Kettle Near Gígjökull Glacier, Iceland

September 17, 2015

 

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Photographer: Thomas McGuire
Summary Author: Thomas McGuire

In 1837, Swiss-born naturalist Louis Agassiz was the first to publish evidence that Earth had been subject to at least one major ice age in the prehistoric past. A number of naturalists in Europe found features left by alpine mountain glaciers, but in the lowlands of northern Europe where glaciers had never been observed. It was subsequently revealed that large parts of North America and Europe were repeatedly covered by massive ice sheets similar to icecaps of Greenland and Antarctica.

KettlesIcelanduntitledAmong the landforms cited as evidence of these ice caps are kettles, bowl-shaped features formed when blocks of ice melt to create depressions in the land. The top photo shows a small kettle at the Gígjökull Glacier, Iceland. Green photosynthetic algae have quickly invaded the nutrient rich water in the kettle.

Kettles are particularly common where receding ice sheets pushed and carried sediment forward, even as the ice front melted back. Some kettles are dry (photo at left) and some contain water but are closed depressions with no outlet to a nearby stream. Walking across the sediment in these kettles my feet often sunk into the surface where very recent ice had melted.

Photo Details: Top - Camera Maker: OLYMPUS IMAGING CORP; Camera Model: E-510; Focal Length: 14.0mm; Aperture: ƒ/6.3; Exposure Time: 0.0080 s (1/125); ISO equiv: 100 ; Software: Adobe Photoshop Elements 9.0 Macintosh.