C o r n e l l C o l le g e
2007-2009
Newsletter
S PA R K S F RO M T H E R O C K P I L E
HONOR SOCIET Y RETURNS
G E O L O GY D E PA R T M E N T
TO
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 was held at the Pal, and
was officiated by SGE member Ben Greenstein. New SGE
members are each holding a
white carnation, the official
flower of the society. Pictured below are (from L-R): Rebecca Ellerbroek ’09, Kelsey
Feser ‘10, Nick Tripp ‘10, Elizabeth Erickson ‘11, Dana Friend ‘09, Abigail Michaelson
‘09 and Chelsea Korpanty ‘11. Natashia Pierce ‘11, not pictured here, also joined the
Beta Pi Chapter. 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
DEPARTMENT
OF
GEOLOGY
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S p a rk s F r o m T h e R oc k p i l e
FROM THE CHAIR
The last two years have witnessed several cosmetic and technological changes to
Norton Hall as well as important additions to our teaching and research facilities. The
Norton Rock Garden mentioned in the last issue has literally bloomed (the flowers,
that is – the rocks do not seem to have changed much) since I mentioned it in the last
Geology newsletter. Courtesy of Wendling Quarries Inc. and Montgomery Construction,
a series of very large fossiliferous limestones and spectacular crystalline rocks sit atop
15 tons of river gravel. The slabs are interspersed with native grasses, peonies, sedum
and day lilies. The gardens grace both sides of the south entrance to Norton, emphasizing our building as a geology center. A picture of the garden is located inside this
issue of Sparks.
We have updated the thin section lab, acquiring over $30,000 worth of state of the art
grinding and preparatory equipment. The system rendered the grinding laps and
Hillquist machine (the green thing in room 109) obsolete, and we donated the Hillquist
to the Cedar Valley Rocks and Mineral Society’s annual auction. Professor Emily Walsh
has steadily rebuilt and augmented the existing petrology thin section collection, whilst
I have managed to prepare numerous thin sections from materials collected in Western Australia. We have replaced six of the twelve student petrographic microscopes,
and expect to replace the final six microscopes later this year – we have to, as Mineralogy saw an unprecedented initial enrollment of 20 students for next year.
The two introductory laboratories on the third floor were repainted in 2008 and outfitted as technology classrooms. We took this opportunity to remove the old plaster
maps, replace the yellowed curtains with fresh window blinds and remove the large
furniture in the front of each room. A new exhibit was added to the museum in the
form of 13 framed and mounted posters, each with an explanatory caption, distributed
in both third floor labs. The posters, which measure 2’ x 3’, display photographs of
many different thin sections taken through Professor Walsh’s research petrographic
microscope. The Department hosted a “faculty social” this past spring to showcase the
new exhibit, and Herb Hendriks joined us for the occasion.
The Department has an exceptionally talented group of enthusiastic majors forming
the core of the Geology Club. With the help of a generous donation from Bill and Joanna Cook, club members traveled to Moab Utah over spring break to explore the
canyonlands region. Geo Club members also organized the reactivation of Cornell’s
long-dormant Beta Pi Chapter of Sigma Gamma Epsilon, the Earth Science honor society. We also are very pleased to have signed up an unprecedented number of freshman and sophomore students in this last year (see above comment on enrollment in
Mineralogy).
Once again I thank many different donors to our program, including the Cedar Valley
Rock and Minerals Society (now re-named the Cedar Valley Rock Club). Your donations
have never been more important to our students as the college enters challenging
economic times,
As you will see in the pages that follow, the Geology Department continues to be vibrant, global and especially relevant to the mission of Cornell College. Enjoy.
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2007-2009
CORNELL COLLEGE DEPARTMENT OF GEOLOGY—
INFORMATION SHEET
Name ____________________________________________ Cornell Class ________
Graduate Degree(s):
University __________________________________________ Year______________
University __________________________________________ Year______________
Home Address
_____________________________________________________________________
_____________________________________________________________________
Business Address
_____________________________________________________________________
_____________________________________________________________________
Email ________________________________________________________________
Professional and other Activities
_____________________________________________________________________
_____________________________________________________________________
Note: If you know the whereabouts of any of the graduates whose addresses are marked
“unknown” or if you are aware of any changes of address, would you please pass this information along to us? Thanks.
Please return to (or e-mail):
Jackie Stewart
Development Office
Cornell College
600 1st Street West
Mount Vernon, IA 52314
jstewart@cornellcollege.edu
S p a rk s F r o m T h e R oc k p i l e
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CORNELL COLLEGE
DEPARTMENT OF GEOLOGY
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.
