“Sand more!!”

The view from our sanding “room”. Not bad!

The view from our sanding “room”. Not bad!

Back at the university we had to hit the ground running with lab methods. The students skeleton plotted the samples from the research station one day, learned how to do the list method and measure the next day, and finally on the last day they learned how to run COFECHA and read the output files. It was challenging but everyone worked their hardest. The final day was very busy. The students were working on their presentations until the very last minute. The groups did an outstanding job presenting their projects, which made us feel so grateful for being able to teach such a bright and dedicated group of students. During the closing ceremony Baatar gave us both a really nice Mongolian tree and shrub guide book and then presented each student with a certificate of achievement. The students then gave us the most thoughtful gifts of Mongolian art and script.

Oyunna discussing the correlations between climate and pine during the climate group presentation.

Oyunna discussing the correlations between climate and pine tree growth during the climate group presentation.

Baatar presenting Margad with her certificate of achievement.

Baatar presenting Margad with her certificate of achievement.

 Cari, Margad, Togii, Sundermaa, Oyunna, Sainaa, Gerelee, Baatar, Sanaa, Kristen, M?, Byambaa, and Badra.
The whole group after an amazing fieldweek! From the left: Cari Leland*, Margad Ovgonkhuu, Togtokhbayar Erdene-Ochir, Sundermaa Sergelen, Oyunmunkh Byambaa, Sainbayar Gombo, Oyungerel Sereenen, Baatarbileg Nachin*, Oyunsanaa Byambasuren*, Kristen de Graauw*, Myagmarsuren Batdorj, Byambagerel Suran*, and Badar-Uugan Khasbaatar. ( *Instructors)

 

 


Categories: TRL

A Quick Retreat from ‘Mountain Lion’ Savannah

Sculpting Tropical Peaks - Tue, 06/17/2014 - 11:03
Max 5.1

The discovery of a flat grassland leads to a morning of exploration.

By Max Cunningham
June 10, 2014

Mike, Colin and I made meticulous plans for exploring Mount Chirripó before we left New York, but on the way to the summit Mike and I saw something that made us change direction: at about 9,500 feet, a mysterious grassland beckoned beneath jagged peaks. With just one day to go before our trip back to the Cloudbridge Reserve to refuel, we decided to make an early morning trek to this unusual valley to investigate why it is so flat and devoid of vegetation.

Max 5.2

The dry stream bed is sharply cut but lined with angular rocks suggesting minimal erosion.

Over the course of a beautiful, sunny day Mike and I trekked over the rugged terrain from Crestones Base Camp before reaching a sudden transition from forest to grassland. A few things struck us. First, a thin river snakes through this entire shallow valley. Around bends in the river we noticed sharply cut banks where the stream has become more powerful and eroded away the banks.

Max 5.3

A stone marks the place where a lion killed someone in 1956.

Second, we were surprised to find the stream bed completely dry. From a distance, we had expected to find a powerful body of water. In another test of our geomorphology knowledge we discovered that this dry stream bed is paved mostly in cobble-sized rocks, the type you might find on a cobblestone street except these cobbles are sharp and angular instead of smooth and rounded. Mike and I spent the morning walking the Sabena de Leones valley and the more we looked, the more baffled we remained by the processes that shaped this landscape. Why is the river bed dry and its sediment load so large and angular? We hope to find more clues in the coming week.

In the early afternoon, Mike and I stumbled on a small marker along the river channel in Spanish dated 1956. Combining our Spanish skills, Mike and I deduced that the sign commemorated the unfortunate death of a man by mountain lion, and then I realized that Sabana de los Leones  translates to “Savannah of the Lions.” That’s all we needed to know before skedaddling back to the Talari Valley and the security of the Crestones Base Camp.

Landslide Up Close

Sculpting Tropical Peaks - Mon, 06/16/2014 - 11:31

By Max Cunningham
June 9, 2014

Max 4.1

The landslide below the dark rocks in the center of this photo was discovered first in satellite images.

During the last decade, scientists have noticed an apparent rise in catastrophic events in mountain valleys as glaciers retreat and permafrost thaws. Some evidence suggests that thawing glacial valleys are responsible for enormous, fast-moving landslides that can destabilize river dams and cause other damage. Last July, my colleague Colin Stark and others at Lamont identified one such landslide in Alaska.

