Wednesday, December 28, 2011

Localized Glaciers in the Eastern US

Here in the eastern USA there are some signs of localized glaciation, mainly in New England. Of course almost everyone is aware of the huge continental glaciers that once covered much of North America and which is now isolated in Greenland on our continent.

Katahdin, Maine's highest summit.

What has always intrigued me are the smaller local glaciers that were left behind when the huge ice sheets retreated. As the higher elevations of New England were revealed from beneath the melting ice, there were still some areas just high enough and just far enough north to have localized glaciers that spilled off of some few peaks, creating glacial cirques and leaving behind glacial moraines and making tarns on some of the high ridges.

The first place I ever went that had obvious signs of local glaciers was Mount Katahdin. The rivers of ice that carved out the enormous gulfs and soaring cliff faces are long gone, but if you know what you're looking at, it's obvious what forces created these features.

I've now hiked in several eastern glacial cirques, including some on Katahdin in Maine and two on Mount Washington in New Hampshire. These peaks stand 5,268 feet and 6,288 feet respectively, and so were able to retain local glaciers for a long time after the retreat of the continental ice sheets that had covered the north.

Here in the South there is almost no sign of localized glaciation. But although the enormous ice sheets never reached this far toward the equator, some of the peaks should have been able to spawn some local glaciers. After all, there are many peaks here in Tennessee and North Carolina and southern Virginia where elevations approach or exceed 6,000 feet above sea level. Surely conditions should have been right for local glaciers on some of these peaks.

Arrows indicating the two most obvious glacial cirques on Katahdin (from this perspective). Known locally these days as 'Gulfs'.

However, in my reading and research I have found that only one spot has enough evidence for such a local glacier. And that spot is on Grandfather Mountain (aka Tanawha) here in North Carolina. Grandfather/Tanawha is considered the highest peak in the Blue Ridge Mountains. At 5,964 feet above sea level, it's not even in the top 20 highest peaks in the east. However, it just misses being an official "sixer" and looks more like a peak in the Sierras than one on the Blue Ridge. If any southern peak could have spawned glaciers, it seems that this would be it.

Today, there is a formation on the mountain called "the Boone Bowl". This bowl was likely carved out of the mountain by a small river of ice that formed below the summit and etched its way down the slopes, creating the enormous natural amphitheater the locals call "the Boone Bowl". I hope to be able to go there and scout it out in the next few weeks, and produce some photos that indicate some similarities with the glacial cirques I've hiked on Mount Washington and Katahdin.

We'll see.

Possible view of the "Boone Bowl" (Photo copyright by grouchomark)

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