Cor nell College
2011-2013
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S p a r k s F r o m T h e R o c k p i le
Newsletter
S PA R K S F RO M T H E R O C K P I L E
HONOR SOCIET Y RETURNS TO
G E O LO GY D E PA R T M E N T
The Beta Pi Chapter of the Earth Science honor society Sigma Gamma Epsilon (SGE)
was reactivated by the Department of Geology during an initiation ceremony in May
2009. SGE was established in 1915 to recognize scholarship and professionalism in
the Earth Sciences. The Beta Pi Chapter was installed initially at Cornell College in
1957, becoming the first chapter of the honor society in the state of Iowa. By 1967, the
chapter had become inactive, largely due to the lack of male students qualified to become members. The barring of women members was listed as a concern of the Cornell
chapter in a series of letters written to the national secretary in 1967 and 1968. Women were allowed membership beginning in late 1967.
To qualify for membership, students must maintain at least a 3.0 GPA in all of their
geology coursework, have taken a minimum of three geology courses, and maintained a
2.67 overall GPA. Our top majors organized an initiation ceremony following guidelines
provided by the national secretary. The ceremony is held at the Pal and is officiated by
the current SGE president. New SGE members are each holding a white carnation, the
official flower of the society. The Geology Department at Cornell is fortunate to have a
cadre of bright, motivated, enthusiastic and smart young scientists currently in the
program.
We’re on the Web!
http://cornellcollege.edu/geology
FROM THE CHAIR
Dear Geology Alumni,
The past two years have seen some significant changes in the geology department, not the least of
which was Ben’s appointment to a three-year term as Associate Dean of the College. Last year (his
first year in the Dean position), Ben taught three classes for the department, but for the next two
years he will only teach one (the Bahamas course). While we are thrilled for Ben and for the college, it left us scrambling to figure out how to replace 1/3rd of our department. Fortunately, we
were able to solve the dilemma. Last year, we were delighted to welcome a recent alumna, Kelsey
Feser, back to teach Invertebrate Paleontology and Historical Geology. Kelsey is working on her
Ph.D. in invertebrate paleontology at the University of Cincinnati. After a successful national search
this year, we are pleased to announce that we will be joined for the next two years by John Orcutt, a
vertebrate paleontologist interested in paleoecology. John will join us as a Post-Doctoral Fellow,
meaning that he will teach 4 blocks each year and will also be available to mentor students in
research.
We are relieved to have hired John, because the number of geology majors keeps growing. Most of
our majors courses for next year are over-enrolled, and as of the end of this academic year, we had
26 declared majors. Our graduating class this year was small (4 geology majors and 1 geology
teaching major), which means that our rising senior and junior classes are exceptional. In fact, the
number of geology majors is greater than the number of most other 3-faculty department majors
on campus. We are hoping that Facilities will be able to make some simple changes in our upperlevel classroom (Norton 108) this summer to allow us to accommodate the greater number of
students. At present, the classroom seats 12 comfortably (15 uncomfortably); we hope the changes will allow for at least 16 students to be comfortable. I am actually teaching two sections of
Igneous Petrology next year, because 25 students signed up for the course (and 22 of them need
to take it next year, since it is required and only offered every-other year).
Not only is the major growing, but the majors are becoming more actively involved in research and
summer geology experiences. Geology students continue to be an impressive force at the annual
Student Symposium, with 10 students presenting last year and 7 presenting this year. Two students completed honors theses last year, and three juniors worked on their honors thesis research
this year (to be completed next year). Last summer two majors were selected for highly competitive
NSF-funded summer research experiences, four majors pursued research with department faculty,
and two others earned government geological positions at the Iowa DNR and with the GeoCorps
Geologist-in-the-Parks program. This summer, three students received NSF-REU positions, four are
working with department faculty, one was awarded a Cornell Fellows research internship, one is
headed to Alaska with GeoCorps, and two others are interning at the Iowa DNR and the Field Museum in Chicago. Needless to say, we are very proud of their achievements.
We enjoy hearing from you all, and we hope you will keep in touch—send an email, drop us a note,
or stop by to visit.
Wishing you the best,
Emily
DEPARTMENT
OF
GEOLOGY
ASSEMBLED AND EDITED BY MICHAEL BARTHELMES
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2011-2013
S p a r k s F r o m T h e R o c k p i le
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CORNELL COLLEGE DEPARTMENT OF GEOLOGY
NORTON GEOLOGY RENOVATIONS
The Geology Department serves students desiring a major
or minor in geology. We offer a basic curriculum of upper-level
courses which, along with supporting coursework in other sciences and mathematics, prepare our graduates for entry-level occupations in government and industry, or for graduate-level education in Geology or Environmental Science at institutions across the
country. Our curriculum also prepares students who choose careers in Earth Science teaching. The department offers several
block-long field courses in diverse areas around the world. We
especially encourage and support independent research projects
by our students. In concert with several departments across several divisions of the college, we lead Cornell's Environmental Studies Program. Many students have taken advantage of environmental-related research and internship opportunities funded
though Geology Department research funds or the Cornell Fellows
program.