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2007-2009
FIELD TRIPS 2007-2009
GEOARCHEOLOGY OF GREECE
GEOMORPHOLOGY IN
SOUTH DAKOTA 2009
GEOLOGY OF NATIONAL PARKS
HAWAII 2008 — SOUTH DAKOTA 2009
SPRING BREAK TRIPS
BIG BEND, TX 2008 — MOAB, UTAH 2009
S p a rk s F r o m T h e R oc k p i l e
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NOTE FROM BEN GREENSTEIN
Hello Geology alumni. As usual the time has flown by since the last issue of Sparks hit
the newsstands. I have made three trips to Australia since the last newsletter. One of
these trips was to work with long-time colleague John Pandolfi at the Australian Research Council Centre of Excellence in Coral Reef Studies at the Centre for Marine Science at the University of Queensland. John and I finished up a paper on our work in
Western Australia, which has been published in the journal Global Change Biology.
The other two trips were to Western Australia to continue work on several Late Pleistocene (Last Interglacial) fossil reefs exposed in that region. One trip was with my colleague Karl-Heinz Wyrwoll, from the University of Western Australia. We travelled to
southern Exmouth Gulf where (fortunately) Karl-Heinz accepted my interpretation of a
“double-peak” in sea level preserved in the rocks. A second trip in May 2008 with Cornell student Kristyn Rodzinyak allowed for detailed measuring and descriptions of the
sections in southern Exmouth Gulf and in Cape Cuvier, farther south along the WA
coast.
I am currently continuing to work on the project in WA (though with no trip planned for
this year) as well as a very large literature-derived research project that investigates the
relative abundances of reef-building corals in the Caribbean region during four distinct
intervals of time: Late Pleistocene, Holocene (fossil), modern reefs pre-1983 and modern reefs post-1983. I have assembled every paper written that describes the corals
present on these reefs during each time interval. Geology major Chelsea Korpanty is
currently helping me to compile data retrieved from the publications. I hope to explore
further whether current coral declines really are unprecedented since Late Pleistocene
time.
I return to San Salvador Island, Bahamas later this month to work with geology major
Kelsey Feser, who will conduct research related to her honors thesis. Kelsey’s work
seeks to ascertain whether the development of Club Med in 1992 has impacted marine
benthic molluscan communities in the bay adjacent to the compound. Kelsey’s work
has larger application – specifically whether molluscan death assemblages can be used
to ascertain community structure that existed prior to human impacts. It has been some
time since I have conducted (or supervised) research on San Salvador, and I am looking
forward to our trip.
Craig Tepper (Cornell Biology) and I continue to collaborate on research that investigates the affinities of two species of fire coral in the Bahamas. Craig is giving a talk on
our work at a symposium on the Natural History of the Bahamas on San Salvador in a
couple of weeks. Normally I would be there but I have to leave San Salvador for the
weekend to give a talk on the geology of the Bahamas to a group of orthopedic surgeons who are having their annual meeting at the Atlantis Resort on Paradise Island in
Nassau (as you might imagine, there is a story attached to this).
Believe it or not, our elder son, Elijah, will be a senior at Penn next year. He has spent
the last 12 months in China participating on three separate academic programs. We
visited Elijah in April and benefited from the fact that he now is fluent in Mandarin Chinese. Elijah is a history major with a concentration in diplomatic history with an emphasis on East Asia. Our younger son, Jonah, leaves for NYU this fall. Jonah was accepted
into the Tisch School of the Arts, Kanbar Film Institute, to study film production. We are
very excited for him, though Janet and I now face the prospect of being empty nesters;
languishing on the prairie whilst our boys live and work on our beloved east coast. Let
us hear from you if you get the chance.
2007-2009
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NOTE FROM EMILY WALSH
Greetings to all,
My, time certainly flies by! I am finishing my 4th year at Cornell already, and
yet, in some ways I feel as though I’ve been here even longer. I couldn’t ask
for better colleagues or students with whom to spend my time. Nor could I
ask for a nicer little town in which to live than Mount Vernon. Two years ago
my husband and I bought the house we had originally rented from Cornell
College, and we are slowly making it our own. We seem to spend most of our
time in the yard, feeding the birds, squirrels and rabbits, or planting gardens.
