Picture of the Day: The Dirty Tracks of Alaska's Susitna Glacier

More

537509main_susitna_ast_2009239_lrg_full.jpg

Glaciers, like rivers, flow downhill, gathering dust and dirt along the way -- and leaving a trail. This image, a composite of several infrared snapshots captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite on August 27, 2009, shows the long, slow journey of Alaska's Susitna Glacier.

"Vegetation is red and the glacier's surface is marbled with dirt-free blue ice and dirt-coated brown ice," NASA explained. "Infusions of relatively clean ice push in from tributaries in the north. The glacier surface appears especially complex near the center of the image, where a tributary has pushed the ice in the main glacier slightly southward."

Geologists once believed that some of the slopes and steep cliffs seen on the glacier's surface were caused by a 7.9-magnitude earthquake that shook the region in November 2002. It seems, though, that they were in fact caused by surges, or quick bursts of movement, in tributary glaciers. "Glacier surges -- typically short-lived events where a glacier moves many times its normal rate -- can occur when melt water accumulates at the base and lubricates the flow," according to NASA. "This water may be supplied by meltwater lakes that accumulate on top of the glacier; some are visible in the lower left corner of this image. The underlying bedrock can also contribute to glacier surges, with soft, easily deformed rock leading to more frequent surges."

View more Pictures of the Day.

Image: NASA.

Jump to comments
Presented by

Nicholas Jackson is a former associate editor at The Atlantic.

Get Today's Top Stories in Your Inbox (preview)

The Time JFK Called the Air Force to Complain About a 'Silly Bastard'

51 years ago, President John F. Kennedy made a very angry phone call.


Elsewhere on the web

Join the Discussion

After you comment, click Post. If you’re not already logged in you will be asked to log in or register. blog comments powered by Disqus

Video

Adventures in Legal Weed

Colorado is now well into its first year as the first state to legalize recreational marijuana. How's it going? James Hamblin visits Aspen.

Video

What Makes a Story Great?

The storytellers behind House of CardsandThis American Life reflect on the creative process.

Video

Tracing Sriracha's Origin to Thailand

Ever wonder how the wildly popular hot sauce got its name? It all started in Si Racha.

Video

Where Confiscated Wildlife Ends Up

A government facility outside of Denver houses more than a million products of the illegal wildlife trade, from tigers and bears to bald eagles.

Video

Is Wine Healthy?

James Hamblin prepares to impress his date with knowledge about the health benefits of wine.

Video

The World's Largest Balloon Festival

Nine days, more than 700 balloons, and a whole lot of hot air

Writers

Up
Down

More in Technology

Just In