The idea that catastrophic processes may become more frequent as glacial valleys warm globally is a frightening one, but further information is needed to assess the threat. I came to Mount Chirripó hoping to find evidence of past landslides. Before flying here, Stark and I used high-resolution satellite images to identify potential landslide features on Mount Chirripó. On our second day in the field, Kaplan and I tried to locate them on foot.

We found our first landslide in Valle de los Conejos, a cirque valley carved into Mount Chirripó’s southern side. Apparently, we walked right by it on our previous day of fieldwork; the trees and bushes growing amid the fallen boulders provide an excellent disguise.The glacial debris blends in almost perfectly with the hillside. To highlight it, I have outlined the scarp in red where the failure occurred, but even this image, taken more than a half-mile away, is deceiving. Mike and I spent what felt like hours whacking through thick bushes to get there. You can just make out some of the large boulders in the background.

Max 4.2

Kaplan bushwhacks to the landslide.

From a distance I thought we could scale the landslide, but the house-sized blocks were too big to scramble over.  During the slide, boulders stacked up on each other and formed crevasses and caves that are now covered in treacherous mats of vegetation. I suspect that pumas may sleep in the caves by day if they are able to withstand the altitude.

Mike and I traipsed around the landslide, stopping at various scarps to enjoy the views. The run-out distance appears to be only about a tenth of a mile, and the boulders are densely packed. Looking down, I got the impression that the landslide created a crevasse somewhere between 60 to 100 feet in depth. When did this major failure happen in relation to deglaciation?

Max 4.4

Quartz sampled from the landslide debris may help us discover when the event happened.

Mike and I decided to use our CRN dating tools to find out. We made our way to several boulders on the east side of the landslide, where the rock is sedimentary, unlike the granodiorite found in the Valle de las Morrenas.  Once again, Mike and I found bits of fine-grained quartz in the rocks, indicating we can measure their Beryllium-10 levels to understand how long this landslide has been exposed to cosmic rays. Mike and I think that the extent of weathering on these boulders is a clue to the age of the landslide: For the surface of these boulders to undergo alteration, they probably sat in the same place for a long period of time. Perhaps this landslide is indeed paraglacial, a result of glacier retreat and permafrost thaw. We hope our efforts to measure CRN production here will inform us.

Chiseling Away

Sculpting Tropical Peaks - Fri, 06/13/2014 - 09:52

By Max Cunningham
June 8

Max 3-4

Cunningham chisels away at this glacial moraine for a sample that will reveal when the ice last withdrew.

Our expedition has two main goals: assess glacial erosion features on Mount Chirripó and search for clues of the summit’s age. Were the broad, flat landscapes on Mount Chirripó formed by glacial erosion or a change in tectonic forces pushing the Talamanca Range up about 2.5 million years ago?

A chemical dating technique called Cosmogenic Radionuclide (CRN) Dating may lead us to the answer. This technique will help tell us how long ago the valleys flanking Mount Chirripó eroded, and therefore, whether Mount Chirripó’s high elevation landscape is older than 2.5 million years or whether it eroded into its current shape as recently as 10,000 years ago.

Earth is being constantly bombarded by high-energy protons and neutrons from beyond our solar system, and CRN dating exploits this process. The collision of high-energy particles and atoms in the atmosphere and on rock at Earth’s surface produces new atoms of different mass, or isotopes. Fortunately for many Earth scientists, the impact of cosmic rays and oxygen produces an extremely rare isotope of the element Beryllium: Beryllium-10.  Oxygen is abundant in Earth’s crust, and quartz (SiO2) is among the most common minerals found there. When cosmogenic rays react with quartz at the surface, about six atoms of Beryllium-10 are produced per gram of quartz per year.

Measuring concentrations of Berylium-10 at the surface can potentially tell us how long the rock has been exposed to the atmosphere, and quartz is a particularly convenient mineral for measuring Beryllium-10 concentrations. Mike and I sought out glacial features with quartz-bearing rocks at Mount Chirripó with the hope of understanding whether rocks here were exposed to the atmosphere after the recent retreat of ice.

Max  3-1

Glacial debris can create natural dams where lakes form.

Glacial features jumped out at us during our initial tour of Mount Chirripó. We saw broad cirque valleys, floored by large lakes likely filled during glacial retreat. We also saw striated rocks and moraine ridges scattered with cobbles and boulders. In one valley, Valle de Las Morrenas, we noticed several lakes above the boulder-strewn ridges. This fits in neatly with previous observations of lakes dammed by moraines.

Max 3-2

Kaplan inspects a moraine.

