Hope Professor Sifts Through Sand Dune History
Posted May 19, 2003
HOLLAND -- A Hope College professor is taking the
long view of sand dune movement, tracking the way they've
behaved for the past 5,000 years.
"The basic idea is to find out when the dunes
began to form; find out when they were active -- in other
words, when were they growing and moving; and find out when
they were stable -- when they were sitting in one place," said
Dr. Ed Hansen, professor of geology and environmental
science and chairperson of the department. "And eventually
to try to figure out why they're sometimes active and
He is interested in the topic as a research
question, but he also appreciates the practical benefits of
better understanding the dunes' behavior. "If we've got an
idea of what the natural history is, it would be easier to
manage them," he said.
Hansen recently received support for his research
through a $50,000 grant from the Petroleum Research Fund.
The grant will provide stipends for Hope student
researchers, laboratory testing and materials for the next
Hansen has been studying the dunes in the Holland
area since 1998.
"We now have worked out a really detailed history
around Holland," he said. "We probably have one of the most
detailed histories of a dune complex ever worked out."
Through the new grant, he will choose four or five
other sites along the eastern coast of Lake Michigan to
develop a more complete view. "When we're done we should be
able to generalize--to have a general dune history--for the
southern part of the lakeshore, for the area roughly from
Muskegon south," he said.
According to Hansen, the dunes formed about 5,000
years ago. The lake prior to that time had been much lower
than it is today. It subsequently rose to a height several
feet higher than its present level and then fell quickly,
which is when the dunes developed.
In the Holland area, he noted, the more inland
dunes stabilized and became forested, as they still are,
about 4,000 years ago. The dunes closer to shore were
fairly fluid until about 2,000 years ago, at which time they
became stable for some 1,500 years.
The dunes locally started shifting again about 500
years ago, behavior that continues. Hansen and his team
have tracked one area shore dune moving inland at a rate of
about 4.5 feet per year.
Hansen notes that researchers don't yet know what
prompted the times of stability and movement. "We would
love to know why," he said.
One implication, however, is clear: the
phenomenon of dune movement isn't man-made. "Certainly some
of the things we do may enhance it, but it started before
any Europeans came and cut down the first tree or someone
rode the first off-road vehicle," he said.
To map the history of the shoreward dunes, Hansen
has charted tell-tale signs in the sand: visible lines of
dark soil that run horizontally through today's dunes.
"What they are is the top soil, essentially, of a former
surface of the dune," he said. Radio carbon dating helps
determine the age of the former surfaces.
For the wooded back dunes, where former surface
soils are hidden, he and his team do some digging to collect
soil samples, and have another form of testing done to
determine how long the sand has been buried: optically
stimulated luminescence, a new technique that essentially
reveals how long the sand has been out of the sun.
Hansen is conducting his work on dune history in
collaboration with Alan Arbogast of the Michigan State
University faculty. He is also engaged in another project
that looks at more recent dune behavior, work that he
conducts with Deanne van Dijk of the Calvin College faculty.
He has made multiple presentations at professional
conferences concerning his research. During the 2003 annual
meetings of the Michigan Academy of Science, Arts and
Letters, held at Hope in March, he led a special session on
"The Geology and Geomorphology of the Lake Michigan Coast"
that included a trip to the area dunes and presentations by
specialists from Michigan, Indiana, Wisconsin and Canada.