Over the past two years, I have developed several new courses, many of
them in cooperation with faculty from different divisions of the college. I
joined a Classics professor to teach a Geo-Archaeology course in Greece
during May, 2007, and I linked a First-Year-Only Physical Geology course
with an introductory Sociology course around the theme of Consumer Society. This linked course was a fascinating exploration of the consumption of
goods from both geological and sociological perspectives. The Sociology
Professor and I will reprise this linkage next year as a First-Year-Only Writing
Seminar. I also recently taught my first upper-level seminar entitled The Origin of Mountains, which I thoroughly enjoyed. Geology of the National Parks
was a blast last year in Hawaii but, perhaps due to our economic plight, it
had a low enrollment this year. To keep costs down, we are heading back out
to the Black Hills and Badlands of South Dakota (leaving tomorrow morning).
I have begun to find students who are interested in hard rocks, which has
led to several independent studies and summer research projects over the
past two years. We have been fortunate in our ability to travel to larger universities to use research instrumentation, such as the electron microprobe
and scanning electron microscope at both the University of Minnesota and
the University of Wisconsin, Madison. I was also able to take two students
with me to Tucson, Arizona, to use their laser-ablation inductively-coupled
mass-spectrometer to date zircons from the Norwegian rocks, and I continue
to work on several papers about the Norwegian ultrahigh-pressure rocks.
This summer I have the opportunity to travel to Xining, China, for a fieldtrip
conference and field work with new collaborators from Albion College and
Central Washington University. I have never been to China before, so I’m
really looking forward to that!
We have several new items of note in the Geology department, and we have
a great group of majors—it’s a good time to come back for a visit if you can!
We always look forward to seeing you.
Cheers,
Emily
S p a rk s F r o m T h e R oc k p i l e
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NOTE FROM RHAWN DENNISTON
Greetings from the Hilltop. I’m finishing my ninth year at Cornell, and one of my favorite
parts of being a member of the geology faculty has been getting to know department
alums. Please never hesitate to drop me a line and let me know what you’re up to.
My sabbatical year at the University of New Mexico was stimulating, rejuvenating, and
productive. Uninterrupted time at UNM’s Radiogenic Isotope Lab allowed me to wrap up
a few of projects that several students and I had toiled over for several years. One involved uranium-lead dating of an extremely well-preserved Miocene coral from the Dominican Republic. This project, which was initiated by Peter Cole (’05), showed the coral
to be 5.3 million years old, and marks the first time that a fossil has been directly dated
using traditional U-Pb techniques. This study was published in the journal Geology in
2008. I then used this coral to determine water temperatures for the Caribbean during
the Miocene, a project that Stephanie Penn (’04) worked on and that was published as a
chapter in a book called Evolutionary Stasis: Species and Communities through Geological
Time. Next up was a study of stalagmites from Nevada that grew during the early part of
the last glacial cycle, about 100,000-80,000 years ago. Brian Hoye (’05) and Charles
Trodick (’06) did a great deal of the initial work in this study which demonstrated that the
climate of the Great Basin of the western U.S. experienced rapid climatic changes in
concert with those observed in the Greenland ice cores. This study was published in
2007 in the journal Geology. Finally, I put the finishing touches on a project that Michelle DuPree (’03) did on a pair of Missouri stalagmites. These samples recorded two
intervals of aridity over the past 4,000 years, both of which are coincident with mobilization of sand dunes in Nebraska and at other sites across the Great Plains. This work was
published in the journal Quaternary Research in 2007. Several other students did great
work on other projects, as well, including Alyssa Borowske, Amanda Gibson, Emily Krauter, Diana Krogmeier, Mike Lommler, Abby Michaelson, Lara Moellers, and Kristyn
Rodzinyak.
I continue to plug away with attempts to reconstruct past climates from Portugal and the
Ozarks, but am now primarily focused on stalagmites from the Kimberley region of northwestern Australia, an area that gets most of its rainfall from the Australian summer monsoon but that experiences drought during El Nino events. Work on one 10,000-year-old
stalagmite by geology/art double major Rebecca Ellerbroek suggests that (1) monsoon
rainfall has been controlled on a century-by-century scale by fluctuations in the strength
of the Sun, and (2) extended droughts appear to have occurred during periods with numerous, intense El Ninos. I just received a $30,000 grant to continue this research and
am planning a trip to the Kimberley this June to collect additional samples.
I enjoy all of my classes, but none so much as my February field-mapping class in New
Zealand. One of these days, I’d love to take a group of alums there to show off one of
the most beautiful and geologically diverse landscapes imaginable. There aren’t many
places where you can stand at the base of a glacier with your feet on different tectonic
plates. If you’re interested, drop me a line.
