Geologists Duane and Ruth Braun PHOTO COURTESY OF DUANE BRAUN

MDI geological puzzle subject of joint speech



SOUTHWEST HARBOR — Geologists Duane and Ruth Braun will speak twice about the geological makeup of Mount Desert Island at the public library here on Tuesday, Aug. 25, once at 5 p.m. and again at 7 p.m. Advance registration is required.

The Braun’s talk will begin around a billion years ago when MDI was attached to the super continent Gondwana. It eventually split from Gondwana and attached itself to North America. MDI itself experienced three major geologic events which resulted in the formation of 10 different rock units that now make up MDI. The oldest of these formations is the beautiful Ellsworth schist.

Most of the rock on MDI formed around 420 million years ago as magma intrusions fed a huge volcanic crater the size of MDI. Two miles of rock have been eroded since then to form the present landscape. Over the last 2.5 million years, glaciers have repeatedly covered the island with up to 5,000 feet of ice. When the glaciers retreated, they left behind a number of different deposits and landforms helping to create a beautiful and striking landscape.

Ruth Braun earned her master’s degree from Johns Hopkins University. She has taught science, math and geology courses in a variety of high schools and universities.

Duane Braun earned his doctorate from Johns Hopkins University. He was the geosciences professor at Bloomsbury University. He also mapped the glacial deposits of a 9,000-square-mile area of northeastern Pennsylvania for the Pennsylvania Geology Survey.

Both Brauns have been instructors for Acadia Senior College. They currently are assisting with the revision of the geologic maps of MDI for the Maine Geologic Survey as well as writing the Geology Guide of MDI for the 2016 Acadia National Park Centennial.

To reserve your seat, call the library at 244-7065.

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