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Using
echo-sounding
equipment to create images and maps of areas below the ocean floor,
researchers
have begun to unravel a new story about the Antarctic Ice Sheet. Images of areas
below the Changes in Most studies of
the
"greenhouse to icehouse transition" –– a time of
climatic change that
occurred about 35 million years ago –– deal only
with ice sheet growth on "We know that
West Antarctica is the most sensitive of the ice sheets and most likely
to
respond adversely to global warming," commented Bruce Luyendyk,
professor
of marine geophysics and Earth science at UC Santa Barbara, and
co-author of a
paper describing the study in the May issue of the journal Geology. Much of the
bedrock
of The scientific
team
believes that West Antarctica was previously higher in elevation, and
that
large glaciers extended offshore into the The scientists
used
seismic reflection imaging, a type of echo-sounding that shows
structures
hundreds of meters beneath the ocean floor. The images depict
geological
structures underneath the "These seismic
reflection profiles image U-shaped, erosional troughs that are
interpreted as
having been carved by glaciers, and flat-topped ridges, that are
interpreted as
giant moraines," said first author Christopher C. Sorlien, a research
scientist at UCSB. Moraines are large mounds of sediment that have been
deposited by moving glaciers. These features
mapped below the sea floor look like formations carved and deposited by
glaciers elsewhere. "We can see that ice was carving up the continental
shelf soon after the greenhouse to icehouse transition," said Luyendyk.
"These look like geological features that were formed by moving ice." This evidence for In addition to
Sorlien and Luyendyk, other co-authors from UCSB are Douglas S. Wilson,
an
associate research geophysicist in the Department of Earth Science, and
Robert
C. Decesari, who was a research assistant in the same department and is
now a
senior petroleum geologist with Exxon Mobil. Louis R. Bartek, associate
professor in the Department of Geological Sciences at the ##
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