Best wishes to you all,
Rhawn
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2007-2009
GEOLOGY OF NATIONAL PARKS : HAWAII : EMILY WALSH
In May 2008, the Geology of the National Parks course traveled to Hawaii for
a 2-week fieldtrip. Twelve students participated in the course led by Professor Emily Walsh with help from Sociology Professor Erin Davis. The first part
of the course was spent exploring the Big Island of Hawaii, and the final 5
days were spent on Oahu. Elevated activity of a new vent within Kilauea caldera sent an ominous plume up into the clouds and threatened to close Hawaii Volcanoes National Park and Kilauea Military Camp (where we stayed).
Other trip highlights included: green, black and tan sand beaches, lava tubes
and lava trees, pit crater hikes, sea turtles sunning themselves on the
beaches, waterfalls, and, of course, snorkeling. Professor Davis contributed a
relevant discussion about the history and present conditions of the Native
Hawaiian population—especially relevant in light of the miles and miles of
tent city that stretch along the SW coast of
Oahu. All in all the trip was a great success—
definitely one to do again!
S p a rk s F r o m T h e R oc k p i l e
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GEOLOGY OF NATIONAL PARKS: THE GREAT PLAINS : EMILY WALSH
In May 2009, the Geology of National Parks course explored two of the Great
Plains states, Nebraska and South Dakota. Opting for the low-budget plan, 6
students and Professor Emily Walsh rented a van and camped for the two
weeks, greatly enriching their field experience. After one week alone in the
field, the class was joined for a few nights by the Geomorphology class and
Professor Rhawn Denniston. Although the weather was up and down (snow
one day, ~90°F the next), the geology was spectacular. Highlights included:
the Sand Hills of Nebraska, Nebraska’s highest waterfall, hiking Bear Butte
in South Dakota, touring the Wharf Gold mine outside of Lead, SD, driving
down through the stratigraphic column as we entered the Black Hills, the
Needles in Custer State Park, lots of wildlife, and, of course, the Badlands
(the students’ favorite). The trip was highly successful, and, due to the relatively low cost to students and the visible, easily-explored geology, it will likely
become an alternate-year or every-third-year trip.
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2007-2009
GEOARCHAEOLOGY OF GREECE
In May 2007, Professor Emily Walsh accompanied Classics Professor John Gruber-Miller on a course trip to Greece. The combination of Geology and Archaeology worked extremely well, and
both instructors thoroughly enjoyed learning along with the students. Trip highlights included: several days in Athens to explore
the Acropolis, Agora and Kerameikos, the overnight ferry ride to
Crete, hiking the Samaria Gorge on Crete, hiking the peak sanctuary at Mt. Juktas (Crete) in a thick fog, the Corinth Canal, the
view from Acrocorinth, the theater at Epidaurus, wandering freely
through Mystra, the museums at Sparta and Olympia, the temple
at Bassae, Delphi, and the old silver mines at Laureion. Next
time we hope to include a
trip to Santorini as well!
S p a rk s F r o m T h e R oc k p i l e
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GEO CLUB SPRING BREAK TRIP 2008 : BIG BEND, TX : KELSEY FESER
The Geology Club's 2008 annual spring break trip took eleven Cornell students,
eight of whom were geology majors or minors, to Big Bend, Texas. After a short
flight and a grueling nine hour van ride, the group arrived at Big Bend National
Park, situated just north of the United States - Mexico Border. Our campground was located within a small rounded valley surrounded by mountains
(yes! there are mountains in Texas), which actually represent the ancient convergence of the Rocky and Appalachian Mountain ranges.
Throughout our daily hikes, we learned many more interesting geologic facts
about the park. We visited an old mercury mine, whose facilities were still
partially intact. Another day we took a hike to the Rio Grande and found sheer
cliffs hundreds of feet tall towering over the emerald green water. On one particularly memorable morning, a few of the more adventurous souls convinced
the rest of the group to wake up at 2:30 in the morning and hike the tallest
mountain in the park in order to make it to the top by sunrise. At Ernst Tinaja,
we encountered some of the most amazing evidence of metamorphic activity
(in the form of folding and faulting) any of us had ever seen.
There was also much wildlife to be seen. While spending an evening at a defunct hot spring bath, the group encountered one of the many species of water
snake. On the aforementioned early morning hike, several students spotted a
tarantula wandering across the trail, and at the campsite there were several
different types of birds and wasps.
All told, we had an amazing trip, and its one that many of us are still talking
about! We hope that the group can return to this site in the future and spend
even more time exploring this beautiful and geologically unique park.
