From the Russian wilderness to the big city!

August 15th, 2014

Guest Blogger: Sarah Frederick (’15)

Arriving in Moscow was a sharp return to reality. Suddenly all of the things that had come to feel normal while we were in Kamchatka – the winding gravel roads and little towns with random meandering livestock that would peek in your windows – were replaced by traffic jams and the overwhelming immensity of the city!

Russia Blog Pics - 09One unique experience in Kamchatka was shopping. Shopping, like everything else in Russia is a very long, arduous process that takes hours longer than it should. Above is shown a typical store in Kamchatka. All of the goods are located behind the counter, so each item had to be individually requested from the shopkeeper. However, in all likelihood the first shop you visited would not have half of the items you required, so you would have to visit two or three additional establishments to find everything you needed. Even so, simple necessities like bread or beer were not always available. Also, take note of the high tech abacus being used!

The items we purchased were also completely foreign to me. While I was initially pretty skeptical, everything was quite tasty if you had an expert cook like Tatiana to prepare it!

Russia Blog Pics - 13Cow-in-a-can anyone? More commonly referred to as Tushonka.

Russia Blog Pics - 15There are a variety of culinary influences present. Lots of Uzbek cuisine, but we also encountered Georgian, Russian, and Ukrainian dishes. A common afternoon meal with borscht, beat soup of Ukranian origin, is pictured above.

While in Moscow we toured the Institute, a towering majestic building, one of seven built around the city, which houses several departments of Moscow State University, a museum, faculty and students.

Russia Blog Pics - 16An apartment in the wing to the right was actually our home for the duration of our visit.

 While in Moscow we of course visited the touristy section of the city.

DSCN2787The Kremlin

Russia Blog Pics - 17Dr. Wiles with our two hosts, Olga and Vladimir in front of St. Basils.

DSCN2794One of the prominent monuments on the Red Square is Lenin’s tomb. He has been on public display since shortly after his death in 1924.

Russia Blog Pics - 03One last picture from Kamchatka. Thanks for following us through our journey! We look forward to reporting on our findings from the lab soon!

Coring Across Kamchatka

August 12th, 2014

Guest Blogger: Sarah Frederick (’15)

After traversing every stretch of road within Kamchatka at least twice, 5 bear sitings, and becoming intimately familiar with Kamchatka mosquitoes (they come in three sizes!), we are on our way to Moscow. All in all we cored over 500 trees! So I am sure that everyone back in the lab can hardly wait for our return…

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Russia Blog Pics - 10Coring larch trees in the mountains of the Eastern Range.

Coring took us to every reach of the Kamchatka Peninsula. We made our way as far north as Ust-Kamchatsky, a port city that was strategically important during the Cold War when the entire peninsula was closed to nonresident Russians and foreigners alike. Then we drove all the way west to the Sea of Okhotsk before returning east to Petropavlovsk, a large port city on the Pacific.

During our travels we have explored a variety of environments. While the most pervasive by far was the taiga, swampy coniferous forests, we also appreciated the beauty of spring in the tundra.

Russia Blog Pics - 18Spring blossoms.

The devastation caused by the frequent volcanic eruptions was also evident. We frequently came across open ash fields and even pyroclastic flow deposits!

Russia Blog Pics - 08The desolate remains of a pyroclastic flow (fast moving current of hot gas and rock) produced by the adjacent volcano.

Besides collecting cores, we also learned a bit about the local culture and history. In Esso, we visited the museum where we learned about the traditional practices of the indigenous peoples and how they survived Kamchatka’s harsh climate.

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The main building of the museum exhibits the beautiful woodwork typical of the region.

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A reproduction of a traditional home of the Koryak people. In order to optimize heat retention, the structure is built partially underground and in the shape of an oven. It even has an escape hatch out of the top for when snow buries the structure.

Esso is also significant as the starting point of the Beringia, Kamchatka’s traditional dog sled race, which in the 1990s held the record for the longest dogsled race, rivaling Alaska’s Iditarod.

