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What are the Finger Lakes?

Millions of years ago the northern portion of the Finger Lakes region was a tropical, salt water sea. Over time, mud, sand, vegetation, and dead shelled creatures became deposits of shales, limestone, sandstone, and dolomite. If you look closely at the exposed sedimentary layers of the region you can often find fossils of trilobites, bryozoas, corals, crinoids, brachiopods, and mullosks. (One of the best places to find these fossils is at Portland Point on the east side of Cayuga Lake near Lansing where more than a hundred species can be found in shale along the roadside.)

When the sea receded, 24 parallel north-south river valleys were created. Later dinosaurs roamed this region, but they too died out. More recently, about a million years ago, a great freeze came down from the north. Enormous glaciers thought to have been a mile or more thick covered the region. Then they receded. This happened several times. Each time the glaciers proceeded southward, they scoured the land. When the last glaciers melted about 12,000-10,000 years ago, they left behind eleven finger-shaped basins that were filled with water from the melted glaciers. The Seneca Lake basin is scoured so deep, it is now 174 ft./53 m. below sea level. (Death Valley is 282 ft./85.9 m. below sea level.)

The streams that flowed through the gentle valleys during the days of the dinosaurs began carving these streams deeper and deeper, creating gorges. These gorges are home to nearly 900 waterfalls.

The glaciers left some other interesting physical features as well. Running east and west between Syracuse and Rochester and north and south between Lake Ontario and the Finger Lakes one can find what some consider to be one of best drumlin fields in the world. Shaped like an overturned spoons, these low rounded hills of glacial drift give an odd lumpiness to the land. There are more than 10,000 drumlins over the 100-mi./161-km. area. Hill Cumorah on Rt. 21 in the Town of Manchester in Ontario County and the eroded bluffs at Chimney Bluff State Park on Lake Ontario east of Sodus Bay in Wayne County are excellent examples of these drumlins.

In other places, south of Syracuse at Lime Hollow Center for Environment & Culture in Cortland, for example, one finds kames--conical hills of sand and gravel--along with kettles--circular depressions in the glacial deposits created by large pieces of ice left to melt in one spot. At Lime Hollow, these kettles are filled with turquoise-colored water. Kames, kettles and eskers--long, low, sinuous ridges of glacial rubble--can also be seen at Mendon Ponds Park in Mendon. This is Monroe County's largest park. In 1967 it was designated a National Natural Landmark by the National Park Service for its geological uniqueness, especially for the Devil's Bathtub, one of eleven known meromictic lakes in the country. A type of large kettle, the ridges that surround the water are so high that wind is prevented from moving across the surface of the water. Consequently, the water in the lake never circulates or "turns over" and there is a mirror effect to its motionless surface.

It should be noted that all the Finger Lakes run north to drain into Lake Ontario. However, just south of Ithaca (Tompkins County) in the small town of Danby, a rather insignificant-looking pond called Jennings Pond sits on a geological plateau of glacial moraine. The northern end of the pond drains toward the north (eventually) into Cayuga Lake while the southern end of the pond drains to the south into the Susquehanna River Basin. All waters south of this plateau drain into the Susquehanna River Basin.

From east to west, the 11 Finger Lakes are Otisco, Skaneateles, Owasco, Cayuga, Seneca, Keuka, Canandaigua, Honeoye, Canadice, Hemlock, and Conesus.

REFERENCE

Roadside Geology of New York by Bradford B. Van Diver. Mountain Press Publishing Co., Missoula, Mt., 1985. Considered a classic and still in print, this book discusses the geology of New York by route, allowing the reader to use the book as a geological guide while traveling that route.

For a detailed overview of the plant communities in the Finger Lakes, see: Guide to the Plant Communities of the Central Finger Lakes Region

Updated 16 October 2008