The Geology of Baxter State Park and Mt. Katahdin

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

It has been mentioned that studies of glacial geology in other parts of the world indicate that there have been several, probably four, major episodes of continental glaciation in the past one million years, and that present climatic conditions are part of the waning stages of the last major glaciation which probably began about 30,000 years ago. Nearly all of the glacial deposits in New England are a product of this last continental glacier, but it is difficult to determine for any particular area when this glacier finally melted. It would be safe to say, however, that the last continental glacier to cover the Baxter State Park area was here somewhere between about 9,000 and 15,000 years ago.

Figure 16

The erratic boulders near the summits of many of the mountains in Baxter State Park were left by the last continental glacier, although most moraines of similar material have been removed from the valleys by stream erosion. However, just east of the Basin Pond moraine is a smaller belt of moraines which, because of the boulders and cobbles of sandstone and other erratic material in them, probably were formed by a continental glacier. The Basin Pond moraine, on the other hand, is composed almost entirely of Katahdin granite, which indicates that it was formed by valley glaciers which had only bedrock sources of Katahdin granite available to them. Because the Basin Pond moraine extends more than a mile south of the cirques which produced the valley glaciers, these valley glaciers likely ran into the mass of continental ice and were carried southward by it. An attempt to reconstruct the distribution of the glaciers at this time is shown in Figure 16.

Other evidences of the last continental glacier in Baxter State Park are the stratified drift deposits and meltwater drainage channels of the till, principally in the South Branch Pond area.

Small valley glaciers lingered in the cirques on Mt. Katahdin following the final melting of the continental glacier. The present rugged landscape of Mt. Katahdin, including such features as the Knife-Edge and the steep headwalls of the cirques, was formed by erosion by these valley glaciers. Much, if not most, of the erosion represented by the cirques themselves was performed by the combined efforts of older valley glaciers which accompanied older continental glaciers. The most recent erosion, however, which produced the Knife-Edge and other details of the landscape that we see today, is the result of the latest valley glaciers to occupy the cirques. The presence of moraines associated with these cirques indicates that there may have been several periods of stable climate following continental glaciation, although in general the climate has become warmer following continental glaciation. Because no evidence has been found by which the beginning or, indeed, the end of the valley glacier stages can be dated, it is not known for how long valley glaciers lingered in the cirques on Mt. Katahdin. The relatively unweathered condition of such moraines as Blueberry Knoll compared with the deeply weathered Basin Pond moraine suggests a long time, perhaps several thousands of years, elapsed between the formation of these moraines.

Valley glaciers did not form in most of the valleys in the Traveler Mountain area following continental glaciation, apparently because there was not sufficient elevation. It is interesting to note that several geologists have interpreted the evidence on Mt. Washington in New Hampshire to mean that no important valley glaciers existed on that mountain following continental glaciation. Lack of prominent moraines in the cirques and the relatively subdued appearance of the cirque headwalls on Mt. Washington indicate that the cirques probably were formed during some older stage of glaciation; that the cirques were overridden by the ice sheet and somewhat eroded, and that important valley glaciers were not present after the ice sheet melted.

The pile of rubble at the had of North Basin is probably the youngest glacial feature in Baxter State Park and may have formed during a period of several hundred years preceding the mid-nineteenth century. Since about 1850, glaciers in many parts of the world have been melting, whereas during the five hundred or so years which preceded 1850, glaciers advanced in the Alps and other mountain regions.

Introduction Bedrock Glacial geology Geologic features Acknowledgments Glossary References Plates

Last updated on January 11, 2008

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The Geology of Baxter State Park and Mt. Katahdin

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