NASA: USA - The Icy Origins of the Finger Lakes - 12.11.13
Posted by Ricardo Marcenaro | Posted in NASA: USA - The Icy Origins of the Finger Lakes - 12.11.13 | Posted on 15:42
The Finger Lakes—a group of long,
roughly parallel lakes in upstate New York—got their name for obvious
reasons. On a map, the narrow lakes look similar to outstretched digits.
Seneca and Cayuga—the two largest Finger Lakes—are among the deepest
lakes in North America. Lake Cayuga descends about 435 feet (133 meters)
at its deepest point—putting it about 53 feet (16 meters) below sea
level.
On May 6, 2013, the Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra
satellite acquired this true-color image of the Finger Lakes. Water
appears dark blue. Farms and orchards, mainly around the northern part
of the lakes, are beige. Forested areas south of the lake are brown
because leaves had not fully emerged in early May. However, grass and
other low-lying vegetation in meadows had turned some parts of the
landscape green.
Millions of years ago, the lakes were northward-flowing streams that ran through a series of narrow valleys shaped like a V. Beginning about two million years ago, during a period known as the Pleistocene glaciation, sheets of ice crept south and buried those valleys under ice.
As the glaciers pushed south, they gouged the bottoms and sides of
the narrow valleys, deepening and widening them into vertical U shapes. This process, known as glacial scouring, likely happened multiple times as orbital variations in global climate—called Milankovitch cycles—produced cycles of advancing and retreating ice.
The most recent glacial advance occurred about 21,000 years ago, when
ice covered much of New York state and New England. The glaciers
advanced and retreated, melting for the last time about 10,000 years
ago. In the process, they left debris piles called recessional moraines
in the valleys. In many cases, these moraines functioned like dams,
blocking streams and causing the valleys to fill with water and become
lakes.
References
- Cornell University Finger Lakes: Graphics. Accessed October 8, 2013.
- Paleontological Research Institution Finger Lakes Geology. Accessed October 8, 2013.
Further Reading
- Mullins, H. & Eyles N. (1996) Subsurface geologic investigations of New York Finger Lakes: implications for late Quaternary deglaciation and environmental change. GSA Special Papers, (311).
- item two
NASA image courtesy of the LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Adam Voiland.
- Instrument:
- Terra - MODIS
NASA: USA - The Icy Origins of the Finger Lakes - 12.11.13
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