Tuesday, December 29, 2015

North Cascades Glaciers: Notes from 1990

My graduate thesis field area involved an hypothesized fault and metamorphic gradients. But it was hard not to make note of glaciers in my field area.  

 Inspiration Glacier with Tepeh Towers and Klwatti Peak

Crossing the variety of glaciers in a safe manner took some planning and route consideration. Ice falls below the hanging glaciers were a significant hazard. One noteworthy observation was that lots of bare rock was exposed from areas where there had been glacial retreat.

Eldorado Glacier with moraine in foreground

The bare rock provided for excellent exposures of structures and contact relations as good as any road cut or mine wall.

Easy scramble and great bedrock exposures

At the time of my ventures in this area of the North Cascades in 1989 and 1990 the status of glaciers in the North Cascades was a bit sketchy as was my background on the glaciers. The South Cascade Glacier was the only glacier with mass balance data with other inventories reliant on historic aerial images. The overall pictures was that most of the glaciers had undergone substantial retreat post little ice age maximums. There was some sense that maybe the retreats had slowed. 

While I was not doing any glacial studies other than adding some very minimal mapping of moraines, my sense of glaciers in my field area in 1989 and 1990 was that most were retreating. This was mostly due to seeing large tracts of old ice that was wasting away along the margins of many of the glaciers.    

Wasting layers of glacial ice - note Mike on lower right of ice for scale.

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