Because moraines are abandoned when the ice retreats, measuring concentrations of Beryllium-10 in boulders on top of moraines may give us an idea of how long ago glacial erosion happened here. After locating boulders sitting on moraines, our next step was to see what the boulders are made of.

 

Max 3-3

Chiseling exposes a fresh surface of quartz.

We discovered that many are granodioritic, an intrusive igneous rock composed of the minerals plagioclase, amphibole and our good friend quartz! Next we took samples to analyze their Beryllium-10 levels in the lab later. Collecting samples is a physically rigorous process, especially in the low-oxygen, rainy conditions at 10,000 feet on Mount Chirripó. With a hammer and a chisel, and a bandanna to protect our faces from shattering rock fragments, we chipped away at the surface of the boulder, hoping to come away with about two pounds of rock to analyze.

We collected samples from boulders on two moraine crests. After months of processing, we hope to be able to describe how long ago glacial ice retreated from different parts of the valley. Calling the day a success, we hiked back through the afternoon rain to Crestones Base Camp.

 

Apophis

Geopoetry - Fri, 06/13/2014 - 07:57
 BBC World Service

Images of Apophis from BBC World Service

You may have heard the recent cries:
An asteroid towards us flies!
Apophis, a rocky mass,
Some years from now will closely pass,
Into the “keyhole,” if she falls,
The president will get some calls.
Chances that this fate arrive?
0.000005

_______________________________

Further reading:

Apophis asteroid: Large space rock flies past Earth, BBC News, Jan. 9, 2013

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory. “Lake Goo Clue” first appeared on Allen’s website on Jan. 11, 2013.

Climbing Mount Chirripó

Sculpting Tropical Peaks - Thu, 06/12/2014 - 14:09

By Max Cunningham
June 7

After arriving in the town of San Gerrardo de Rivas, Mike Kaplan and I immediately started gearing up for our trek to Mount Chirripó.

Our arrival here was somewhat hectic. After landing in San Jose around 10:30 a.m., we hopped a bus to San Isidro de el General, a town just west of Chirripó National Park.  Winding through the rugged mountains of the Talamanca Range, we were treated to spectacular views of central Costa Rica’s countryside. Max 2a

Once in San Isidro de el General, we navigated our way to the local office of Ministerio de Ambiente y Energia de Costa Rica, the government agency that provides research permits for Chirripó National Park. Our contact, Marisol Rodríguez Pacheco, showed remarkable patience with our broken Spanish and helped us pull together some final requirements for the permit.

By 5 p.m., the two of us made base camp at the Cloudbridge Reserve, above the San Gerrardo de Rivas. Founded in 2002, the Cloudbridge Reserve supports researchers in Costa Rica and works towards sustainable forest management. Volunteers at the Cloudbridge Reserve provided us with a beautiful working space and a warm place to sleep.

Max 2-1

The clouds rolled in early, by 9 a.m., on their way from San Isidro de el General in the distance.

The weather here can be erratic.  During the early morning hours the sun is intense and the sky is blue; by 1 p.m. clouds roll in. You can anticipate heavy rain from 4 to 6 every day, and nights are cold.

After taking a day to gather food supplies and find porters to help us carry heavy packs up to Mount Chirripó, Mike and I set off around 4:30 a.m. to make our way to the top of Mount Chirripó before the afternoon rain.

Travelers and locals alike warned us that the hike would be strenuous, and indeed they were correct. The trail leading to Mount Chirripó is steep and rugged (although pristinely maintained), and we gained nearly 5,000 feet in elevation over nine miles of trail.

The trail leading up to Mount Chirripó around 8,000 feet is densely vegetated and humid.

The trail leading up to Mount Chirripó around 8,000 feet is densely vegetated and humid.

One especially difficult aspect of our climb was the dramatic change in climate with elevation. Below 10,000 feet, we trekked through a humid, dense rain forest, but once above about 9,500 feet, the vegetation became sparse and the temperature dropped. At the summit of Chirripó, we rarely experienced temperatures warmer than 60°F.

In terms of Earth surface processes, this dramatic change in environment invokes thoughts about difference in landscape evolution: How does change in altitude, and associated changes in climate, affect erosion processes in the long term? This is just one question we hope our research can eventually inform.

Above 10,000 feet, the climate is extremely different, and so is the terrain.  At high elevations we see broad U-shaped valleys, and cold conditions inhibit dense vegetation growth.

