Waccabuc Lake, Oscaleta Lake, and Lake Rippowam are all located in Westchester County, New York, and are each glacial lakes. You can see them all from this outlook. The infoboard at GZ can tell you a bit about where each of the lakes are.
What is a Glacial Lake?
A glacial lake is a body of water that forms in a depression or basin created by a glacier. These lakes are typically found in regions that were once covered by glaciers during past ice ages, though some can form in more recent times as glaciers retreat.
How Are Glacial Lakes Formed?
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Glacier Movement:
- Glaciers are massive rivers of ice that move slowly over land. As they advance, glaciers carve out the landscape through a process called erosion.
- The weight and movement of the glacier scrape and carve deep depressions into the earth's surface.
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Erosion and Depressions:
- The glacier's movement erodes the ground beneath it, creating basins or valleys.
- As glaciers move, they act like giant bulldozers, grinding and scooping up soil, rocks, and debris, leaving behind large, bowl-shaped depressions.
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Glacial Retreat:
- When a glacier begins to melt and retreat (typically due to warming temperatures), it leaves behind these depressions or basins.
- As the glacier melts, the depression often fills with meltwater, creating a lake. This can happen gradually as the glacier retreats or more suddenly if a large section of the glacier breaks apart.
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Types of Glacial Lakes:
- Kettle Lakes: These form when large chunks of ice become buried in sediment. When the ice melts, a depression is left behind, which can fill with water.
- Cirque Lakes: Formed in the basin at the head of a glacier, often in a cirque—a steep-walled bowl-shaped valley carved by the glacier.
- Tarn Lakes: A specific type of cirque lake, these are often smaller and occur at higher altitudes.
- Moraine-Dammed Lakes: Form when a glacier's movement creates a natural dam made of debris, and meltwater accumulates behind it, forming a lake.
Example:
Imagine a large glacier moving slowly over a valley. As it moves, the glacier grinds down the valley floor, deepening and widening it. Once the glacier melts, the depression it left behind fills with water, forming a glacial lake.
Why Are Glacial Lakes Important?
- Ecological Significance: These lakes often have unique ecosystems with specialized species adapted to cold, nutrient-poor conditions.
- Water Supply: Many glacial lakes serve as important freshwater sources for surrounding regions.
- Recreational Value: Glacial lakes are often beautiful, scenic spots for outdoor activities like boating, fishing, and hiking.
Waccabuc Lake
- Type: Kettle Lake
- Explanation: Waccabuc Lake is likely a kettle lake, which forms when large chunks of ice become buried in sediment during the retreat of a glacier. When the ice chunks melt, they leave behind a depression that fills with water. These lakes are common in areas once covered by continental glaciers, like the region around Waccabuc.
Oscaleta Lake
- Type: Kettle Lake
- Explanation: Oscaleta Lake also appears to be a kettle lake. The area surrounding Oscaleta, like much of Westchester County, is characterized by glacial activity. As with Waccabuc, this lake likely formed from depressions created by large ice blocks that were left behind as the glacier retreated.
Lake Rippowam
- Type: Moraine-Dammed Lake
- Explanation: Lake Rippowam is more likely to be a moraine-dammed lake. Moraine-dammed lakes form when a glacier pushes debris (such as rocks, dirt, and sand) to the edges of its path, creating a natural dam. As the glacier retreats, water that is trapped behind the moraine can form a lake. Given the size and location of Lake Rippowam, it’s possible that the lake was formed when a glacier left behind a terminal moraine, creating a barrier that allowed meltwater to collect.
No need to go down the cliffside. If it says you need to, it is not there!
Questions:
1. What are a few ways glacial lakes can form? What types of glacial lakes are there?
2. At GZ, what kinds of evidence can you see throughout the landscape that a glacier went through?
3. Take a photo of you or an object at GZ. (Optional)
Send me these answers.
Sources:
"Lake Information." Town of Lewisboro, Town of Lewisboro, www.lewisborogov.com/lakes/waccabuc-oscaleta-rippowam.
"Lake Characteristics and Recreational Use in Westchester County." Westchester County Parks, Westchester County Parks Department, www.westchestercountyparks.gov/lakes.
Parker, John, et al. Physical Geography: Earth and Its Environment. 12th ed., Pearson, 2021.
"Glacial Lakes." National Snow & Ice Data Center, University of Colorado Boulder, 10 Sept. 2020, https://nsidc.org/cryosphere/glaciers. Accessed 17 Nov. 2024.
Benn, Douglas I., and David J. A. Evans. Glaciers and Glaciation. 3rd ed., Routledge, 2010.