Ask any Cornell College geology major what their favorite building
on campus is and the inevitable answer is Norton Geology Center. The
unique features of the building—from the submarine-esque spiral staircase leading to the computer lab and the “bat-cave” rock-saw room, to
the well-worn couch in the student lounge and the Anderson Geology
Museum that encompasses the entire building—make Norton Geology as
much a home to geology students as any dorm room.
However, with growing class sizes and technological demands,
the need to make modern improvements to Norton has been realized in
several key renovations these past two years. Perhaps most importantly
for the aesthetic qualities of the building, the lighting for the museum has
been entirely updated. Stan Crocker, renowned lighting designer who has
worked with Sting, Santana, Stephen Colbert and Ozzy Osbourne, among
many others, was involved in choosing the best lighting options and
placement. This has made a huge difference in highlighting the displays
and brightening the entire building.
Additionally, the main lobbies on the 2nd and 3rd floors have
been opened up by removing some of the outdated hanging pictures and
displays, allowing visitors to better appreciate the architecture of the
building. The moldy brown carpet has been removed and replaced with a
faux-wood flooring and much of the paint has been touched up, giving a
building a much needed breath of fresh air.
Finally, several map and specimen cases from the upstairs classrooms have been removed, allowing more desk space and allowing both
lab and lecture of Physical Geology classes to be taught in the same
classroom. In Room 108 seating is being increased to 16 (from 12), and
the purchase of new polarizing and stereozoom microscopes will allow for
larger major classes to be housed more comfortably.
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2011-2013
NEW PALEONTOLOGY PROFESSOR DR. JOHN ORCUTT
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NOTE FROM BEN GREENSTEIN
Greetings geology alumni,
Greetings,
My name is John Orcutt, and I’m excited to be
joining the Department of Geology at Cornell
as a Post-Doctoral Teacher-Scholar starting
this August. I am a paleoecologist, with a
particular interest in studying how mammals
have interacted with their environment over
the course of the Cenozoic and in using my
results to help predict how living mammals
will respond to future climate change. Many
of the biggest uncertainties regarding the
effects of climate change can be addressed
by looking at what happened the last time
Earth underwent a major period of warming:
the increase in temperature that brought
about the retreat of glaciers around the world
following the Last Glacial Maximum, roughly
19,000 years ago. Working in Iowa, near the
edge of what was once the North American
ice sheet, will give me a chance to pursue the
answers to several questions raised by my
previous research. Did mammal body size
change as the result of warming climate at
the end of the last Ice Age? If not, what does
account for the geographic variation in body
size seen in most modern mammals? Why
don’t ranges of small mammals shift as significantly during glacial advances as ecological
models suggest they should? Is it because
these animals are more adaptable than their
modern ranges might suggest, or is it because
the conditions near the edge of the ice sheets
were less harsh than had been previously
thought? It may seem like I’m tackling some
questions that will be too big to answer over
the course of a two-year job, but I will have the
benefit of not only being located near several
important fossil localities and museum collections, but of working with Cornell students, for
whom there will be several opportunities to
begin projects of their own within my research
program.
S p a r k s F r o m T h e R o c k p i le
Much has happened in the two years since you received the department’s last newsletter. The projects in Curaçao and with the literature database I mentioned in my last report have come to fruition.
I presented the results of the Curaçao work at the national GSA meeting in Minneapolis in October
2011. We learned that coral communities in reef crest and back reef environments did not show
ecological succession even though the water depth in which they were living decreased 2-4 m over
the interval the reefs were alive during Late Pleistocene time.
There was an excellent turn out of former Cornell paleontology students at the meeting – all of whom
are in graduate school and all of whom gave talks at the GSA meeting. I have included a photo of the
“Cornell College Paleontology Research Group” in this issue of Sparks.
I’m not only looking forward to working at
Cornell, but to exploring Iowa as well. I’ve
visited the state several times, but always
briefly, and it will be great to have the chance
to spend much more time getting to know an
area that happens to be particularly rich in
my family history. Midwest winters might
seem like anathema to someone who enjoys
getting outdoors and is accustomed to the
mild rain and fog of the Northwest, but I have
big plans to get back into cross-country skiing, an activity that I enjoyed as a child and
that seems ideally suited to the Iowa landscape and climate. I’m also a big baseball
fan, and was delighted to see that one of the
minor league affiliates of my beloved Seattle
Mariners plays just over an hour’s drive from
Mt. Vernon, which should make for some nice
summer day trips. I can’t wait to get settled
in this August and to start my life in Iowa and
my work at Cornell!
