Where Ice Sheets Meet
Aaron Putnam of Chapman, Maine, spent two months as part of a
four-person expedition studying the stability of the West Antarctic
Ice Sheet. From their base camp in a remote area called the
Bottleneck, the scientists made daily excursions, rappelling into
ice moats and scaling sheer cliffs to collect rock samples.
Photo courtesy of Aaron Putnam
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Last winter, University of Maine
master's student Aaron Putnam was in the TransAntarctic Mountains on an
expedition that included some extreme rock collecting. He and members of
a research team rappelled into wind-carved ice moats, scaled sheer
cliffs and chipped away at boulders, looking for clues about the
stability of the two ice sheets that cover Antarctica.
Their camp was in the Bottleneck, a critical junction between the East
and West Antarctic ice sheets. Ice flows through this gap from east to
west between the mountains. What scientists have yet to understand is
whether ice on the west buttresses ice on the east. If it does, the
Bottleneck could provide the only major passageway from one side of the
continent to the other.
Furthermore, the fates of the two ice masses would be linked. The West
Antarctic Ice Sheet is smaller and more vulnerable to collapse because
it sits on bedrock below sea level. If rising seas caused it to
disintegrate, scientists wonder what would happen to ice on the eastern
side of the mountains. Could enough ice flow through the Bottleneck to
destabilize the East Antarctic Ice Sheet?
Part of the answer may lie in the rocks that Putnam and his team
collected. At the height of the last Ice Age, Antarctic ice bulged
through the mountain gap and, as it receded, left behind so-called
"bathtub moraines," rocks and boulders layered in rings on the
surrounding mountains. By determining when they were deposited, the
scientists hope to define when and how high the ice crept up the
mountainsides, and how much the level of the ice has declined since
then. That information could help determine if the Bottleneck serves as
a wide open valve for east Antarctic ice or if ice flow is limited by
the shape of the bedrock and surrounding mountains.
With Putnam on the expedition were Robert Ackert and Sujoy Mukhopadhyay
of Harvard University, and mountaineer Peter Braddock. UMaine emeritus
professor Harold Borns helped plan the expedition; Brenda Hall,
assistant research professor in the Climate Change Institute, is
Putnam's adviser. Support came from a $130,135 National Science
The researchers shipped home about 1,000 pounds of rocks, most of them
to Harvard, where they will be analyzed with cosmogenic dating to
determine when the rocks were first exposed at the Earth's surface. As
soon as rock is exposed to the sky, it is hit by cosmic rays that cause
chemical changes in the minerals. These changes create by-products,
forms of beryllium, neon and helium, for example. Just how much of these
by-products have accumulated provides an indication of how long the
rocks have been exposed.
At UMaine, Hall is setting up a lab to conduct cosmogenic dating on the
rocks that Putnam sent to Orono. For his thesis in geology, Putnam is
focusing on how the rock deposits may indicate how the climate in the
Bottleneck region has changed over time.
New plants for Maine's cold climes
Landscape horticulture graduate student Ajay Nair is experimenting
with ways to cultivate the ornamental Japanese stewartia in colder
climes like Maine.
Japanese stewartia is a landscaping
tree coveted for its year-round beauty. In the winter, it shows off its
multicolored, textured bark. Its summertime blooms look like camellias,
and its fall foliage features shades of yellow and red. The biggest
drawback for Maine gardeners: Stewartia grows best in USDA Hardiness
Zones 6–8. Maine has Zones 3–5.
Researching ways to propagate stewartia in this state is the thesis
project of graduate student Ajay Nair, part of ongoing collaboration
among the University of Maine, an alumnus, and Maine's ornamental
horticulture industry. Nair works with UMaine Associate Professor of
Horticulture Donglin Zhang, whose research involves developing new
plants to benefit Maine's horticultural industry.
Growing plants in Maine has many challenges, particularly their ability
to overwinter. That's why the extensive cold hardiness research going on
at UMaine is so important. For instance, recent cold hardiness studies
demonstrated that five cultivars of mountain laurel and more than 20 of
Atlantic whitecedar can be grown in Zone 4 in central Maine. Such
research provides technical guidance for growers and increased consumer
Nair and Zhang are working with one cold-tolerant clone named Stewartia
UMaine (UMaine Silk Camellia), which has been growing well at the
university's Littlefield Ornamentals Trial Garden. The tree has
brilliant red fall color and biennial flowering. Nair has been
experimenting with different rooting media and propagation techniques
using seeds, tissue cultures and stem cuttings. He coauthored a paper,
with Zhang and graduate student Dongyan Hu, on the rooting and
overwintering of stewartia stem cuttings that won first place in the
graduate student and presentation competition at the Northeast Regional
Meeting of the American Society for Horticultural Science in Washington,
D.C. earlier this year.
"We hope to answer questions about propagation, especially the
conditions needed for cuttings, so stewartia is easy to cultivate and
more commercially viable," says Nair of the nonnative yet noninvasive
The three researchers have used DNA markers to determine the
relativeness of Stewartia UMaine to 16 named Stewartia taxa. Working in
cooperation with colleagues at Harvard University's Arnold Arboretum,
the researchers found that Stewartia UMaine is a new cultivar that
originated from a gene pool of S. pseudocamellia, S. sinensis and S.
koreana. These molecular results will be used as guidance for future
Stewartia breeding. Their paper on the discovery won third place in the
national graduate student poster competition at the annual American
Society for Horticultural Science conference in Las Vegas in July.
Nair, who came to UMaine last year from Kerala Agricultural University
in India, also works with University of Maine Cooperative Extension
Ornamental Horticulture Specialist Lois Stack on experiments with phlox
and rubeckia. They are investigating the effectiveness of plant growth
regulators in preventing powdery mildew diseases, which can cause
significant losses to growers each season.
Horticulture, including floriculture, is the fastest-growing sector of
American agriculture. In 2003, Maine ornamental plant sales were valued
at $100 million. Maine horticulture includes more than 780 firms,
employing more than 10,000 people.