Back in Petropavlovsk we visited Kamchatka’s Institute of Volcanology and Seismology, scientists from which have most generously hosted and guided us on our journey. Along with several visiting Japanese geologists, we were given a tour of the museum of Volcanology. Here we learned about Kamchatka’s most active volcanoes and the work of the volcanologists in the region. They were most excited about a recent discovery of diamonds in the ash of the Tolbachik Volcano, which made me re-evaluate the goals of our expedition to that site. Had I known, I would have been far more interested in sifting through the sediment for diamonds than in the trees…

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Finally, for those have been asking about the bears. Here is a cutie that we came across on one of our last days in the field. These Kamchatka brown bears are very large, though not a big threat to humans, particularly in the summer when food is plentiful.

Volcanoes, Mosquitoes, and Bears, Oh My!

August 9th, 2014

Guest Blogger: Sarah Frederick (’15)

After three weeks in Russia it sure feels great to be back on US soil! Since we didn’t have internet access during this expedition, our blog posts come a bit delayed. Here is a bit about our first week in Kamchatka: If, like me, you have never played the board game Risk, you likely have never heard of Kamchatka. So to give you some context of where we are, below is a map of the North Pacific. As you can see, this peninsula, part of the Pacific Ring of Fire, is further east than Siberia and it is not far from Alaska. However, since flights between Alaska and Kamchatka are extremely limited, we were forced to fly the long way around. map

After our nearly 40hr journey, crossing 16 time zones, it was a relief to arrive in Petropavlovsk, Kamchatka.

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Above is a picture taken on top of an extinct volcano that overlooks the city. From L to R, Tatiana Kuderina (Senior Researcher at Moscow University), Sarah Frederick (’15), Vladimir Matskovsky (Researcher at Moscow University) and our lovely host Tatiana. This picture is an achievement, because as you will notice, it is the only picture in which all of the Russians are smiling!

eruption We were greeted in Kamchatka, the land of many mosquitoes, bears, and volcanoes, by scientists from the Volcanology Institute. And after a day of recovery we headed north into the great wild. While there have been no bear attacks, just three sitings so far, we were lucky enough to witness a small volcanic eruption during one of our expeditions!   Though described in the literature as ‘pristine’ and ‘untouched,’ over the past week we have found much of Kamchatka far from that with the forests along the single main road (unpaved dirt and gravel) having been clear cut. Even so, with a lot of help from our driver, Vasily, and his mighty passenger truck, we managed to locate old growth larch in the north. truck While our quest for trees has required us to spend extensive time in the swamps being devoured by millions of mosquitoes, we also made it to some of the more picturesque parts of Kamchatka as well. The highlight thus far was our trekup the Tolbachik volcanic complex where we were greeted by unseasonably clear weather. Not only could we see the majestic glacier topped volcanoes of the Eastern Range, but to the west, the towering volcanoes of the Median Range were also visible! tobal We are now heading south for our last few days of tree hunting. It is our hope that the tree ring data that we are collecting will help to connect the extensive network of tree ring chronologies developed for the Gulf of Alaska with those from the West Pacific. Helping to develop a better understanding of North Pacific climate.

A Wooster geologist’s summer research experience in The Bahamas: Sarah Bender (’15) and climate and sea level change over the past 6,000 years

August 20th, 2013

SB coverSarah Bender (’15) and Sarah Frederick (’15) had the opportunity this summer to complete National Science Foundation funded Research Experiences for Undergraduates (REUs). Each spent a good part of their summer completing a research project under the mentorship of accomplished and enthusiastic geologists. Sarah Bender (on the left above) worked under the mentorship of Dr. Lisa Park Boush (’88, center in the photo), a geology professor at the University of Akron, and Kristina Brady (’03, on the right), a curator at the University of Minnesota. A Wooster geology team! This is Sarah’s summer research story in her words and images. (Sarah Frederick’s story is in the previous post.)

This summer I had the pleasure of working with a group of seven interns and four mentors on Eleuthera Island, Bahamas and at the University of Minnesota Twin Cities and Duluth. For two weeks at the beginning of June, we cored three Bahamian lakes, two being blue holes and the other a coastal pond. The goal of this Research Experience for Undergraduates (REU) was to determine the anthropogenic changes that took place in the past thousands of years in the Bahamas by using proxy data from these lakes. The project was led by a Wooster graduate, Dr. Lisa Park Boush (’88), who like myself, was one of Dr. Mark Wilson’s advisees. One of the other mentors, Kristina Brady, also graduated from Wooster (2003) as Dr. Wiles’ advisee, and is now working at LacCore at the University of Minnesota as a curator.