The literature database yielded some interesting results related to the timing of the decline of the
two important species of Acropora in the Caribbean region. I crafted a couple of motion charts using
my data – and you are welcome to play with them at http://cornellcollege.edu/geology/greenstein/
personal/Res.shtml. You can choose either reef crest or mid-slope environments and them pick from
a list of corals (try A. palmata vs. M. complanata in the reef crest, or A. cervicornis vs. M. annularis
from the reef slope) and then watch their relative abundances change over time within different
countries. I presented these results at the 12th International Coral Reef Symposium in Cairns, Australia, in early July last year. The data have been incorporated into a 300 page report entitled Status
and Trends of Caribbean Coral Reefs: 1969-2012, published by the Global Coral Reef Monitoring
Network and a few other NGOs. An additional (much shorter) report is scheduled to be published in
Science later this year.
I joined colleague Karl-Heinz Wyrwoll from the University of Western Australia for two weeks of field
work in coastal W. Australia in June last year. We are working on the timing and extent of a double
peak in sea level during Late Pleistocene time. Coastal Australia is a great place to do fieldwork if
one can avoid be eaten by large fish, bitten by large snakes, or stung by a variety of arthropods. Two
trips to Australia (for the fieldwork and then the meeting in Cairns) within a five-week interval left me
jet-lagged for a month.
It was thus not surprising that attending the Noel-Levitz National Conference on Student Recruitment, Marketing and Retention in Chicago shortly after the trip to Cairns was a surreal experience –
the otherworldly nature of the meeting amplified by the fact I was attending it in my new role as
Associate Dean of the College. The three-year appointment, which began on July 1 last year, allows
me to learn a great deal as I lead first year programming, faculty development and off-campus studies at the college. I head to Harvard on 1st June to participate in a Management Development
Program offered through their Institute of Higher Education. I am looking forward to learning more
about leadership in an academic setting, and also being able to say that I was a student at Harvard.
Tomorrow Janet and I leave for NYC, where we will celebrate Jonah’s graduation from NYU at an
intimate commencement ceremony held in Yankee Stadium. Radio City Music Hall is the venue for
festivities related to his graduation from the Tisch School of the Arts – I am expecting a hot dog at
one event and the Rockettes at the other. Janet and I are housing (and feeding) a dozen or so film
crewmembers that are traveling to Mt. Vernon from NYC to shoot Jonah’s senior thesis film during
the last two weeks of June. Elijah just completed his first year in a Ph.D. program in East Asian History at Princeton after spending the last two years in Japan. Janet and I continue to marvel at our sons’
experiences and bemoan our advancing age.
Best to all of you and don’t hesitate to stop by if you’re in town (you’ll find me in Old Sem).
2011-2013
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NOTE FROM EMILY WALSH
Greetings to all!
The past two years have been productive years for me at Cornell. I received tenure at
the end of academic year 2010-11 and took my sabbatical during the fall semester of
2011-12. Wow, sabbatical was fantastic. I did not travel but rather stayed right in
town and worked on writing up some of my ongoing research projects. While I enjoy
teaching on the block plan, it can be hard to find time during busy blocks to keep the
research going steadily. The result for me is a backlog of research projects that need
to be finalized and turned into manuscripts. Currently, I am working on revisions for
one of the manuscripts regarding the cooling and uplift that took place during the final
stages of the Norwegian Caledonide orogeny. Last year two of my research students
wrote honors theses on the pressure-temperature histories of eclogites from the ultrahigh-pressure North Qaidam mountains in western China. That project is ongoing. This
past summer I began a new project with a colleague from Oberlin college on Santa
Catalina Island, CA. We received a grant from the Keck Geological Consortium and
took 6 undergraduate students from across the country with us to examine the Cretaceous subduction zone exposed on the island. This project, too, is ongoing.
This year I took over as department chair and joined the Review, Tenure & Promotion
Committee of the college—two service positions that required quite a lot of time. I
continue in both positions next year, but I can see that having one year of experience
under my belt will help me become more efficient in both. In addition, I taught a brand
new course, Metamorphic Petrology (which used to be combined with Igneous Petrology), and a new version of my upper-level elective, Origin of Mountains. Students
worked hard in Metamorphic Petrology, making their own thin sections and analyzing
a “pet rock” from the department’s extensive rock collections. The results were quite
impressive. I was also immensely impressed with the students in Origins who wrote
mini-NSF proposals for research projects of their own creation in a mountain belt they
had just learned about that block (the Urals).
Jonathan and I are having a wonderful time watching Franklin grow and change—he
will turn 3 this summer and every day is a new adventure. Both of them joined me on
Santa Catalina Island last summer, camping with the bison and playing at the beaches. Hard to beat that!
NOTE FROM RHAWN DENNISTON
Dear Cornell Alumni,
Greetings! Life in the department is as busy as always. As for my research, a longsimmering project that I began in 2004 in Portugal is now taking off, and I have a couple
of students joining me in fieldwork, as well as time in the labs at Iowa State and the
University of New Mexico. By analyzing stalagmites, we are finding that during the last
glacial period (the last 100,000 years or so), rainfall in Portugal was ramped up and then
clamped down by temperature shifts in the North Atlantic that are recorded in the Greenland ice cap. The research in northern Australia is funded by an NSF grant which I received a year-and-a-half ago. There, my students and I have reconstructed the behavior
of the Australian summer monsoon over the past 40,000 years and have found that it
varied in concert with Greenland, just like Portugal does, although when Portugal got
wetter, Australia got drier. Despite this work, there is still a lot to do. I am heading back
to Portugal this summer for more fieldwork, and I hope to get back to Australia next summer. I have a suite of excellent and extremely hard working research students who keep
me on the ball and excited.
