A Layer of Ice Shielding Infinite Layers of History

From May to November you can find Fort Ticonderoga bustling with the sounds of history. Often, you will witness the flash of musketry, the march of soldiers and the echoing of the Fife and Drum Corps. It is hard to fathom that on a white, wintry day like today, it is quiet enough to hear the branches of trees dripping with melting snow and the subtle winds whirling through the Champlain Valley—a perfect opportunity to ponder the history of the land far before the fearless acts of heroism took place on this battleground—lands which are rich in agricultural, forest, and biological resources. It’s hard to believe that just 550 million years ago (remember that Earth had already been around for roughly 4 billion years by this point), the eastern edge of proto-North America was covered by the Iapetus Ocean. If you were to place yourself where our museum campus is now, rather than witnessing the majestic, tall Adirondack Mountains to your west, and vast Green Mountains to your east, you instead might find the extensive formation of sedimentary layers resulting from the slow deposition of sediments, precipitates, and fossil remains.

Champlain Valley when ADKs formed

The proto-Champlain Valley is pictured in the center as a long chain of hills, derived from a major fault known as the “Champlain Thrust”. The main metamorphic rocks of the Green Mountains are to the east, the land to the west captures the uplift and development of the steeper topography of today’s Adirondack Mountains.

Over time, this slow accumulation of sediments is interrupted by ruptures of tectonic activity. The initial formation of Vermont’s Green Mountains occurred through orogeny (a mountain-building process brought about by plate tectonics) about 450 million years ago, as a smaller entity of the formation of the entire Appalachian chain. Only a mere 20 million years ago—what seems like yesterday—the Adirondacks we know begin to make themselves known through the uplift and exposure of buried metamorphic and indigenous rock that date over a billion years old (hence why they are referred to as “new mountains from old rocks”). During this time, we can stand back on the museum campus grounds and see the beginnings of our dome-shaped Adirondacks to the west and our sharply defined, much taller, Green Mountains to the east. The Green Mountains we see today are significantly worn down due to erosion.

On this quiet day in February, I am able to listen to the cracking ice on Lake George and Lake Champlain—the only masses separating Fort Ticonderoga from the Adirondacks and the Green Mountains. It is difficult to imagine that at one point, Lake George was two rivers; one flowing south into the present day Hudson River, and the second flowing north into the present day Lake Champlain. Lake George as we know it today was not formed until approximately 11,000 years ago, just 10,000 years after Lake Champlain, as a result of glacial retreat. Now, we can witness the outflow of Lake George drained into southern Lake Champlain via the La Chute.

Champlain Valley today

Today, Lake Champlain divides the old metamorphic rocks of the Adirondacks from the faulted sedimentary rocks of the Champlain Valley, which eventually give way to the younger (compared to the ADKs) metamorphic rocks of the Green Mountains.

Fort Ticonderoga has its own very unique history, as it relates to our own kind, but it is important to understand that this area is much more than that. All it takes is a quiet, wintry day to tune into momentous geological transformations that have sculpted the beautiful landscape we are able to observe today. And we are not the only ones taking advantage of these resources. Although sometimes hard to imagine in what seems like a desolate environment in the middle of winter; a few months from now, we will see an incredible amount of biological diversity coming out of the woodwork. Gulls, Bald Eagles, and osprey soar above the valley, overlooking ideal habitats for bobcats, coyotes, fishers and white-tailed deer.

As you prepare for another lively summer season at our site, do not forget to also take a good, far look around. There is a lot to see outside of these walls.

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