Above 10,000 feet, the climate is extremely different, and so is the terrain. At high elevations we see broad U-shaped valleys, and cold conditions inhibit dense vegetation growth.

After an 8.5 hour hike, we finally reached Talari Valley, a lowland about 500 feet below Mount Chirripó. We made camp at the Crestones Base Camp, a meticulously maintained hostel in the Talari Valley, near Cerro Chirripó. The Crestones Base Camp is home to many travelers seeking the thrill of climbing Mount Chirripó. Impressively, many of the hikers we encountered wake up around 2:30 a.m. to hike the remaining 5,000 feet to the peak of Cerro Chirripo to watch the sunrise over this beautiful mountain. Mike and I made no such plans, and instead rested for a busy week of fieldwork.

Max 2-5

From Crestones Base Camp, you can pick out our hostel with the green roof in this expansive view of Talari Valley.

 

Mount Chirripó: Shaped by Glaciers or Tectonic Forces?

Sculpting Tropical Peaks - Fri, 06/06/2014 - 13:38

By Max Cunningham

Max Cunningham

Max Cunningham

I’m a graduate student at the Lamont-Doherty Earth Observatory and work in Colin Stark’s Earth Surface Processes Group. My research focuses on the role that climate plays in molding Earth’s surface, and how we can use clues carved into landscapes to learn more about climate and climate change in the past.

Since arriving at Lamont-Doherty, I’ve focused my attention on glacial valleys responding to climate change. I want to learn more about erosion in landscapes undergoing a transition from cold, frozen conditions to warm conditions. Questions about the timing of glacial retreat in the past and the erosional processes that occur as landscapes unfreeze are particularly relevant today, as glaciers around the world shrink in response to a warming global climate. max 1

Specifically, I want to learn about the history of glacial erosion in tropical mountains. Features on many tropical peaks around the world suggest that glaciers once persisted at low latitudes, but nearly all of these places are far too warm to sustain glaciers today.

Google Earth images of glacial thumbprints at Mount Chirripo, Costa Rica (left) and Mount Wilhelm, Papua New Guinea (right).  Both mountains are located within 10° latitude of the equator.

Google Earth images of glacial thumbprints at Mount Chirripo, Costa Rica (left) and Mount Wilhelm, Papua New Guinea (right). Both mountains are located within 10° latitude of the equator.

Glaciers are a crucial link between climate and erosion: They form only under very specific climatic conditions and leave very distinctive marks after they retreat. During a glacier’s lifetime, snow accumulates at high elevation and compacts into hard ice that flows downslope; at lower elevations warmer temperatures melt away layers of snow, allowing ice deeper within the glacier to move toward the surface. The total effect of compacting ice above and disappearing ice below is a “scooping” motion, and rocks caught in this “ice scoop” wear away bedrock. A combination of this rock-on-rock wear and other processes produces features unique to glacial erosion, such as circular valleys called cirques. In map view glacially sculpted valleys look like thumbprints in clay.

A somewhat startling realization is that these glacial thumbprints can be found on mountains in hot, tropical places like Costa Rica, Uganda, Kenya and Papua New Guinea. Some major questions arise: How long ago did glaciers carve out valleys in the tropics? How far down mountainsides did glaciers persist in these perennially warm regions? To start honing in on these questions, I’ll be traveling to Costa Rica’s tallest peak, Mount Chirripó, in Chirripó National Park for the month of June.

On Mount Chirripó, which rises to 12,530 feet, glacial thumbprints are clustered a few hundred feet below the summit. River profiles have a distinctive shape, exiting U-shaped valleys along gentle gradients and then breaking suddenly into a steep slope at about 6,500 feet. Waterfalls, or more technically “knickpoints,” form at this steep slope change.

Scientists have studied the unusual glacial thumbprints and clustering of knickpoints at Mount Chirripó. In 2000, researchers at the University of Tennessee identified a series of lakes that formed as a result of glacial erosion. They extracted sediment cores from the lakes and noticed a sharp transition from granular, glacially-produced sediment to organic material with depth in the core. Using 14C radiometric dating, they found that the transition occurred between 12,000 and 9,800 years ago.

Why is that important? Between 20,000 and 10,000 years ago the world was thawing out of an ice age. The 14C dates imply that glaciers persisted at about 12,000 feet at Mount Chirripó as recently as 9,800 years ago. By comparison, North America’s Laurentide ice sheet, which once extended south of New York City, retreated into Canada well before 9,800 years ago.

