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Tapping Into the Secrets of Maine's Coast

Story posted July 05, 2005

students examine rocks

The rocky shores of the Maine coast famously are associated with the glaciers that carved their way through the area 25,000 years ago, exposing and carving beautiful layers of granite and schist.

Look back 400 million years earlier, says Associate Professor of Geology Rachel Beane, and you see something quite different - volcanoes.

Beane is conducting research on the volcanics that covered what is now Casco Bay. Although geologists have long suspected the presence of volcanics - rocks produced by volcanoes - little is known about the type of volcanoes that were active here, or their location off the present-day coast.

Working with groups of students, Beane has collected roughly 100 samples of rocks from Portland through Phippsburg. The samples are analyzed for their geochemical elements to try to determine their specific type of volcanics.

"Our coast has many different rock formations and several of those formations started out as volcanics," explains Beane. "They have since been metamorphosed - changed due to temperature and pressure. We're trying to see through the metamorphism to determine what was there originally.

"It may tell us a little more about the evolution of the Earth and even help us to understand what's happening now in active volcanic arcs, such as the Alaskan Aleutian Islands and Japan."

Beane is aided in her work by tectonics - continents and oceanic plates driven together by subduction forces. "Walking on the Maine coast, many of the rocks seem to be standing straight up," she says. "Originally they were flat but were pushed up by tectonics. That allows you to see many layers that wouldn't normally be visible.

"The granite we see on the coast ... was magma that cooled underneath the surface of the earth. We also can see sediments, some of which collected on the ocean floor and some of which ringed the volcanoes themselves. "

Some of Beane's student researchers have analyzed samples using Bowdoin's optical and scanning electron microscopes, while others are gaining fieldwork experience.

"My students learn how to wield a sledgehammer," grins Beane. "Some learn how to use a rock saw. If I'm going to teach and mentor students in what I do, I'm going to bring them fully into my research. It's great to see how much students learn when you put knowledge into a real context."

Beane's research is funded, in part, by a grant from the National Science Foundation.

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