Not by Fire but by Ice


Discover What Killed the Dinosaurs . . . and Why it Could Soon Kill Us


26 Jun 07


Mount St. Helens’ Crater Glacier 
Advancing Three Feet Per Day

22 Jun 07 - Ever since St. Helens rumbled back to life in 2004, geologists have curiously watched the dichotomy of fire and ice play out.

Crater Glacier is like no other glacier in the world. It’s the only glacier with lava extruding through it and forming a dome. And while most glaciers are receding (I don’t agree - most glaciers are not receding), Crater Glacier is advancing three feet per day and forming a collar around the growing dome.

Crater Glacier started forming shortly after St. Helens blew its top on May 18, 1980. The glacier is fed by snow and falling rock and ice from the crater rim. The glacier is about 40 percent rock and 60 percent ice, USGS geologist Willie Scott said.

Originally, the glacier filled the void between the crater walls and the lava dome that formed from 1980 to 1986.

When the 2004 eruption pushed a new dome up through the ice, geologists feared the 1,300-degree lava would melt the glacier, causing a lahar to spew from the open end of the horseshoe-shape crater.

What happened next surprised the scientists.

Cooling rock on the outside of the dome insulated the glacier from the lava, and only about 10 percent of the glacier melted, said Carolyn Driedger, a USGS hydrologist. Instead, the dome, growing by a pickup truckload of lava every two seconds, split the glacier into two moraines – deposits of glacial rock and soil – pressing each against the crater walls. The pinching forced the glacier arms to double in depth and increase their speed.

See entire article by Craig Hill of The News Tribune
Thanks to Clay Olson for this link

Note: "By mid-2008, the glacier completely encircled the lava domes.
In addition, new glaciers (rock or ice) have formed around Crater Glacier as well."


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