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2007-2009
GEO CLUB SPRING BREAK TRIP 2009 : MOAB, UTAH : BECCA ELLERBROEK
Geology club teamed up with mountaineering club for an action-packed trip to Arches and
Canyonlands National Parks in Utah for Spring Break 2009. Twenty students filled six gearpacked cars and set off for Moab, Utah as soon we finished our final exams. Unexpectedly, a
spring blizzard over Vail Pass trapped us on the east side of the Rockies, so we stayed at a
very gracious club member’s home in Colorado Springs. We spent the first two days of our trip
grilling out, watching movies, and playing with the four family dogs.
Finally, the mountain pass opened, and we set off for Moab. We arrived via the stunningly
beautiful scenic route along the Colorado River, with sheer canyon walls looming on either
side. We set up camp at a Horse Thief campsite just a few minutes from Canyonlands National
Park. It was a chilly week in the high-elevation camp, but we stayed warm by bundling up and
cooking over a roaring campfire. On the coldest evenings, we drove into Moab for hot showers,
shopping, and delicious burritos.
On the first day, a few students rock climbed or mountain biked, but the majority of us explored Arches National Park. We hiked through fins and canyons to find Landscape Arch, Double O Arch, and the recently collapsed Wall Arch, among others. These sandstone arches were
formed because of a large underlying salt bed called the Paradox Formation. Salt is unstable
under pressure, which caused subsurface movement of the Paradox Formation, resulting in
the cracking, buckling, and shifting of the overlying sandstone. Over the years, water freezing
and thawing within those cracks shaped the beautiful arches, spires, and fins that we admired
in during our trip.
Over the next week, we hiked and climbed Arches and Canyonlands National Parks. We saw
Delicate Arch, of Utah license plate fame, and wandered the Fiery Furnace, a beautiful trailfree maze of looming red fins. We saw Ute petroglyphs and Wolfe Ranch, the homestead of a
19th Century settler. We visited the hotly debated Upheaval Dome, which is a curious 3 mile
wide circular area of deformed rock. There are
two possible theories explaining Upheaval Dome:
it may be an impact crater from a meteorite 60
million years ago, or it could be the result of a
massive salt bubble that uplifted and then collapsed.
The trip highlight was definitely Horseshoe Canyon. We drove nearly three hours to reach the
trailhead and descended 750 ft into the canyon.
On the way down, the ranger showed us several
different well-preserved dinosaur tracks! It was
the warmest, sunniest day of the trip, and we enjoyed a stunning view- the sheer canyon walls
loomed on either side of us, red rock with shining black desert varnish. Giant pictographs of
human figures are intricately depicted on the canyon walls. These larger-than-life stains are
perfectly preserved and are some of the oldest known rock art. Made by people predating the
Anasazi, the pictographs are at least 2,000 years old and possibly as old as 8,000.
Inclement weather over the mountain pass forced us to leave Utah early, and we spent another day or two in Colorado Springs. Despite our bad luck with the weather, everyone had a
wonderful and educational trip. Moab has more than excellent hiking- it has a fascinating
history and fantastic geology. It was also a great place to learn about conservation issues, as
the high desert climate is particular susceptible to human interference. We are extremely
grateful to Bill Cook for his generous gift, Student Senate for their funding, and the Kelly family
for hosting and feeding 20 kids through two snowstorms.