Jen and the girls are doing well. Anna is now in 7th grade and really seems to like it
despite her occasional claims to the contrary. She has become a huge fan of Sherlock
Holmes – both the Arthur Conan Doyle stories and the BBC series “Sherlock”. Harper is
a rapidly sprouting 4th grader who, as I write, is covered from head to toe in mud as she
and a friend do something slightly geological/archeological/agricultural in our back yard.
Harper and two friends have formed a band “Night Owls” (consisting of electric piano,
vocals, and drums – Harper is the drummer) and so far have two original songs to their
credit, one of which reminisces about those early days (prior to 4th grade, I guess) when
life was so carefree. Hmmm.
I love hearing from your news, so please send me an email if you have the time
(RDenniston@CornellCollege.edu).
Let us hear from you!
Best wishes to all,
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Best,
Emily
Rhawn
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2011-2013
Geology Field Trips 2011-2013
GEOMORPHOLOGY IN
SOUTH DAKOTA 2011
GEOLOGY OF A REGION:
NEW ZEALAND 2012
“The whole world is, to
me, very much ‘alive’ - all
the little growing things,
even the rocks...The same
goes for a mountain, or a
bit of the ocean, or a
magnificent piece of old
wood.” -Ansel Adams
BAHAMAS 2012 & 2013
S p a r k s F r o m T h e R o c k p i le
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NEW ZEALAND 2012
In February of 2012, a class of 12 students, Prof. Rhawn Denniston
and three of his friends, including economics professor Todd Knoop and
Biology professor Lenny Gannes, left the Iowa winter and embarked on the
long trip to reach the South Island of New Zealand. Once we finally reached
Nelson, we began the long drive to the field station near Takaka where we
spent a week and a half exploring a detailed mapping project of Farwell Spit.
We grew to love the field station and the beautiful coast around Takaka; as
well as The Mussle, the great tavern down the road.
We then spent a few days in Hokitika and completed a mapping
project of the Alpine fault. After this we moved even farther southward, working our way toward Franz Josef. Along the way we stopped and hiked down
into a gulley full of beautiful garnet schist and actually put our hand on the
contact of the Alpine Fault! It was a fantastic experience to actually touch a
geologic feature that stretches across the entire country. We then moved on
to Franz Josef where we hiked on the Franz Josef Glacier in pouring rain; one
of the highlights of the trip despite how cold we were. The trip concluded
with the long scenic drive back to Nelson where we spent the last couple of
days enjoying the beautiful city and going on a 9-hour hike to the top of Dun
Mountain, the name locality of dunite. Although we were sad to let New Zealand go, we left with a better understanding of geology and returned to campus feeling invigorated. The class grew extremely close on that trip and will
forever hold those memories and the knowledge gained.
Daniel Pawlak ‘13
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2011-2013
BAHAMAS 2013
Cornell College is known for offering “one extraordinary opportunity at a time”
with their unique academic block program. The Modern and Ancient Carbonate Systems of the Bahamas class is a prime example of why students at
Cornell benefit so much from the block program. Only at Cornell are students
given the opportunity to travel to a tropical island for an entire month, during
the middle of the academic school year. As a geology major I was required to
take a field course, but what better way to meet this requirement then to
study corals in San Salvador, Bahamas, while escaping the harsh Iowa winter? For a month, we were given the opportunity to snorkel numerous coral
reefs, climb through flank margin caves, and of course bask on the various
beaches. However, it wasn’t all fun in the sun. Cornell College is also known
for its academic rigor, and this course was no exception. While enjoying ourselves on a topical island, we were also educated on the dynamic systems
that create the island’s stratigraphy, how to recognize specific fossils in the
rock record, and other important skills that every geologist will need after
graduation. It was a true test of knowledge and endurance, but it was also
one of the most fulfilling and exciting classes I’ve taken during my college
career.
Stephanie Wheeler ‘14
S p a r k s F r o m T h e R o c k p i le
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STUDENT RESARCH: KECK CATALINA 2012-13
Being accepted and funded for a year-long Keck Geology Consortium project
studying metamorphic rocks on Santa Catalina Island, California, was an extraordinary opportunity. Myself, Dr. Walsh and five other undergraduates from
colleges across the nation, as well as Dr. Zeb Page of Oberlin College spent
three weeks exploring and collecting samples (and playing with bison, island
foxes and hacky-sacks) on Santa Catalina Island. Because each undergrad was
working on an individualized project, our experience of the island’s geology
was extremely in-depth and varied. Additionally, the connections I formed with
the other students are long-lasting friendships that I value to this day.
