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Home > Explore! > Bedrock Geology > Baxter State Park > Glacial Geology

The Geology of Baxter State Park and Mt. Katahdin

Glacial Geology

The record of the geologic history of Baxter State Park between the Devonian Period and the Pleistocene or Glacial Period, which began about one million years ago, is for all practical purposes blank. Probably for at least 99 percent of the approximately 350 million years between the Devonian Period and the Ice Age the area under consideration was out of water and no bedrock younger than Middle Devonian in age has been found. During this great span of time, streams and rivers slowly eroded the bedrock formed during the Lower Paleozoic Era, carrying it away to the ocean as gravel, sand, and mud. Perhaps as much as 10 thousand feet of rock was eroded.

The harder, more resistant types of bedrock were eroded more slowly than the softer rocks. The igneous rocks, Katahdin granite and Traveler rhyolite, being more resistant, form the mountains in Baxter State Park; whereas the softer sedimentary rocks have been reduced by erosion to low hills. The general features of the landscape are the result of erosion of different types of bedrock. The mountains are high because they are formed of more resistant bedrock types and the lowlands are low because the bedrock in these areas consists of weak sedimentary rocks.

The present elevation of Mt. Katahdin and the other mountains in Baxter State Park above the surrounding lowlands represents the result of nearly 300 million years of erosion probably attained during the Middle or Late Cenozoic Period, but before the Ice Age. The landscape in the Katahdin area at the beginning of glaciation was approximately that of today and the results of glaciation have merely modified the preglacial landscape.

The answer to the often asked question, "How old is Mt. Katahdin?" must be given in three parts. In the first place, the rocks which form the mountain are old, about 360 million years old. Secondly, the general shape of the mountain, and especially its relief above the lowlands, is the result of a long period of erosion and was probably attained in essentially its present form about 2 to 5 million years ago. And finally, the details of the landscape, such as the Knife-Edge, the basins on Mt. Katahdin, and many features of the streams and rivers, are the result of glaciation which occurred during the past one million years.

It is tempting to speculate about what might have happened in the Katahdin region during the nearly 300 million years of its unrecorded history. But even though comparisons could be made with other parts of the world which have records dating from these years, the result would be a story bordering upon science fiction. The record of glaciation in Baxter State Park, however, is well preserved and is the subject of the following section of this paper.

Glaciers and how they form

Results of glaciation in Baxter State Park

Sequence of events inferred from the glacial geology of Baxter State Park

Introduction   Bedrock   Glacial geology   Geologic features   Acknowledgments   Glossary   References   Plates

Last updated on January 11, 2008