Glacial Thoughts…

On the Triple Crown Glacier at 5,700’ elevation in the Alaska Range.   In case you are interested, that is a De Havilland Otter plane behind us.   It is the workhorse of the Alaskan bush country.

Getting ready with our snow gaiters on.  The excitement is building.

Onboard and aloft as we head towards Denali and her glaciers.   If only the cloud cover would behave, and it won’t.   

We don’t get to see Denali.   There is a cloud ceiling at about 6,000’, so we don’t get to see any of the higher peaks.

Looking down on one of the many many glacier melt rivers that riddle this old glacier bed valley.

What makes glaciers?   More snow year over year in excess of the snow/ice that melts and then do that over thousands of years.   Though with over 100’ of snow a year, in cold years a glacier can grow quite rapidly as little of it melts.

As the glacier builds it gets thicker and heavier, it squeezes the lower ice into ever more dense forms.  With the weight of all that ice combined with the slope of the ground the glacier moves downward.   The downward movement generates friction which causes the ice on the bottom of the glacier to melt.  As it slides the glacier picks up rocks making a highly abrasive slurry that grinds the valley floor essentially bulldozing these “U” shaped valleys.

This is what a lower elevation glacier looks like at the Ruth Glacier.   The frozen ice is actually under the dirt, aka moraine.   It is amazing to me how much earth is on top of the glacier.

As the glaciers slide around corners the glacier fractures/cracks forming crevasses.   Some of those crevasses go from the top all the way to the bottom and scoop the rocks and dirt as the glacier moves, lifting the rocks to the top of the glacier.

The sides of the glaciers scrape along the valley walls creating lines of rocks parallel with the glacier’s flow.   Those lines are called lateral moraines.   Sometimes lateral moraines can occur in the middle of a glaciers as the glacier splits around a particularly hard rock formation or where two glaciers join together.

In the above photo, there is a river of glacial meltwater flowing out from one glacier that has receded and under the lower area of the Ruth Glacier.

The terminus of a hanging glacier.

The massive Kalitna Glacier.

Notice the snow in all the crevasses creating a quilted patchwork of ice and snow.

A hanging glacier with a small river running beside it down the cliff face.   We are probably 3 miles away from it.   There is no sense of scale up here.   If it weren’t for the pilot’s radar, we would have no idea as everything is immense and without reference.

  

Lateral moraines on the middle part of the Ruth Glacier.  Those moraines are over 500’ high.   They would look like a line of tall hills from ground level.

The Ruth Glacier, above, is 2+ miles wide, over 3,000’ deep, and 25 miles long.

The Kaklitna Glacier, above, as seen from the Triple Crown Glacier, is 4+ miles wide, over 4,000’ deep, and 46 miles long.   That is a lot of creeping ice.   4,000’ deep; that would put the bottom of the glacier well below sea level.

The crevasses fill with meltwater and shine this iridescent blue.   It looks very inviting, but at 32 degrees, count me out!

The glacier surface ice resembles semi-frozen slush like I used to play in as a kid in Kansas.   As we walk around, our boots sink in about. 8” or so with that classic snow crunch sound.

Karen in her element.

The view looking south from our landing spot on the Triple Crown Glacier.

One of the many hanging glaciers.

Now in these views, we are flying back to Talkeetna.  Big “U” shaped valleys result from glacial carving.  “V” shaped valleys are from water erosion.   We sometimes see big “U” valleys with “V” valleys in the bottoms.   More typically, the “V” valleys will intersect the “U” valleys.

River of glacier meltwater carrying the glacial flour (molecular-level fine silt).   The sediments are very rich in nutrients and because they are at the near molecular level in size they are bioavailable.   Notice the lush vegetation growing along the banks.

And now for a selection of videos.

 Flying up the Ruth Glacier.

 Lateral moraines near the middle of the Ruth Glacier.

 Crevasses on the Ruth Glacier.

 Giant crevasses on the Kalitna Glacier.   Some of these crevasses are 4,000’ deep.

 Landing on the Triple Crown Glacier.

 Panorama from the Triple Crown Glacier.

 Sharp pointy mountain peaks near Denali.

 Seracs on an unnamed glacier.  The big seracs may be larger than a city block and taller than a skyscraper building.

 Glacier flyby.   BTW, we are over a 1/4 mile away from the rocks even though it looks like we are much closer.

 White glaciers and black rocks.