My team worked on the first blue hole, which we named Duck Pond Blue Hole. Duck Pond Blue Hole is an inland circular body of brackish water located in the southern tip of Eleuthera Island. We hypothesize that there are underground conduits connecting the blue hole to the ocean due to the salinity and the fact that the water level was affected by tides. Cores were taken with hand-operated corers from three different spots along a transect of the lake. Overall, my team recovered over four meters of sediment from the three sites! We also took bathymetry data, depth profiles, and did a vegetation survey around the perimeter of Duck Pond Blue Hole.

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Myself, a teammate, and Kristina Brady (’03) capping a core from Duck Pond Blue Hole. Check out our mighty coring vessel!

The other team of interns worked on a coastal pond, located directly behind one of the most beautiful beaches in the world. They cored the pond at three sites and took similar lake profiling data as my team. They also worked on dune profiles with Dr. Ilya Buynevich from Temple University using his GPR machine.

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The other team of interns worked on a coastal pond, located directly behind one of the most beautiful beaches in the world. They cored the pond at three sites and took similar lake profiling data as my team. They also worked on dune profiles with Dr. Ilya Buynevich from Temple University using his GPR machine.

The rest of the time on Eleuthera was spent exploring the island and learning about its history. We took two day-long field trips in which we saw many geological features as well as archaeological sites. With the help of Dr. Perry Gnivecki and Dr. Mary Jane Berman, both from Miami University, we learned all about the native inhabitants of the Bahamas, the Lucayans. We hope our project will help them understand how they were affected by climate change and the landing of Columbus in 1492. Finally, we got to present our preliminary results to the people of the Bahamas at the Cape Eleuthera Institute.

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My teammates and I presenting Duck Pond Blue Hole at CEI.

After finishing fieldwork, we headed to LacCore, the National Lacustrine Core Repository, at the University of Minnesota in Minneapolis to analyze our data. We logged, split, photographed, and described our cores first. We also did a variety of lab work with core samples such as, carbon-14 dating, SEM, loss on ignition, making smear slides, and shell counts. We also got to work at the Large Lakes Observatory in Duluth, Minnesota using the XRF machine and doing grain size analysis.

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Myself and a teammate prepping samples for grain size analysis at the Large Lakes Observatory in Duluth.

This lab work took about six weeks to complete and we got some amazing results from it. We used the last few days in Minnesota to write our abstracts and make posters for upcoming conferences. Each person took one aspect of our project to focus on. My abstract and poster focuses on the mollusk communities of Duck Pond Blue Hole and how they may be an indicator for climate and sea level change in the Bahamas over the past 6,000 years.

In order to discover what we found, you will have to visit my teammates at GSA in Denver in October or AGU in San Francisco in December. I hope to be able to make it to the AGU conference to help present my team’s work, however, I won’t be presenting my individual abstract until the spring at a regional GSA meeting. If you want to read more on the project, check out the REU Bahamas page on Facebook or the daily blog we kept throughout the project. Now, it’s off to Byron Bay, Australia, for me! I hope everyone had a great summer and I wish you all a successful fall semester!

We must have walked 10 million miles.

July 16th, 2013

Guest Blogger: Abby VanLeuven

June 26th: Marble Mountain

Our arrival at the southern end of Marble Mountain begun with the sighting of 3 orcas that as Dr. Wiles explained were a sign of good luck. Thus began the assent into the bug-infested shrubbery complete with thickets of devils club and raspberry bushes. We were trying to climb to 2000 ft. elevation set up camp and then climb 400 more ft., in order to reach the Mountain Hemlocks that we were going to core. We were trying to core these particular hemlocks -because they are part of a Nunatak forest. A nunatak forest is an island of forest that survived the ice sheet moving over the area because of its high elevation. These trees would have been great for my thesis because of their age and high elevation.