S p a rk s F r o m T h e R oc k p i l e
GEOLOGY MAJORS & MINORS 20082008-2009
2008 Majors: Jessica Preiss, Mike Quinn, Megan Regel, Kristopher Rhodes,
Adam Willett
2009 Majors: Ross Byerly
2009 Minors: Dana Friend, Abby Michaelson, Brad Wright
Student Awards and Honors
Herbert Hendriks Award (to the top senior geology major)
2008. Kristopher Rhodes
William H. Norton Geology Prize (to the top junior geology major)
2008. Kristyn Rodzinyak
2009. Kelsey Feser
Gene Hinman Geology Prize (for excellence in field research)
2008. Becca Ellerbroek
2009. Elizabeth Erickson
Hendriks Student Research Fund
2008. Kristyn Rodzinyak, Abby Michaelson
2009. Becca Ellerbroek, Kelsey Feser
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Page 15
2007-2009
STUDENT
RESEARCH
DANA FRIEND, ‘08
Skeletal Morphology of the Genus Millepora Displays Phenotypic Plasticity1, 4
MEGAN REGEL, ‘08
Zircon Geochronology from Migmatites and Pegmatites from the Western Gneiss
Region, Norway2, 4
Sector Zoning and Age in Zircon Grains from the Western Gneiss Region, Norway1
K R I S T O P HE R RH O D E S , ‘ 0 8
Paleobotanical Evidence for “Pluvial” Intervals in the Western Pangean Tropics During
the Early Permian1, 3
KRISTYN RODZINYAK, ‘08
Stability of Melt-rich channels in Earth’s Mantle: High Pressure and Temperature Experiments on Olivine, Chromite and MORB1, 2
MIKE QUINN, ‘08
Scanning Electron Microscope Study of Zircon Grains in Gneisses and Pegmatites from
the Western Gneiss Region, Norway1, 4
B E C CA E L LE R B R OE K , ‘ 0 9
Insolation, Enso, and Solar Controls on Northern Australian Moisture4
A B I G A I L M I C HA E LS O N , ‘ 0 9
Trace Elemental Analysis of a North Australian Stalagmite1
1 Presented
at Cornell College Student Symposium
2
Presented at North Central Geological Society of America Meeting
3
Presented at Geological Society of America Annual Meeting
4
Presented at Iowa Academy of Science Annual Meeting
S p a rk s F r o m T h e R oc k p i l e
Page 16
Skeletal Morphology of the Genus Millepora Displays
Phenotypic Plasticity
Dana Friend
The genus Millepora, commonly known as fire coral,
is a calcareous hydrozoan
common in tropical seas
worldwide. In the western
Atlantic, there exist two
prominent morphologies
that are presently being
classified as separate
species. Millepora alcicornis is defined by thin nodular branches; Millepora
complanata has plate like,
smooth blades. However,
recent genetic data suggest that the separate
morphologies exist because of phenotypic plasticity, and that two genetically isolated clades
(including an intermediate
form) cannot be distinguished from one another
morphologically. Quantitative analysis of coral colony microstructure using
thin sections, suggests
that it is possible to differentiate between M alcicornis, M complanata,
and the intermediate form
from each other morphometrically. However,
the distinctions aren’t
matched by the genetic
data, indicating that current described species of
Milleporids in the tropical
Western Atlantic are not
genetically isolated.
“A road cut is
to a geologist as
a $20 bill is to a
starving man”
John McPhee
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2007-2009
Zircon Geochronology from Migmatites and Pegmatites from the
Western Gneiss Region, Norway
Megan Regel
The Western Gneiss Region
of Norway is one of the
largest exposed regions of
ultrahigh-pressure (UHP)/
high-pressure (HP) metamorphic rocks in the world,
making it an excellent
location to study the tectonics of UHP metamorphism. During the Caledonian orogeny, nappes of
continental crust and
ophiolitic material were
emplaced onto Baltica
basement orthogneiss.
Migmatitic basement gneiss and pegmatites cutting the ophiolitic
nappes were collected west
of Trondheimsfjord to pinpoint the timing of the high
pressure event in that area.
Zircons were separated
from the samples, mounted
in epoxy, imaged by cathodoluminescence (CL),
and dated by laser ablation
multi-collector inductively
coupled plasma mass
spectrometry (LA-MCICPMS). A new technique
was used during the dating
process, decreasing ablation pit size to ~10 µm in
diameter and ~3 µm depth,
permitting the use of less
material and leading to
greater accuracy and precision of ablation. CL images
of the zircon grains generally reveal older igneous
cores containing oscillatory
and/or sector zones and
younger, lower uranium
rims; partially recrystallized grains contain remnant sector zones. Basement gneisses from the
area yield typical Gothian
ages of ~1600 Ma with
evidence of a Sveconorwegian event at approximately 950 Ma and little
sign of Scandian metamorphism. U-Pb ages of
zircons from migmatitic
basement gneiss; however, indicate that the
timing of partial melting
was associated with Scandian UHP metamorphism.
Pegmatite ages reveal
similar Scandian ages
with Ordovician protolith
ages.
“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
S p a rk s F r o m T h e R oc k p i l e
Page 18
Sector Zoning and Age in Zircon Grains from the Western Gneiss
Region, Norway
Megan Regel
Zircon is a strong mineral
capable of withstanding
extreme geologic pressures
and temperatures. It is able
to retain geochemical signatures, which allow the
timing of geologic events to
be determined. The Western Gneiss Region of Norway is one of the largest
exposed complexes of
ultrahigh-pressure metamorphic rocks in the world.