After a summer of field work on the
island, and a week of preliminary lab
work at Oberlin College, OH, each
student worked on their project
throughout the year. Some of the
projects became honors theses,
others senior theses; but after a year
of research we returned to California,
to Pomona College, to present at the annual Keck Geology Symposium. Seeing
everyone’s hard work pay off, and learning what other Keck students had been
working on was a highlight of the year for me. It was also very exciting to be on
a flight where everyone is holding a poster tube, and the word “subduction”
can actually be overheard in casual conversation…
Michael Barthelmes ‘13
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2011-2013
STUDENT RESEARCH: NEW MEXICO 2012
During the summer of 2012, I went to the University of New Mexico with Professor
Rhawn Denniston and assisted his research for two months with two other students.
While there, we polished slabs of stalagmites using a handheld sander and milled
them with a computer-guided drill bit. We processed the more than 100 samples in
the clean lab with wet chemistry procedures to measure the amount of thorium and
uranium within each sample. Finally, we assisted Professor Denniston in running a
Neptune mass spectrometer to obtain uranium and thorium isotopic ratios to get accurate dates for each sample. In addition to the lab-work during the weekdays, we hiked
in the nearby mountains to learn about the local geology on the weekends.
This experience allowed me to obtain essential skills such as polishing, drilling, and
uranium/thorium dating, which are all very useful skills in the art of paleoclimate reconstruction. The experience taught me physical and mental endurance, and helped
prepare me for a life of field-work.
Ni An ‘14
Conducting research at the University of New
Mexico provided me with an amazing experience. While I was there, I learned how to date
stalagmites using U-Th dating techniques and
how to work with others in a lab setting. Basically, the process of dating stalagmites involves drilling samples from interesting areas
of the stalagmite, processing them through
various chemical procedures, and then running them on a mass spectrometer. Though
the days could be long, and I spent a lot of
time in the lab waiting for samples to go
through various chemical processes, I gained
lab skills and confidence. However, I was not
stuck in the lab the entire time in New Mexico. During days off my peers and I visited a
few places of geological interest, such as Tent
Rocks National Monument, Ghost Ranch, and
the Valles Caldera National Preserve. Overall,
this research experience has allowed me to
work on a thesis and has provided me with
the skills needed to conduct research this
summer at the University of Texas.
Angelique Gonzales ‘14
S p a r k s F r o m T h e R o c k p i le
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STUDENT RESEARCH: PORTUGAL 2012
In the summer of 2012 I had the privilege of accompanying my advisor,
Rhawn Denniston, to Portugal to help collect stalagmites from two caves.
We joined a colleague of his, Jonathan Haws, an anthropology professor at
the University of Louisville. The first cave we sampled involved a twenty-foot
descent down a steel cable ladder. It was not a very deep cave, ~150m
long, but it was well decorated. We were able to collect several samples
from this cave, all of which had already been broken off. The next cave,
fondly known as Buraca Gloriosa or “Glory Hole”, required a tight squeeze
through a hole, feet first, and then a climb down a root to get into the body
of the cave. This cave was bigger and deeper than the previous cave, but
not as well decorated. We collected two stalagmites, one of which was a
three-foot long piece, weighing 90 lbs, that continues a sample Rhawn had
collected in 2006. It is this sample that I decided to work on for my honors
thesis.
After shipping all the samples back to the USA, I met Rhawn at the
University of New Mexico in Albuquerque during late summer, and we performed U-Th series dating on the samples using the Inductively-Coupled
Plasma Mass Spectrometer. Then in the fall, I took my sample to Iowa State
where, under the direction of Al Wannamaker, I drilled for and analyzed
carbon and oxygen isotopes. This allowed me to begin reconstructing climate in Portugal for the last glacial cycle, the topic of my honors thesis.
Amanda Houts ‘14
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2011-2013
CORNELL COLLEGE GEOLOGY
S p a r k s F r o m T h e R o c k p i le
Using eclogites to decode the pressure–temperature history of an ultrahighpressure metamorphic zone, North Qaidam, China
Honors Thesis, Robin Drucker
2012 Graduating Majors: Luke Anderson, Matt Ash, Robin Drucker, Chelsea Nissen,
Elizabeth Greaves, Wilson Keys, James Ostrander, Julian Peota, Andrew Roers,
Bill Rood, Ellen Shank, Nic Slater
2013 Graduating Majors: Mike Barthelmes, Dan Pawlak, Daniel Cleary, David Allen, Shannon Carty (Geology Teaching major)
Student Awards and Honors
Herbert Hendriks Award (to the top senior geology major)
2012. Chelsea Nissen
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The North Qaidam Mountains on the northeastern edge of the Tibetan plateau contain
an ultrahigh-pressure (U)HP metamorphic terrane. The region has been deformed,
uplifted and tilted by the Himalayan orogeny, exposing a ~10 km thickness of
metamorphosed crust at the surface (Menold et al., 2009). This tilting combined with the
desert conditions of the region provides excellent exposure and access to (U)HP rocks,
making it the site of many studies on the mechanics of (U)HP metamorphism and
William H. Norton Geology Prize (to the top junior geology major)
exhumation. The area is still not well understood, with large variations in metamorphic
2012. Michael Barthelmes
dates and peak pressure–temperature estimates throughout the region. We analyzed
2013. Ni An, Angelique Gonzales
eclogites from the NW part of the North Qaidam Mountains, the Luliangshan, for
pressure-temperature estimates. We found peak pressures of 24.5 ± 4 kbar at 508 ±
Gene Hinman Geology Prize (for excellence in field research)
90°C from sample CM-5-27-04-7A and 23.9 ± 5 kbar at 650 ± 100°C from sample
2012. Angelique Gonzales
CM-6-6-04-8A. Our samples indicate late stage heating as well as possible UHP
2013. Amanda Houts
conditions in the region.
