Geology from 30,000 Feet: Malaspina Glacier


Sometimes – not very often, certainly – the weather is clear along the coast of Alaska from Anchorage to Juneau. When it is clear, the scenery is spectacular. And perhaps the prize along the Gulf of Alaska coast is the mighty Malaspina Glacier, the largest piedmont glacier in the world and the largest glacier of any kind in North America.

Malaspina Glacier from 30,000 Feet

Malaspina Glacier from 30,000 Feet

A piedmont glacier is a glimpse into the last ice age. They form when valley glaciers spill out onto relatively flat plains, where they spread out into bulb-like lobes. Here, the Seward and Agassiz Glaciers, along with half a down other, smaller glaciers, flow out onto the coastal plain to create the Rhode Island-sized Malaspina Glacier. The Malaspina gives you a sense of what the northern third of North America was like during the Wisconsian Ice Age.

As WC has described before, glacial moraines form along the walls of valley glaciers. When two glaciers join, they create a moraine down the middle of the glacier, a medial moraine. But when moraines reach a piedmont glacier, other forces, ranging from elastic bending to ground friction to turbulent flow to create stunningly complex and – at least to a geology scholar – beautiful patters. In late summer, after the surface snow melts and the patterns are fully exposed, they are strikingly beautiful.

Seward Glacier Entering the Malaspina Glacier

Seward Glacier Entering the Malaspina Glacier

You can see the complex moraines banding the easterly side of the upper Malaspina. Portions of the Malaspina are more than 1,000 meters thick, extending more than 1,000 meters below sea level.

Complex Moraine Banding and Folding Along the Southeasterly Side

Complex Moraine Banding and Folding Along the Southeasterly Side

Glaciers transport absolutely astonishing amounts of rock, sand and mud. There are two mechanisms: water transport, via sub-surface streams that have the characteristic glacial flour, scoured by the ice from the bedrock, and by the slower movement of the ice itself. As you near the snout of most glaciers, the ratio of ice to rock and gravel decreases. The ice, after all, melts and the gravel remains. Eventually, at the 65-mile long snout of Malaspina, you get extensive hills of moraine underlain with ice that hasn’t melted yet.

Complex Moraines at Junction of Agassiz and Seward Glaciers, Below the Smovar Hills

Complex Moraines at Junction of Agassiz and Seward Glaciers, Below the Smovar Hills

Where major glaciers merge, as the Agassiz and Seward do, you can get very large linear moraines, And those striking pattens in the central part of the lobe, as different parts of the ice move at different speeds. The photos don’t beginning to capture the sheer size of the thing. And the blue tints induce by the plexiglas windows of the Alaska Airlines 737 distort the colors, but it does give you a sense of the scale of the Malaspina.

It was a treat to get to see and photograph it. WC’s thanks to the flight attendant who took WC’s camera up to the flight deck to capture the last image.

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One thought on “Geology from 30,000 Feet: Malaspina Glacier

  1. Lovely photos, WC! I had the very great fortune of seeing the Malaspina on a similarly fine day in my high school years. I looked down on the intricate moraines and the amazing size of the glacier and thought, “I want to know what’s happening there.” My love affair with geology started at that moment, even though I didn’t know what to call it at the time. What a beautiful trip down memory lane. Thanks!

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