To a geologist, glaciers are among the most exciting features on Earth. Though they seem to creep along at impossibly slow speeds, in geologic time glaciers are relatively fast, powerful landscape artists that can carve out valleys and fjords in just a few thousand years.
Glaciers also provide an environmental record by trapping air bubbles in ice that reveal atmospheric conditions in the past. And because they are very sensitive to climate, growing and advancing when it’s cold and shrinking and retreating when its warm, they can be used as proxies for regional temperatures.
Over geologic time, they have ebbed and flowed with natural climate cycles. Today, the world’s glaciers are in retreat, sped up by relatively rapid warming of the globe. In our own Glacier National Park in Montana, only 26 named glaciers remain out of the 150 known in 1850. They are predicted to be completely gone by 2030 if current warming continues at the same rate.
Here we have collected 13 stunning images of some of the world’s most impressive and beautiful glaciers, captured from space by astronauts and satellites.
Above: Bear Glacier, Alaska
This image taken in 2005 of Bear Glacier highlights the beautiful color of many glacial lakes. The hue is caused by the silt that is finely ground away from the valley walls by the glacier and deposited in the lake. The particles in this “glacial flour” can be very reflective, turning the water into a distinctive greenish blue. The lake, eight miles up from the terminus of the glacier, was held in place by the glacier, but in 2008 it broke through and drained into Resurrection Bay in Kenai Fjords National Park.
The grey stripe down the middle of the glacier is called a medial moraine. It is formed when two glaciers flow into each other and join on their way downhill. When glaciers come together, their lateral moraines, long ridges formed along their edges as the freeze-thaw cycle of the glacier breaks off chunks of rock from the surrounding walls, meet to form a rocky ridge along the center of the joined glaciers.
Image: GeoEye/NASA, 2005.
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