A 2012 study looked at Mount Chirripó from a different lens. The collision of tectonic plates in the tropical Pacific Ocean pushed Mount Chirripó to its modern elevation, but the timing of this uplift remains unclear. The 2012 study suggested that the clustering of knickpoints could reveal when tectonic uplift began.

Rapid tectonic uplift provides rivers with potential energy that expresses itself in steep slopes that slowly creep up mountainsides, creating a “wave” of erosion that travels up hillslopes. By assuming a “vertical” erosion rate, these researchers estimate that knickpoints at 6,500 feet signify tectonic upheaval that began about 2 million years ago.

The conclusions reached by these independent studies present a major conflict. On the one hand, valleys atop Mount Chirripó may have been carved by glaciers. If this is the case, the landscape must be “young,” as glacial erosion would have occurred during the last 2.5 million years. On the other hand, the valleys at high elevations at Mount Chirripó may represent a landscape that existed before 2 million years ago and rode a pulse of uplift to 12,500 feet.

In other words, two competing hypotheses have emerged: Is Mount Chirripó a sculpture of glacial erosion, or an ancient landscape perched at high elevations by tectonic forces?

My colleague Mike Kaplan and I plan to analyze evidence of past glaciation on Mount Chirripó in an attempt to test these two competing hypotheses. Using a geochemical technique called surface exposure age dating, which will allow us to measure how long rocks at the summit of Mount Chirripó have been exposed to the atmosphere, we will attempt to test how “old” the landscape is—is it relatively young, around 9,800 years old? Or does it predate a massive shift in tectonic uplift that began 2 million years ago?

Lake Goo Clue

Geopoetry - Fri, 06/06/2014 - 11:53
Lake Tanganyika, Tanzania

Lake Tanganyika, Tanzania. Photo: K. Allen

The lands of Africa’s Horn,
Great Valleys sliced by a Rift,
By drought and famine are torn …
What drives such a large rainfall shift?
Detectives of lake muck and goo,
Through models and efforts terrific,
Put forth a paleo-clue
From the Indian, not the Pacific.

__________________________

Further reading:

Multidecadal variability in East African hydroclimate controlled by the Indian Ocean, Tierney et al. Nature 2013

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory. “Lake Goo Clue” first appeared on Allen’s website on Jan. 18, 2013.

Some Do Not Like It Hot

Geopoetry - Fri, 05/30/2014 - 13:35
 Sun et al. 2012, Science

Image: Sun et al. 2012, Science

The Great Dying, The Big One — The Permo-Triassic!
(In a time machine, not sure if that’s where I’d aim …)
As extinctions go, this one’s a blockbuster classic,
When most of Earth’s species dropped out of the game.
Conodont fossils reveal massive changes
In sea surface temperatures (and CO2?).
Terrestrial critters reduced their lat ranges;
Low-oxygen regions in deep ocean grew.
Peat swamps disappeared (a great gap in coal),
And at the equator, most fish would fry.
At times like these, seems wise to head for the pole!
In a hot-steamy world … adapt, move, or die.

_________________________________________

Further reading:

Lethally Hot Temperatures During the Early Triassic Greenhouse, Yadong Sun et al., Science, 2012

Life in the Early Triassic Ocean, David J. Bottjer, Science, 2012

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory. “Some Do Not Like It Hot” first appeared on Allen’s website on Oct. 19, 2012.

Clock Is Ticking in West Antarctic

Melting Glaciers-Tracking Their Path - Fri, 05/23/2014 - 11:54
Pine Island Glacier, Antarctica

The leading edge of the floating ice tongue of the Pine Island Glacier, Antarctica. Photo: M. Wolovick

Reports that a portion of the West Antarctic Ice Sheet has begun to irretrievably collapse, threatening a 4-foot rise in sea levels over the next couple of centuries, surged through the news media last week. But many are asking if even this dramatic news will alter the policy conversation over what to do about climate change.

Glaciers like the ones that were the focus of two new studies move at, well, a glacial pace. Researchers are used to contemplating changes that happen over many thousands of years.

This time, however, we’re talking hundreds of years, perhaps — something that can be understood in comparison to recent history, a timescale of several human generations. In that time, the papers’ authors suggest, melting ice could raise sea levels enough to inundate or at least threaten the shorelines where tens of millions of people live.