Paul Garvin Geology Prize (to the top sophomore geology major)
2012. Ni An, Amanda Houts
2013. Setsen Altan-Ochir
Student Symposium
A full list of Symposium contributions and abstracts can be found on the college website at this address:
http://symposium.cornellcollege.edu/category/geology/
Following is a selection of abstracts of the varied topics that have been featured at
recent symposiums.
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2011-2013
Major and minor elemental analysis of eclogitic garnets from the North
Qaidam (U)HP metamorphic belt; implications for thermobarometry
Honors Thesis, Chelsea Nissen
The North Qaidam (ultra)high-pressure metamorphic belt (NQMB) is located on
the northeastern corner of the Tibetan Plateau. It is composed of multiple suture zones
and terranes that have been tectonically altered. The NQMB is roughly 15 km wide,
extends 350 km NW-SE, and contains well-exposed continental collision-type
(ultra)high-pressure [(U)HP)] metamorphic rocks. Eclogites in the NQMB occur as
blocks, boudins or layers within the host orthogneiss. The eclogites hold pressure
indicator minerals in fluid-reduced conditions, resulting in slow reaction rates. This
makes them ideal rocks for pressure–temperature (PT) studies. Thermobarometry
calculations from eclogites and (U)HP gneisses has been used to decipher PT histories
along the NQMB; however, many of the eclogites in the area do not contain an ideal
mineral assemblage for conventional thermobarometry. Likewise, eclogite sample
E9814B1, from the northwestern end of the NQMB, contains only
garnet+clinopyroxene+biotite+quartz. However, the size of the garnets (3-5 mm
diameter), the lack of inclusions in garnet, and the overall lack of retrograde
metamorphism, makes sample E9814B1 ideal for detailed element diffusion studies.
We analyzed major and trace elements in the garnets of sample E9814B1 by
electron microprobe (EMP) and laser-ablation inductively coupled plasma mass
spectrometry( LA-ICP-MS). Major and trace element patterns reveal three stages of
prograde garnet growth, which produced a well-defined core, outer core (mantle) and
rim within each garnet. Major elements (Ca, Mg, Mn, Fe), light rare earth elements and
middle rare earth elements show bell-shaped distribution profiles, across each grain,
indicating element distribution through Rayleigh fractionation, whereas vanadium and
scandium exhibit M-shaped profiles, likely designating diffusion-limited distribution
(Skora et al., 2006). Major element zoning and diffusion rates allow for estimation of PT
conditions of prograde growth of the sample, indicating three distinct stages of
S p a r k s F r o m T h e R o c k p i le
Page 18
Sea Level Rise and Fall Recorded in The Bahamas Caused by
Glacial Events and the Future Impacts of Sea Level on World
Population
Daniel Pawlak
The last several hundred
thousand years have witnessed dramatic changes
in sea level due to the
growth and decay of the
Greenland, Antarctic, and
now-melted North American continental ice sheets.
The last time sea level
exceeded modern day
levels was 120,000 years
ago, at which time it was as
much as 6-8 m above present. Given that 10% of the
world’s population lives in
low lying coastal regions,
understanding the causes,
mechanisms, and rates of
past sea level changes are
of critical importance.
Several methods have
been developed for reconstructing past sea levels,
including analysis of the
oxygen isotopes of foraminifera. Radiometric dating
of select species of coral
and of submerged flowstones, stalagmites, and
stalactites allows us to
correlate a date with the
already-determined timing
of subaerial exposures.
One limitation to sea level
studies involves tectonic
activity, which raises the
land surface, thus altering
the evidence of past sea
levels. If the tectonic
activity is not corrected
for, then an incorrect sea
level height will be obtained. Therefore, one
area often studied is The
Bahamas Bank, an area
that is tectonically stable
and that can thus record
sea level without the
complications of tectonic
uplift.
This project involves a
synthesis and summary of
sea level reconstructions
from The Bahamas over
the last 120,000 years,
with the goal of understanding the large scale
impact on the world population of sea level rise
above its current day
position due to global
climate change and the
resulting melting of the
continental ice sheets in
Greenland and Antarctica.
“A road cut is
to a geologist as
a $20 bill is to a
starving man”
growth.