By determining the ages of
the grains, we can understand when in time the
rocks containing the zircons were at temperatures
and pressures high enough
to cause partial melting
and resetting of the U-Pb
ratio. Several of our zircon
samples show an original
core dated at ~1600 million years old with rims
dated to ~400- 420 million
years.
As a mineral
grows, it uses elements in
the vicinity; these elements then become depleted in the surrounding
area and cause chemical
zoning in the mineral.
Oscillatory zones are
extremely common in
minerals, especially those
with an igneous history.
Sector zoning is less common, as such, it is not
well understood. The
presence of sector and
oscillatory zoning in zircon
grains is often used to
interpret the geologic
history. The study of sector zoning in other minerals is used to understand
sector zoning in zircon in
this paper. The zircon
grains were imaged by
cathodoluminescence
(CL) to compare the pattern of zonation of each
grain with the spot age
location within the grain.
Zircon grains
were picked from nine
different rock samples.
Sector zoning and oscillatory zoning often occur
together; when they are
together they are often in
the grain core. The samples that contained the
most sector-zoned grains
were the migmatitic
gneiss and the granitic
gneiss. In the migmatitic
gneiss, 13 grains contained sector zones. Of
those grains, nine had
oscillatory zoning as well.
The granitic gneiss contained 25 zoned grains.
The basement rocks
(basalts) contain few
zircons and with the exception of a few outliers
contain no sector zoning.
Although there is a relationship between sector
and oscillatory zoning, the
two types generally occur
in different parts of the
grain. The core is usually
oscillatory zoned while the
rim is sector zoned. Sector zones are not found to
be correlative with age,
except where the sector
zones are located within
the cores of the grains.
Page 19
2007-2009
Paleobotanical Evidence for “Pluvial” Intervals in the Western
Pangean Tropics During the Early Permian
Kristopher Rhodes
The transition from
the Pennsylvanian to
the Permian in the
tropics of western
Pangea was marked
by a general trend
toward increased
temperature and
decreased soil moisture, based on geophysical indicators,
such as paleosol
morphologies and
oxygen isotopes.
Vegetation tracked
these changes and
there is a 1:1 correspondence of species pools with climate
proxies: floras dominated
by spore-producing plants
and primitive seed plants
characterize wetter-cooler
conditions, with floras
dominated by more derived
seed plants characterizing
drier-warmer conditions.
Taxa characteristic of wet
habitats, particularly tree
ferns and sphenopsids,
continue to appear sporadically during periods that
geophysical indicators
suggest were dry-warm,
possibly reflecting persistent wet sites on otherwise
more xeric landscapes.
However, during the middle
Artinskian, parts of the
Waggoner Ranch Formation of north-central Texas
are characterized by the
repeated recurrence of
tree-fern dominated floras
within an interval that in-
cludes xeric, seed-plant
dominated floras and
physical indicators of
warm-dry climates. There
are only minor, but noteworthy, overlaps between
these two species pools.
In several instances, the
wet floras occur in channel-form deposits suggesting short, “pluvial”
periods that did not leave
significant paleosol records. Considering the
close association of floral
composition and climate,
it can be inferred that
there were fluctuations in
soil moisture and possibly
temperature that permitted the short-term spatial
expansion of wetland
vegetation during the
Early Permian, probably
from populations persisting locally in sites marginal to water bodies.
These intervals of climate
oscillation further suggest
that glacial-interglacial
cycles, similar to those of
the Pennsylvanian SubPeriod, characterized Permian glaciations as well.
“There is a way that
land speaks. Most
of the time we are
simply not patient
enough, quiet
enough, to pay
attention to the
story.” -Linda
Hogan
S p a rk s F r o m T h e R oc k p i l e
Page 20
Stability of MeltMelt-rich channels in Earth’s Mantle: High Pressure
and Temperature Experiments on Olivine, Chromite and MORB
Kristyn Rodzinyak
Melt transport, the movement of molten rock
through the Earth’s relatively solid outer shell, is
important in many geological processes. Volcanism at
subduction zones and hot
spots and the formation of
oceanic crust at mid-ocean
ridges all involve melt
transport. To increase our
understanding of how melt
moves from depth to
Earth’s surface, we conducted experiments at high
temperature and pressure
on fabricated rock samples
of modeled mantle rock
compositions.
We deformed these rock
samples, containing olivine
and chromite and 4% mid-
ocean ridge basalt, at a
constant twist rate at
experimental conditions
of 1473 K and 300 MPa.
