May 20, 2018
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Maine Geological Survey publishes Baxter book

Contributed | BDN
Contributed | BDN
The Maine Geological Survey has published a new book on the geology of Baxter State Park, titled, ?A Guide to the Geology of Baxter State Park and Katahdin,? by Douglas W. Rankin and Dabney W. Caldwell. The new book has a number of new features, including two full-colored maps and a de-scription of five geology hikes in the park. PHOTO: COURTESY OF THE MAINE GEOLOGICAL SURVEY

AUGUSTA, Maine — Baxter State Park and Mount Katahdin have long been treasured for their wild beauty and the outdoor recreational opportunities they offer visitors.

A new book published by the Maine Geological Survey is unearthing a neglected aspect of the state park and its iconic mountain — its geology and the continent-moving forces that went into creating this unique part of Maine.

Through a collaborative effort, “A Guide to the Geology of Baxter State Park and Katahdin” by Douglas W. Rankin and Dabney W. Caldwell completely revises an earlier bulletin on the same subject, according to a press release from the Maine Department of Conservation.

The new book includes new information about Baxter State Park based on the latest understanding of plate tectonics and continental glaciation; two full-color maps on bedrock and glacial geology; photos that give a feel for the park area; sidebars on history, science and geology; and a description of five geology hikes ranging from easy to challenging.

“It’s such a popular area and our old publication was so out of date, it was crying out to be done,” Dr. Robert Marvinney, Maine state geologist and director of the Maine Geological Survey, which is part of the Maine Department of Conservation, said. “We wanted to improve it and not just take the old one and update it. We wanted to make this fantastic landscape and geology accessible to a broader audience.”

Famous for such reasons as being a terminus of the Appalachian Trail and for its unique Alpine ecology, Katahdin and the 209,501-acre park often are overlooked from the geological perspective.

The park is a large area of igneous intrusions and volcanic rocks, featuring solidified molten granite pushed up from below in a gigantic eruption to form the mountain, later carved out by glacial activity, in the southern part of the park, and sedimentary rocks, specifically in the north part of the park, that contain numerous fossils, including Maine’s state fossil, Pertica quadrifaria, a primitive plant.

The area was first surveyed in the 1830s by J.W. Bailey and Dr. C.T. Jackson, who concluded much of the Katahdin landscape was caused by “Noah’s Deluge,” or the biblical flood. It was Caldwell, a noted Harvard-trained Maine geologist, who studied and wrote the first definitive edition of the guide in 1960, last updated in 1972, Marvinney said.

After Caldwell’s death in 2006, it was decided to revamp the guide once again, and Rankin, another internationally noted geologist with the U.S. Geological Survey, who mapped much of the volcanic rocks, was invited to participate in the project, Marvinney said.

“A Guide to the Geology of Baxter State Park and Katahdin” is $10, plus tax, and can be purchased by calling the Maine Geological Survey at 287-2801. For more information visit

Robert Tucker, MGS director of earth resources information, said that a real effort was made to make the guide more popular and something “that someone with a general science background could read.” The information director, who designed the book, said he used the format of the geology books published by the National Parks Service and coordinated photos, text and maps in a three-column format on the same page.

MGS geologist Henry Berry, who edited the bedrock section, pointed out several notable features of the park, saying, “The reason everyone goes to Baxter State Park is because it is a great park to be in, a great expanse of undisturbed land that you can explore and find the context of things.”

Among those notable features are the high peaks of the Katahdin area, he said. “The mountain is there because the type of granite near the top is more resistant to erosion,” Berry said. Some of this granite, which forms an enormous oval shape about 40 by 22 miles, is thought to be about 3 miles thick in places.

He also pointed out that there is a huge area of ancient volcanic rock that makes up the Traveler Mountain area near the northern access of the park. This “world-class” area is mountainous specifically because of the type of volcanic rock, called Traveler Rhyolite, a flinty rock that can have razor-sharp edges.

In contrast, the far northern area contains marine sedimentary rocks, specifically sandstone containing fossils, which are more easily eroded, Berry said. Hence, the area is a lowland, including Lake Matagamon, he said.

MGS geologist Thomas Weddle, who worked on the surficial geology of Baxter State Park, said it was challenging to bring Caldwell’s views in line with modern concepts about glacial erosion. Two interpretations regarding the formation of Katahdin’s Great, North and South basins are presented.

Caldwell suggested there were active mountain glaciers in the basins after the Great Ice Sheet, between 25,000 and 13,000 years ago. Glacial geologist P. Thompson Davis, a professor at Bentley University, Waltham, Mass., who did graduate work on the park, instead has said that the last glacial activity at the basins was in fact the ice sheet, Weddle said.

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