About an hour into our hike the sun was bearing down on us, it was 85 degrees out and we were out of water with no streams or snow melt in sight. As the elevation and incline rose so did our levels of dehydration, frustration and exhaustion and around hour 5 we made the executive decision to turn around. Although it was pretty disappointing not to be able to reach the trees we ultimately made the right decision because of the lack of snow melt. Two hours later after sliding, stumbling, and falling down the mountain all while dreaming about water we heard the sound of the river and stumbled into it chugging as much as we could.

It was quite the adventure and although we looked it in the eye, Marble Mountain still holds its mysteries.

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Marble Mountain is the peak on the far left.

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Andy and Dr. Wiles trying to climb up the limestone rock face with 30 pound backpacks (our only break from dense Devils club and other shrubbery).

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Distressed after descending Marble Mountain (10PM).

June 28th-30th: days after Marble Mountain

We were rescued from Marble a day early and decided to take some cores from excursion ridge. We cored Western Hemlock, Mountain Hemlock and lots of Shore Pine. Although Shore Pines can sometimes be hard to correlate well, they have recently been in decline for a variety of biotic reasons and we are going to see if there is any climate signal that can be related to their stress.

The first day back (28th) we went up to Yellowleg trail, a lower site on excursion ridge, and started coring Western Hemlock and some Shore Pine. The lower elevation part of the trail started out dominantly a Western Hemlock forest opening up to more Mountain Hemlock and then ending with a bog full of Shore Pine. At the end of the day we were hiking along the road and saw a quartz vein that had been folded ductilely, which was really cool to see after learning about in structure.

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View at the base of the Yellowlegs trail overlooking Bartlett cove bay and Pleasant Island.

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Western Hemlock

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Quartz Vein.

Our next two days we started coring more Shore Pines in the valley below Excursion Ridge and finished coring the Yellowlegs Trail. While coring the trees in the valley we encountered our first rainy day but we survived. These Shore Pines are younger than the ones we sampled the day before but hopefully they will still yield valuable data.

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Bog at the top of the Yellowlegs trail.

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Coring a Shore Pine at the Yellowlegs trail bog.

To end our time in Gustavus we were invited by the foresters to aid them in their rivalry softball game against the lodge. We were acting as cheerleaders to the game, until the 5th inning where, in only 2 innings Andy got a run, Jesse made a diving catch at shortstop, and then Andy, as catcher, proceeded to drop the throw to home plate that would have prevented the lodge from winning. We met some great people and were sad to leave but at the end of the game with Andy’s huge mistake it was probably for the best that we were leaving on the ferry the next day.

On Saturday we took the ferry back to Juneau and there our adventure ended with a flight back to the lower 48 the next morning. We looked it in the eye and what an adventure Alaska has been.

1013659_10151677318583675_749107785_nTeam Alaska on a rainy day at the gateway to Glacier Bay National Park and Preserve.

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Team Alaska on a sunny day riding the ferry from Gustavus to Juneau.

We looked it in the eye

July 15th, 2013

Guest Blogger: Andy Nash

Gustavus, AK. June 25, 2013 – As our research trip to Glacier Bay National Park and Preserve winds down we have some time to reconnect with the world and share some stories from our trip. The first half of our trip in the park was spent in Wachusett Inlet sampling logs and stumps that were killed during the advance of glaciers. Our group of Dr. Wiles, Jesse Wiles, Abby Vanlueven, and myself set up camp on June 19th on the south side of the inlet as close to Carroll Glacier as we could get. Our camp was next to an alluvial fan, which had a stream fed by snow melt running through it. This camp made the perfect home for our 5 day stay. We were lucky to get great weather our entire stay in Wachusett Inlet. The temperature ranged from 70-80° F and it only rained once at night while we were in Wachusett.

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Our base map with daily tracks that show everywhere we hiked

Day 1

After camp was set up on day one the group kayaked and took a hike Northwest of the inlet and onto moraines formed recently by Carroll Glacier. This served as a way for us to get acclimated to the area and also to scout out potential sites for further investigation. On this hike we saw plenty of bear sign and moose activity but unfortunately we didn’t see either of the animals during our stay in Wachusett.