John McPhee
Page 19
2011-2013
Tropical Sea Surface Temperatures Over the Last
120,000 Years
David Allen
Sea surface temperature
(SST) is one of the most
important and fundamental
components of Earth’s
climate. Tropical SST determines the location of the
Intertropical Convergence
Zone where the northeast
and southeast trade winds
meet, and influences global
moisture content, the
strength of monsoons, and
precipitation in the tropics.
Therefore, the importance
of understanding the
changes in SST can help us
grasp a better understanding of the effects of climate
change. Several SST proxies have been developed,
including oxygen isotope,
magnesium-calcium, and
strontium-calcium ratios in
foraminifera and corals,
and alkenones in marine
algae and foraminifera, all
of which serve as important
tools in palaeoceanography.
However, each method
offers advantages and
disadvantages. For example, an advantage for the
magnesium-calcium method is that it can be measured along with oxygen
isotope records found in
the same shell of foraminifera.
A drawback to the magnesium-calcium method is that
partial dissolution of foraminifera shells can occur
after the shells reach the
sea floor. This dissolution
can reduce the magnesium-calcium ratio, raising
the apparent temperature.
Our understanding of SST
variability decreases as
we stretch deeper back in
time; but over the last
glacial cycle, fluctuations
in SST occurred coincident with changes in
glacial ice volume, atmospheric temperature, and
changes in ocean circulation. Reconstructed temperature estimates of up
to 5°C warmer than present have been calculated for sea surface temperatures during this time
period. The last time
tropical SST was as high
or higher than today was
during Marine Isotope
Stage 5e (120,000 years
ago), which would imply
similar climate conditions.
This study summarizes
data that show how the
various proxies indicate
fluctuations of SST over
the last glacial cycle and
how applying these results can give us a better
understanding of the
effects of climate change.
S p a r k s F r o m T h e R o c k p i le
Page 20
Characterizing Pyroxene Cooling Rate Using Reflectance
Spectra
Ellen Shank
Pyroxenes are among the
most common minerals in
the inner solar system. The
degree of order/ disorder in
their crystal structure relates to the cooling history
of the mineral. In pyroxenes, Fe2+ prefers the M2
cation site, and Mg prefers
the M1 cation site in the
crystallographic structure;
the slower the pyroxene
cools, the more ordered it
will be. Previous work revealed that the ordering of
Fe2+ and Mg between the
M1 and M2 sites affects
the relative strengths of
absorption bands in the
near-infrared. We performed a series of heating
experiments to help constrain the relationship
between cation ordering
and reflectance spectra
for orthopyroxenes.
For the experiments, 100
mg of crushed orthopyroxene was heated in an
alumina capsule sealed
inside an evacuated highpurity silica tube. A small
piece of iron foil was
placed beneath the capsule to buffer oxygen
fugacity; a small piece of
the iron foil outside the
seal showed the difference between the atmospheres inside and outside
of the tube. The samples
were heated to four different temperatures (500°C,
600°C, 700°C and 800°
C) and were held at those
temperatures for one day
to a month to ensure Mg-
Fe2+ equilibration. Samples were then measured
using near-infrared reflectance spectroscopy and
Mossbauer spectroscopy
to determine the cation
ordering. The results show
that pyroxenes on Earth
are more ordered, having
experienced slower cooling or metamorphism,
while extraterrestrial
materials are more disordered, due to rapid cooling. However, our research will need some
tweaking before doing
final analyses.
Page 21
2011-2013
U/Th Dating of Cold Water Tufa Deposits from Kimberly Region of
Australia
Aaron Campbell
Paleoclimate records from
Indonesia and the West
Pacific Warm Pool (WPWP)
reveal that changes in
global and regional climate
have altered the intensity
and location of IndonesianAustralian Summer Monsoon (IASM) precipitation
over glacial/interglacial
cycles (Magee & Miller,
2004; Griffiths et al., 2009;
Mohtadi et al., 2011).
Understanding the magnitude and timing of monsoon variability in tropical
Western Australia is less
well constrained because
paleoclimate proxies
across the region are
sparse and have been
limited to alluvial sequences (Muller et al., 2008;
Wyrwoll & Miller, 2001)
and shallow marine sediments (Magee & Miller,
2004). Recent stalagmite
records developed in the
Kimberly region of Western Australia provide high
resolution records of
IASM variability over the
past 40,000 years (R.
Denniston, personal communication), but do not
necessarily reflect all
aspects of a changing
hydrologic cycle.
In order to develop a
more complete picture of
changing precipitation
conditions over this time
interval, samples of
groundwater carbonate
(tufa) deposits formed in
the Kimberly region were
dated using U/Th mass
spectrometry tech-
niques. These deposits
track changes in climate
by marking the timing of
groundwater discharge,
which is controlled primarily by the amount of
precipitation that is allowed to infiltrate into
groundwater reservoirs
(Yan et al., 2012).