“The high-resolution records that we’re getting and the high-resolution models we’re able to make now are sort of moving the questions a little bit closer into human, understandable time frames,” said Kirsty Tinto, a researcher from Lamont-Doherty Earth Observatory who has spent a decade studying the Antarctic.

“We’re still not saying things are going to happen this year or next year. But it’s easier to grasp [a couple of hundred years] than the time scales we’re used to looking at.”

The authors of two papers published last week looked at a set of glaciers that slide down into the Amundsen Sea from a huge ice sheet in West Antarctica, which researchers for years have suspected may be nearing an “unstable” state that would lead to its collapse. The West Antarctic Ice Sheet is mostly grounded on land that is below sea level (the much larger ice sheet covering East Antarctica sits mostly on land above sea level).

Advances in radar and other scanning technologies have allowed researchers to build a detailed picture of the topography underlying these glaciers, and to better understand the dynamics of how the ice behaves. Where the forward, bottom edge of the ice meets the land is called the grounding line. Friction between the ice and the land holds back the glacier, slowing its progress to the ocean. Beyond that line, however, the ice floats on the sea surface, where it is exposed to warmer ocean water that melts and thins these shelves of ice. As the ice shelves thin and lose mass, they have less ability to hold back the glacier.

What researchers are finding now is that some of these enormous glaciers have become unhinged from the land – ice has melted back from earlier grounding lines and into deeper basins, losing its anchor on the bottom, exposing more ice to the warmer ocean water and accelerating the melting.

In their paper published in Geophysical Research Letters, Eric Rignot and colleagues from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory in Pasadena, Calif., described the “rapid retreat” of several major glaciers over the past two decades, including the Pine Island, Thwaites, Haynes, Smith and Kohler glaciers.

“We find no major bed obstacle upstream of the 2011 grounding lines that would prevent further retreat of the grounding lines farther south,” they write. “We conclude that this sector of West Antarctica is undergoing a marine ice sheet instability that will significantly contribute to sea level rise in decades to come.”

The region studied holds enough ice to raise sea levels by about 4 feet (Pine Island Glacier alone covers about 62,000 square miles, larger than Florida). If the whole West Antarctic Ice Sheet were to melt, it could raise the oceans about 16 feet.

 Eric Rignot

The glaciers studied by Rignot’s research team. Red indicates areas where flow speeds have increased over the past 40 years. The darker the color, the greater the increase. The increases in flow speeds extend hundreds of miles inland. Image: Eric Rignot

In the second paper, Ian Joughlin and colleagues from the University of Washington used models to investigate whether the Thwaites and Haynes glaciers, which together are a major contributor to sea level change, were indeed on their way to collapsing. “The simulations indicate that early-stage collapse has begun,” they said. How long that would take varies with different simulations – from 200 to 900 years.

“All of our simulations show it will retreat at less than a millimeter of sea level rise per year for a couple of hundred years, and then, boom, it just starts to really go,” Joughin said in a news release from the University of Washington.

Many scientists who’ve been studying the region were already braced for the storm.

“It’s gone over the tipping point, and there’s no coming back,” said Jim Cochran, another Lamont researcher with experience in the Antarctic. “This … confirms what we’ve been thinking for quite a while.”

Cochran is principal lead investigator for Columbia University in Ice Bridge, the NASA-directed program that sends scientists to Antarctica and Greenland to study ice sheets, ice shelves and sea ice using airborne surveys. Much of the data used in the new papers came from the Ice Bridge project.

Tinto, also an Ice Bridge veteran, agreed. “I thought it was pretty exciting, because we’ve all been working on this area for a long time, and that potential for the West Antarctic Ice Sheet to behave in this way, we’ve been aware of it for a long time,” she said. “[It] made me want to get in there and look at the rest of the area, what else is going on.”

And there are still many questions about what’s going on: How fast the ocean that swirls around Antarctica is warming, how those ocean currents shift, and to what extent that is influenced by global warming.

“I have a problem with the widespread implication (in the popular press) that the West Antarctic collapse can be attributed to anthropogenic climate change,” said Mike Wolovik, a graduate researcher at Lamont-Doherty who studies ice sheet dynamics. “The marine ice sheet instability is an inherent part of ice sheet dynamics that doesn’t require any human forcing to operate. When the papers say that collapse is underway, and likely to last for several hundred years, that’s a reasonable and plausible conclusion.”

