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Polar Mail

December 11, 2007

On Day 15, the Polar Discovery team posed this question to our readers:

Our flight took us over the McMurdo Ice Shelf, where we saw these intricate patterns engraved into the surface of the glacier. I’m not sure what makes all the colors or why they appear in such fanciful shapes. The blue is probably meltwater pooling above clean ice, and the dark may be dust that blew in on the wind and for some reason didn’t wash away. It wasn’t an isolated occurrence, either; we flew over pitted surfaces like this continuously for miles. If any readers know why these shapes develop, please e-mail us at!

Here is one of our answers so far:

The shapes are likely caused by melting of the surface due to the wind-blown dust from Black Island. The dark material causes the surface melting during the austral summer months. If you are camping at Mt Discovery that would be the route the helo would take from McMurdo. The area you flew over is called the “Dirty Ice”.

Have been reading your journal regularly and find it very enjoyable. Hope the weather stays good for a while.

Dave Bresnahan

Answer from the Chief Scientist of the expedition
Dear Dave,

Thanks for responding, and we are glad you are reading the Polar Discovery website. It doesn't seem that long ago that you were station manager at McMurdo, so this is all familiar territory for you! The dirty ice Chris photographed is probably produced by ice flow around Brown Peninsula, which incorporates loose debris into the ice, in addition to the surface melting and wind-blown dust.

 Best regards, Mark Kurz