Samples taken from the
top half meter of the tufa
mound date back approximately 3,000 years, with
a maximum age of 4,800
years. This suggests that
the entire mound could
date back between
35,000 and 57,600
years, providing evidence
for a continued, larger
study.
S p a r k s F r o m T h e R o c k p i le
Page 22
Evolution of a Cretaceous Subduction Model: Insights from the
Catalina Schist
Michael Barthelmes
The Catalina Schist crops
out on Santa Catalina Island and underlies the
southwestern California
borderland, preserving a
Cretaceous subduction
zone environment. The
Catalina Schist consists of
amphibolite-facies rocks
atop a suite of rocks metamorphosed at progressively
lower temperatures with
increasing depth.
This inverted metamorphic
sequence has been explained to be the result of
tectonic juxtaposition of the
subduction zone sequence
with rocks formed in a slabparallel thrust in the forearc. Subsequent subduction erosion and faulting
has juxtaposed the lower
grade blueschist-facies
rocks with the higher grade
units of the Catalina Schist.
The epidote-blueschist
unit of the Catalina Schist
exists between the highgrade epidote-amphibolite
unit and the low-grade
lawsonite-blueschist unit
and was originally
mapped together with the
epidote-amphibolite unit
as the Catalina
greenschist unit. Significant differences in metamorphic grade separate
these units and bring into
question whether the
epidote-blueschist facies
metamorphism occurred
within a slab-parallel
megathrust in the forearc
region or within the accretionary complex of the
subduction zone proper.
Last summer I collected a
series of samples along
Cottonwood Canyon,
starting from apparent
epidote-blueschist at the
bottom to amphibolite at
the top. Thin-section analysis of these samples has
shown a complete lack of
gradation between units,
strongly implying unique
histories of formation and
perhaps the existence of
a second metamorphic
thrust zone. Pseudosection analysis of XRF data
for some samples, as well
as electron microprobe
data, can refine the tectonic model of the Catalina Schist to include specifics regarding the formation of the epidoteblueschist.
“(In geology) we find no
vestige of a beginning –
no prospect of an end..”
James Hutton
Page 23
2011-2013
High-fluid Component in Some Recent Lavas from the Southern
Cascades
Nic Slater
We present U-Th and Sr isotopic data on young (Holocene) lavas from Lassen and Mt
Shasta volcanic fields and surrounding areas. Andesitic lavas from Shasta
have 232Th/238U ratios of 2.6–2.7 and, similar to those reported previously, have
activity ratios (230Th/238U) of 1.01–1.03 close to secular equilibrium. A Holocene
rhyodacite flow from Lassen has a 232Th/238U ratio of 2.9 and (230Th/238U) near
secular equilibrium (0.99), similar to lavas from Shasta reported here and elsewhere.
In contrast, basaltic andesite lavas from the Cinder Cone at Lassen show large U enrichments, 232Th/238U ratios between 1.4 and 1.7 and (230Th/238U) of 0.61–
0.74. These are the highest 238U over 230Th enrichments seen in Cascade lavas,
similar to many arc lavas. Lavas from Lassen, despite large differences in bulk composition of U/Th and (230Th/238U), have similar 87Sr/86Sr ratios (0.703954 –
0.704137). These Sr isotopic ratios are similar to values from other southern Cascade lavas. In contrast, the Shasta lavas have low 87Sr/86Sr ratios (0.702905 0.703118), within the range of local MORB. The similarity in Sr isotopic composition
between the more evolved lavas of Lassen and the Cinder Cone lavas argue against
source variation to explain the U enrichment in the latter. The differences in
(230Th/238U) are reflected in the 232Th/238U ratio, suggesting inherent U over Th
enrichment of the Cinder Cone lavas, most likely due to fluid addition in the mantle.
“Show me a person who throws money into a shifting crack in the ground,
and I’ll show you someone who is generous to a fault.” -Unknown
Address Change Requested
Cornell College
600 1st Street Southwest
Mount Vernon, IA 52314
Our current understanding of trends in tropical cyclone activity in the IndoPacific is restricted by a limited historical record. Mud layers deposited in
stalagmites during flooding events in cave KNI-51 from tropical Western
Australia appear to be a proxy for tropical cyclone activity in the region.
Aragonite stalagmites were precisely dated using U/Th mass spectrometry
techniques, and these high resolution dates were used to construct age
models that can, in turn, be used to calculate the age of each mud layer.
Stalagmite KNI-51-G is 63 cm tall and cylindrically shaped, and preserves
evidence of increased flooding frequency from 1310-1460 AD and decreasing flooding frequency from 1460-1640 AD. These data compare well with
similar analyses of two other stalagmites collected from KNI-51. West Pacific Warm Pool sea surface temperatures, which exert a first-order control on
tropical cyclone activity, track flood layer frequency from 1000-1637 AD
suggesting that tropical cyclone-induced flooding increased during periods
of warmer sea surface temperatures from 1100-1250 AD.
S P A R K S F R OM T H E R O C K P I L E
Mud Layers in Stalagmites: A Proxy for Past Cyclone Activity
Daniel Cleary