But, he said, the link between CO2 levels and the loss of ice in West Antarctica “is pretty tenuous.” The upwelling of warmer waters that melt the ice has been tied to stronger westerly winds around Antarctica, which have been linked to a stronger air pressure difference between the polar latitudes and the mid-latitudes, which have in turn been linked to global warming.

“I’m not an atmospheric scientist, so I can’t evaluate the strength of all of those linkages,” Wolovik said. “However, it’s a lot of linkages.” And that leaves a lot of room for uncertainty about what’s actually causing the collapse of the glaciers, he said.

Researchers have been discussing the theory of how marine ice sheets become unstable for many years, said Stan Jacobs, an oceanographer at Lamont-Doherty who has studied ocean currents and their impact on ice shelves for several decades.

“Some of us are a bit wary of indications that substantial new ground has been broken” by the two new papers, Jacobs said. While ocean temperatures seem to be the main cause of the West Antarctic ice retreat, there’s a lot of variability in how heat is transported around the ocean in the region, and it’s unclear what’s driving that, he said. And, he’s skeptical that modeling the system at this point can accurately predict the timing of the ice’s retreat.

But, he added, “this is one more message indicating that a substantial sea level rise from continued melting of the West Antarctic Ice Sheet could occur in the foreseeable future. In the absence of serious near-term greenhouse gas mitigation efforts, such as an escalating tax on carbon, they may well be right.”

“It starts bringing it a little closer to home,” said Tinto. “It’s a significant amount of change, but something we can start planning for. Hopefully [this will] make people stop procrastinating and start planning for it.”

Cochran agreed: The papers’ message is “that … over the next couple hundred years, there’s going to be a significant rise in sea level, and at this point we can’t stop it.” But, he added, “it doesn’t say give up on trying to cut emissions. … [Just] don’t buy land in Florida.”

____________________________________________

For further details on what’s going on in West Antarctica, check out these resources:

The two papers in question:

Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011, E. Rignot, J. Mouginot, M. Morlighem, H. Seroussi, B. Scheuchl, Geophysical Research Letters (2014)

Marine Ice Sheet Collapse Potentially Underway for the Thwaites Glacier Basin, West Antarctica, Ian Joughin, Benjamin E. Smith, Brooke Medley, Science (2014)

Unexpected Sisters

Geopoetry - Fri, 05/23/2014 - 08:42
 BBC Photo Library.

An artist’s rendering of the extinct Elephant bird (Aepyornis maximus), which lived in Madagascar. Aepyornis stood over 3 meters tall. Image source: BBC Photo Library.

 

An ancient island’s trove of treasure: Madagascan fauna
Tenrec, fossa, lemur, hippo, dugong, bat, iguana.
A giant bird – O, wondrous beast! – a half a ton, and tall,
Laid foot-long eggs, had beefy legs, and did not fly at all.
Another ratite, far away within the South Pacific,
The kiwi! Shy, with furry feathers, appetite terrific.
Among the old-jawed birds, you wouldn’t guess that they’re close kin,
But DNA reveals a link from deep, deep down within.
If the kiwi’s closest kin is not its moa neighbor,
Drawing up the family tree might seem a puzzling labor.
The simplest answer blows the mind – it seems that they all flew
With wings they spread across the globe, and filled in niches new.
Dinos gone (darn asteroid) left lots of open spaces,
Birds came in, diversified, flew on an as-need basis.
From this, it seems that flightlessness evolved six separate times!
The song of life, though improvised, with patterns clear it chimes.

 

______________________________________________________

Further reading:

Ancient DNA reveals elephant birds and kiwi are sister taxa and clarifies ratite bird evolution, Mitchell et al., 2014, Science.

Little kiwi, huge extinct elephant bird were birds of a feather, Reuters

The Surprising Closest Relative of the Huge Elephant Birds, National Geographic

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory.

Weak Underbelly

Geopoetry - Fri, 05/16/2014 - 10:44
 New York Times.

A view of the West Antarctic Ice Sheet (Landsat). Source: New York Times.

 

Antarctica’s uncertain fuse,
A “weak underbelly,” said Hughes.
Pine Island and Thwaites,
Thrown open, the gates?
As humans, what path should we choose?

The East’s held strong millions of years,
Despite cries of wolf from some peers.
West into the sea,
Up one foot, or three?
Uncertainty some meet with sneers.

Below salty waves, ice is grounded …
In this case, we see fears are founded.
In our defense,
Some centuries hence,
I hope they’ll say reason resounded.