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Our group: Abby Vanlueven ’14, Andy Nash ’14, Jesse Wiles (left to right) standing on Carroll Glacier’s ice-cored moraines

Day 2

On day two we sampled logs on the outwash plain to the north of Wachusett Inlet. This outwash comes from Cushing and Burroughs Glacier which are located north of Wachusett and Carroll Glacier. I described the stratigraphy of this valley cut by outwash as well as collecting core samples from detridal logs. As we hiked around this outwash plane we came across some birds that were not pleased with how close we were to their nests. They were relentless in protecting their eggs, swooping in from all angles and diving right at our heads. They only stopped when we retreated back to our kayaks. We finished off our day by running up two valleys on either side of the inlet to see if the river had eroded away any sub-fossil wood.

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The valley north of Wachusett Inlet which was once the site of an ice dammed lake (1960s) and is now being cut down by glacial outwash streams

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Coring a log in the valley

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Our group’s typical reaction to bird attacks

Day 3

Day three of our Wachusett Inlet adventure might be the most painful day for me to recount. I don’t think I will ever forget June 21, 2013. We didn’t realize until after that our longest day also coincided with the summer solstice. One this day we hiked from Wachusett Inlet to Queen Inlet by crossing over the glacial moraines we hiked up on day one. What was different on this day was the discovery that some of these glacial features had remnant ice under their slopes. This made for some interesting scrambles up slippery sand covered ice slopes, lots of frustration, and assistance from the ice ax. We estimated that after 6 hours and about 9 miles of tough hiking, we finally reached Queen Inlet. The outwash plane was massive, about 1 mile wide and 2 miles long. For all of that work we were rewarded with cores from 4 samples. Luckily the great views and feeling of invincibility we got after completing that hike overcame the soreness and fatigue when we woke up the next day.

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One of the two naps we took in Queen Inlet

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Searching for logs to sample

Day 4

After our expedition the previous day we all agreed that day four would be a recovery day. We took a little paddle down the inlet to core logs brought down to alluvial fans by streams much like the one we camped at. Today ended up being our most productive day. In total we sampled over 25 trees and took more than 40 cores. We called it an early day and went back to camp to play some cards which proved difficult with the wind and the bugs.

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Abby and I extracting cores from a hemlock log

Day 5

Our final full day in Wachusett Inlet was dedicating to cover the last bit of ground that we hadn’t covered in the previous four days. We hiked back up to the moraines but turned north away from Queen Inlet (Thankfully). Our attempt was to go back to the outwash plain from day two and sample from the western side which was blocked off by a river. We soon learned that out effort were all for not as another outwash river came off of Carroll Glacier creating a wedge of inaccessible land between the two rivers. This was disappointing because I had hoped to describe the stratigraphy of this valley wall which was exposed a little bit better than the other side.

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Nobody was safe from the mud on our last day. Abby had a tough time not getting stuck

 

We decided that the only motto that was appropriate for our trip to Wachusett Inlet was, “We looked it in the eye.” We covered every area at the head of Wachusett Inlet where sub-fossil logs could have been found. Our adventure in Wachusett might have come to an end but we still have more to report on as we spend some time on Marble Mountain and in Gustavus with plans to core living trees now. Be sure to watch for the next post from Abby about our further travels in Alaska.

Dr. Michael Mann visits Wooster

March 28th, 2013

MichaelMann032713WOOSTER, OHIO–We were honored this week when Dr. Michael E. Mann, one of the world’s foremost climate-change experts and a leader in the efforts to educate the public about anthropogenic effects on the atmosphere, came to Wooster as part of our Richard G. Osgood, Jr., Memorial Lecture series. He gave a public lecture in the nearly-full Gault Recital Hall Wednesday evening (“The Hockey Stick and the Climate Wars: Dispatches from the Front Lines”), and then a Geology Club lecture the next day in Scovel (“The Past as Prologue: Learning from the Climate Changes in Past Centuries”). Students, faculty and staff of the Geology Department also had a wonderfully informative dinner with him in the Wooster Inn.