These conditions are
comparable to the temperature, pressure and
stress conditions experienced by rocks within
Earth’s mantle and at
which melt segregates or
separates into layers. In
our experiments, the
samples were then exposed to a 4-hour static
anneal at 1473 K and
150-200 MPa to cause
the melt from the meltrich layers to dissipate
and redistribute homogeneously. Our observations
demonstrate that surface
tension is an important
factor in melt redistribution when a stress is no
longer present. These
small scale experimental
results, obtained on cylindrical samples a centimeter in diameter, can be
scaled to the sizes appropriate for Earth processes, helping to expand
our knowledge of how the
Earth removes heat from
within by transporting
melt in channels from the
mantle to the surface.
NASA sponsors this research because a solid
understanding of Earth
processes helps us understand similar processes
on other planetary bodies.
Page 21
2007-2009
Scanning Electron Microscope Study of Zircon Grains in Gneisses
and Pegmatites from the Western Gneiss Region, Norway
Mike Quinn
Metamorphic rocks,
gneisses and pegmatites,
from the Western Gneiss
Region in southwestern
Norway were analyzed to
determine when the area
was metamorphosed at
ultrahigh pressures during
the Caledonian orogeny.
Cathodoluminescence
images (CL) of zircon grains
separated from the samples show older oscillatoryzoned igneous cores and
younger metamorphic rims.
The zircon samples were
analyzed using a Laser
Ablation Multiple Collector
Inductively Coupled Plasma
Mass Spectrometry (LA-MCICP-MS) to determine the
age of metamorphism.
Multiple miner-
als are included within the
zircon grains used for CL
and LA-MC-ICP-MS.
Shape, size and elemental composition of the
inclusions were analyzed
using a scanning electron
microscope (SEM). The
shapes and sizes of the
inclusions varied, however the colors of the
inclusions are all dark
except for monazite,
which is white. From this
data specific minerals
were identified. The location of each mineral inclusion was also compared
to the chemical zonation
of its host zircon grain to
determine what role the
mineral inclusion played
in the growth of the zir-
con. Results show that
quartz and apatite inclusions are commonly
found in the oscillatory
core of the zircon, suggesting that the minerals
were included during the
growth of the zircon from
a magma. For the monazite inclusions, they were
commonly found near the
border of the core and the
metamorphic rims suggesting that the minerals
were included a later
growth.
S p a rk s F r o m T h e R oc k p i l e
Page 22
Insolation, Enso, and Solar Controls on
Northern Australian Moisture
Becca Ellerbroek
This research presents an
oxygen and carbon isotopic
time series from a Holocene stalagmite from the
Kimberly region of northwest Australia. Twenty-six
U-Th dates reveal stalagmite deposition from 8.7 to
4.0 ka, interrupted by 13
short-lived hiatuses.
Growth ceased entirely
from 4.0 –0.7 ka, at which
time deposition resumed
for approximately 100
years. These hiatuses correspond to peaks in El Niño
activity suggesting that this
stalagmite may serve as a
sensitive recorder of ENSO.
Carbon isotopic trends
correspond well with solar
irradiance, as reconstructed via ∆ 14C records.
Today, regional rainfall
oxygen isotopic variability
is closely tied to the
amount effect, and thus
we interpret shifts in
stalagmite δ18O values
throughout the Holocene
as changes in the intensity of the Australian summer monsoon, and are
well correlated with austral summer insolation.
“(In geology) we find no
vestige of a beginning –
no prospect of an end..”
James Hutton
Page 23
2007-2009
Trace Elementall Analysis of a North Australian Stalagmite
Abigail Michaelson
A 152 cm tall stalagmite
(KIM1) was collected from
the El Niño-Southern Oscillation (ENSO)-sensitive and
monsoon-dominated Kimberly region of northwestern Australia. In order to
better constrain the results
of a previous a stable isotope study of KIM1, we
conducted 173 trace elemental analyses at 1 cm
intervals, corresponding to
~20 year resolution. Mg/Ca
and Sr/Ca ratios were
covariant both with each
other and with carbon
isotopic ratios for most of
the growth interval (~88004050 yr BP), and like the
carbon isotope record,
were roughly antiphased
with oxygen isotopic ratios. One exception is the
period 5500-5000 yr BP
during which time the
Mg/Ca and Sr/Ca ratios
deviated from the carbon
isotopic ratios and appeared instead to correspond with oxygen isotopic ratios. A lag between
peaks in reconstructed
ENSO activity and Mg/Ca
and Sr/Ca ratios is also
apparent.
“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