 

__________________________________________

Further reading:

Scientists Warn of Rising Oceans From Polar Melt, Justin Gillis and Kenneth Chang, New York Times.

Marine Ice Sheet Collapse Potentially Underway for the Thwaites Glacier Basin, West Antarctica, Joughin et al., 2014, Science.

Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011, Rignot et al., 2014, PNAS.

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory.

The New World

Geopoetry - Fri, 05/09/2014 - 09:24
Archaeological expedition in the Peruvian Andes (Kurt Rademaker, University of Maine at Orono).

Archaeological expedition in the Peruvian Andes (Kurt Rademaker, University of Maine at Orono).

 

On a man in the mountains, dusk falls;

Shadows seep upward and spread.

Scaling the black, chiseled walls,

He silently seeks the dead.

 

The Andes, sharp spine of Peru,

Shelter small secrets of stone.

That night, an ancient milieu:

Obsidian, jasper, bone.

 

Into deep history, peer:

Sharp edges of tools, human craft!

Adventurous people lived here,

Climbed, feasted, laughed.

 

Archaeological expedition in the Peruvian Andes (Kurt Rademaker, UMaine)

Archaeological expedition in the Peruvian Andes (Kurt Rademaker, UMaine)

 ____________________________________

Further reading:

Science-2014-Gibbons-567-8 (pdf)

“New Sites Bring the Earliest Americans Out of the Shadows,” Ann Gibbons, Science, 2014

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory

The Breathing Ocean

Geopoetry - Fri, 05/02/2014 - 10:10
 Jaccard et al. (2013) Science

Image: Jaccard et al. (2013) Science

Far south and farther south, where winds are cold and screaming,
Waters churn, and deep below, old sediments lie dreaming.
A million years’ residuum of life and death and dust,
A library of ice ages reposed upon Earth’s crust.
Very finely teased apart, this elemental tale,
On barium and opal deep into the past we sail.
With all the evidence aligned, a pattern brightly blazes:
Descent into an ice age world proceeds in two key phases.
An orchestra with many players ‘tween warm-cold inflecting;
Tiny cells, abyssal flow, great winds … now, who’s directing?

_________________________________________________

Further reading:

Two Modes of Change in Southern Ocean Productivity Over the Past Million Years, Jaccard, Hayes et al., Science, 2013

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory. “The Breathing Ocean” first appeared on Allen’s website on March 22, 2013.

Hell’s Chicken

Geopoetry - Fri, 04/25/2014 - 09:00
 Mark Klingler/Carnegie Museum of Natural History

The dinosaur Anzu wyliei. Illustration: Mark Klingler/Carnegie Museum of Natural History

From our great, wild west, those rusty, dusty hills,
Bones of a beast who would give a cowboy chills.
A fierce-looking crest – a mohawk made of bone!
Claws, beak, bony tail, locked within hard stone.
Heavy as a tiger, scary yet absurd;
Anzu, feathered giant: a dino, not-quite-bird.
Mysterious, its habits – egg-eaters? A chance.
But this terrifying creature may have also eaten plants.
We piece together dreams of the verdant late Cretaceous,
Shards, broken clues from the patient and tenacious.
How I wish I could’ve seen this dinosaur humungous;
I guess I’ll have to settle for their relatives among us!

______________________________________________

NVO

© Wikipedia:NVO

A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America, PLoS One, 3/19/14

Dinosaur dubbed ‘chicken from hell’ was armed and dangerous, The Guardian, 3/19/14

National Geographic, 3/19/14

Huffington Post, 3/19/14

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory. You can read more on Allen’s website.

Black Holes

Geopoetry - Fri, 04/18/2014 - 14:54
 SCIENCE VIDEOLAB

Image Credit: Science Videolab

In most observed galaxy hearts,
Massive black holes reside,
Formed from dark-baryon parts,
As huge stars collapse or collide.
Telescopes secrets divulge,
Hinting at coevolution,
The key: a galaxy’s bulge?
We do not yet know the solution.
Whence the crucial gas-fuel
With which to feed a black hole?
Do galaxies, holes often duel?
Or play a more symbiont role?
Next, we tackle all spectra;
Our tools, from low to high climb,
Sensing waves from far plectra,
Over the whole Hubble time.

__________________________________________

Further reading:

The Formation and Evolution of Massive Black Holes, M. Volonteri, Science, 2012

This is one in a series of poems based on science news, written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory. “Black Holes” first appeared on Allen’s website on Aug. 6, 2012.

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