Michael Mann is very well known in the diverse community that studies climate change in the past, present and future. He was the senior author of a pivotal article in the Intergovernmental Panel on Climate Change (IPCC) Third Scientific Assessment Report in 2001. It set the direction for more than a decade of later climate research. He has written dozens of other papers and two books on climate change. He has received numerous awards, most recently the Hans Oeschger Medal of the European Geosciences Union.

The public Osgood lecture Dr. Mann presented on Wednesday was centered on his latest book. He described the recent scientific history of climate change research and then how he became an “accidental public figure” through the famous “Climategate” theft and publication of private email messages. His stories of attempted congressional interference in his work and that of other climate scientists were astonishing, representing what he calls “the scientization of politics” (where science — or pseudoscience — is used as a political tool).

The image at the top of the page is Dr. Mann near the end of his Osgood Lecture. The image on the screen is of his daughter enjoying a moment in the polar bear pool at the Pittsburgh Zoo and PPG Aquarium. He fears that someday such animals will be found only in zoos because humans “melted their Arctic environment.” Numerous questions and conversations followed.
MannLecture032813Dr. Mann gave a Geology Club presentation this morning in Scovel Hall on some of his scientific work (shown above). He talked about using proxies to model historical climate change and then predict future climate.
WilesMann032813For me one of the best moments was his conversation with Greg Wiles in our dendrochronology lab (above). It was great fun to see how the work of Wooster Geologists is part of the unfolding grand story of what factors control our climate, and why such research is critical in our efforts to cope with future changes.

A Tale of Two Museums: Part 1 — The Cleveland Museum of Natural History

December 6th, 2011

Last week I had the marvelous opportunity to visit two very different museums with Wooster Geologists. This is the first of two posts with short vignettes of the memorable sights and sounds.

The first museum was the Cleveland Museum of Natural History. Greg Wiles and his Climate Change class invited me to accompany them to see the visiting climate change exhibit. It was an excellent display of the latest ideas about changing climates, including accurate accounts of the evidence, controversies and possible solutions to the problem of anthropogenic global warming and its associated troubles. It was a pleasure to see this presentation with Greg because of his deep and very current knowledge of the science and politics.

Since the above links give plenty of information about the museum and climate change exhibit, I’ll just highlight two features in front of the museum I found very interesting:

The large sundial above represents the history of life by geological periods. Note the beautiful ammonite fossil model as part of the gnomon (the portion that casts the shadow).

Each segment of the horizontal portion of the sundial is a geological period. Can you tell which periods are shown here?

Finally, I think this sculpture in the front garden entitled “Venus From The Ice Field” by Charles Herndon is ingenious. It is carved from a granite boulder found in the local glacial till.

My next post will be about the second museum — a very different place!

Wooster’s Fossils of the Week: Sponge and clam borings that revealed an ancient climate event (Upper Pleistocene of The Bahamas)

September 11th, 2011

This week’s fossils celebrate the publication today of a paper in Nature Geoscience that has been 20 years in the making. The title is: “Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas coral”, and the senior author is the geochronological wizard Bill Thompson (Woods Hole Oceanographic Institution). The junior authors are my Smith College geologist friends Al Curran and Brian White and me.

The paper’s thesis is best told with an explanation of this 2006 image:
This photograph was taken on the island of Great Inagua along the coast. The flat dark surface in the foreground is the top of a fossil coral reef (“Reef I”) formed during the Last Interglacial (LIG) about 123,000 years ago. It was eroded down to this flat surface when sea-level dropped, exposing the reef to waves and eventually terrestrial weathering. The student sitting on this surface is Emily Ann Griffin (’07), one of three I.S. students who helped with parts of this project. (The others were Allison Cornett (’00) and Ann Steward (’07).) Behind Emily Ann is a coral accumulation of a reef (“Reef II”) that grew on the eroded surface after sea-level rose again about 119,000 years ago. These two reefs show, then, that sea-level dropped for about 4000 years, eroding the first reef, and then rose again to its previous level, allowing the second reef to grow. (You can see an unlabeled version of the photograph here.) The photograph at the top of this post is a small version of the same surface.

The significance of this set of reefs is that the erosion surface separating them can be seen throughout the world as evidence of a rapid global sea-level event during the Last Interglacial. Because the LIG had warm climatic conditions similar to what we will likely experience in the near future, it is crucial to know how something as important as sea-level may respond. The only way sea-level can fluctuate like this is if glacial ice volume changes, meaning there must have been an interval of global cooling (producing greater glacial ice volume) that lowered sea-level about 123,000 years ago, and then global warming (melting the ice) that raised it again within 4000 years. As we write in the paper, “This is of great scientific and societal interest because the LIG has often been cited as an analogue for future sea-level change. Estimates of LIG sea-level change, which took place in a world warmer than that of today, are crucial for estimates of future rates of rise under IPCC warming scenarios.” With our evidence we can show a magnitude and timing of an ancient sea-level fluctuation due to climate change.

Much of the paper concerns the dating techniques and issues (which is why Bill Thompson, the essential geochronologist, is the primary author). It is the dating of the corals that makes the story globally useful and significant. Here, though, I want to tell how the surface was discovered in the first place. It is a paleontological tale.

In the summer of 1991 I worked with Al Curran and Brian White on San Salvador Island in The Bahamas. They were concentrating on watery tasks that involved scuba diving, boats and the like, while I stayed on dry land (my preferred environment by far). I explored a famous fossil coral exposure called the Cockburntown Reef (Upper Pleistocene, Eemian) that Brian and Al had carefully mapped out over the past decade. The Bahamian government had recently authorized a new harbor on that part of the coastline and a large section of the fossil reef was dynamited away. The Cockburntown Reef now had a very fresh exposure in the new excavation quite different from the blackened part of the old reef we were used to. Immediately visible was a horizontal surface running through the reef marked by large clam borings called Gastrochaenolites (see below) and small borings (Entobia) made by clionaid sponges (see the image at the top of this post).
Inside the borings were long narrow bivalve shells belonging to the species Coralliophaga coralliophaga (which means “coral eater”; see below) and remnants of an ancient terrestrial soil (a paleosol). This surface was clearly a wave-cut platform later buried under a tropical soil.


My colleagues and I could trace this surface into the old, undynamited part of the Cockburntown Reef, then to other Eemian reefs on San Salvador, and then to other Bahamian islands like Great Inagua in the far south. Eventually this proved to be a global erosion surface described or at least mentioned in many papers, but its significance as an indicator of rapid eustatic sea-level fall and rise was heretofore unrecognized. Finally getting uranium-thorium radioactive dates on the corals above and below the erosion surface placed this surface in a time framework and ultimately as part of the history of global climate change.

This project began 20 years ago with the discovery of small holes left in an eroded surface by humble sponges and clams. Another example of the practical value of paleontology.

References:

Thompson, W.G., Curran, H.A., Wilson, M.A. and White, B. 2011. Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas coral. Nature Geoscience (DOI: 10.1038/NGEO1253).

White, B.H., Curran, H.A. and Wilson, M.A. 1998. Bahamian coral reefs yield evidence of a brief sea-level lowstand during the last interglacial. Carbonates and Evaporites 13: 10-22.

Wilson, M.A., Curran, H.A. and White, B. 1998. Paleontological evidence of a brief global sea-level event during the last interglacial. Lethaia 31: 241-250.

Non-stationarity in climatic response of coastal tree species along the Gulf of Alaska (Senior Independent Study Thesis by Stephanie Jarvis)

April 15th, 2011

The crew in their XtraTufs. From L-R: Stephanie, Deb, Dan, and Greg.

Editor’s note: Senior Independent Study (I.S.) is a year-long program at The College of Wooster in which each student completes a research project and thesis with a faculty mentor.  We particularly enjoy I.S. in the Geology Department because there are so many cool things to do for both the faculty advisor and the student.  We are now posting abstracts of each study as they become available.  The following was written by Stephanie Jarvis, a senior geology and biology double major from Shelbyville, KY.  Here is a link to Stephanie’s final PowerPoint presentation on this project as a movie file (which can be paused at any point). You can see earlier blog posts from her field work by clicking the Alaska tag to the right.

For my IS field work I traveled to Glacier Bay National Park & Preserve, Alaska with my geology advisor, Greg Wiles.  Our field crew also consisted of Deb Prinkey (’01), Dan Lawson (CRREL), and Justin Smith, captain of the RV Capelin.  My focus was on sampling mountain hemlock (Tsuga mertensiana (Bong.) Carrière) at treeline sites to study climate response and forest health using tree ring analysis.  While in Glacier Bay, we also sampled interstadial wood (from forests run over from the glaciers that were now being exposed on the shore) and did some maintenance work on Dan’s climate stations throughout the park.  Back in the lab, Wooster junior Sarah Appleton kept me company and helped me out with some of the tree-ring processing, as did Nick Wiesenberg.

The view from treeline.

An interstadial wood stump, in place. The glacier ran over this tree and buried it in sediment, which is now being washed away.

Site map

I ended up processing cores from only one of the three sites I sampled this summer (the others can be fodder for future projects!).  In addition, I used data from several other sites sampled in previous years.  My data consisted of 3 mountain hemlock sites forming an elevational transect along Beartrack Mountain in Glacier Bay (one described by Alex Trutko ’08), 3 mountain hemlock sites at varying elevations from the mountains around Juneau, AK, and 2 Alaskan yellow-cedar sites (Chamaecyparis nootkatensis (D. Don) Spach) from Glacier Bay used by Colin Mennett (’10).   My purpose was to look into the assumption of stationarity in growth response to climate of trees over time and changing climatic conditions.  According to the Alaska Climate Research Center, this part of AK as warmed 1.8°C over the past 50 years.

Tree-ring base climate reconstructions are important in our understanding of climatic variations and are a main temperature proxy in IPCC’s 2007 report on climate change.  Climate reconstruction is based on the premise that trees at a site are responding to the same environmental variables today that they always have (thus, they are stationary in their response), allowing for the reconstruction of climatic variables using today’s relationship between annual growth and climate.

Greg coring a tree at treeline.

Crossdating using patterns of variations in ring width.

Temperature reconstructions using different proxies, including tree-rings, from the Intergovernmental Panel on Climate Change’s 2007 report.

Recent observations, such as divergence (the uncoupling of long-term trends in temperature and annual growth) and worldwide warming-induced tree mortality, suggest that this assumption of stationarity may not be valid in some cases.  Using mean monthly temperature and precipitation data from Sitka, AK that begin in the 1830s, I compared correlations of annual growth in mountain hemlock to climate at different elevations over time.  My results indicate that mountain hemlocks at low elevations are experiencing a negative change in response to warm temperatures with time, whereas those at high elevations are experiencing a release in growth with warming.  Low-elevation correlation patterns are similar to those of lower-elevation Alaskan yellow-cedar, which is currently in decline due to early loss of protective snowpack with warming.  An increasing positive trend in correlation to April precipitation and mountain hemlock growth indicates that spring snowpack may be playing an increased role in mountain hemlock growth as temperatures warm.  The high elevation mountain hemlock trends suggest the possibility of tree-line advance, though I was not able to determine if regeneration past the current treeline is occurring.  Tree at mid-elevation sites seem to be the least affected by non-stationarity, remaining relatively constant in their growth response throughout the studied time period.  This indicates that reconstructions using mid-elevation sites are likely to be more accurate, as the climatic variable they are sensitive to is not as likely to have changed over time.

Cedar chronologies (green lines) compared to temperature (brown line). Bar graph represents correlation coefficients between annual ring width and temperature, with colors corresponding to labels on the chronologies (orange is lowest elevation PI, blue is higher elevation ER). Asterisks represent significant correlations. Note that the relationship has changed from being positive at ER during the Little Ice Age to negative by the second half of the 20th century.

Mountain hemlock chronologies (green lines) compared to temperature (brown line). The top graph is of the Glacier Bay sites, the bottom is of the Juneau sites. Red represents the low elevation sites, green the mid-elevation, and purple the high elevation. Note that the low elevation sites are decreasing in correlation as the cedars have, while the high elevation sites have experienced a release in growth with warming.

 

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