Glaciology 101

Hubbard Glacier in Seward, Alaska
Hubbard Glacier in Seward, Alaska

The first time you see a glacier, you’ll be rendered speechless. The undulating surfaces are a deep, resonant blue. The ice crackles, inching across the landscape like wide ribbon of slow, powerful destruction. And when you trace the glacier’s path with your eyes, you’ll realize: the ice carved this landscape like a sculptor with a spoon.

Named from the French word glace (meaning ice), glaciers are often called “rivers of ice.” They’re blue for the same reason that water is blue: the chemical bond between oxygen and hydrogen in water absorbs light in the red end of the visible light spectrum. And they’re disappearing: according to the most recent scientific estimates, glacial ice has decreased more than 70% since the beginning of the nineteenth century. If you want to visit these magical formations, you shouldn’t wait.

Types of Glaciers
While they’re all are made of frozen freshwater, there are lots of different kinds of glaciers. Broadly speaking, they fall into two categories: alpine glaciers and ice sheets.

Alpine glaciers include mountain glaciers (which develop in high mountainous regions, often flowing out of icefields that span several peaks or even an entire mountain range), valley glaciers (which originate from mountain glaciers, then spill down into valleys like giant tongues), piedmont glaciers (which occur when steep valley glaciers spill onto relatively flat plains and spread out into broader, flatter shapes), and hanging glaciers (which are formed when a valley glacier system retreats, leaving small glaciers in valleys above the shrunken central glacier surface.)

Ice sheets, on the other hand, occur when sheets of ice extend over the sea, floating on the saltwater. The best-known of these is the Antarctic ice sheet, which covers approximately 98% of the Antarctic continent and is the single largest mass of ice on Earth.

Mendenhall Glacier, Juneau, Alaska
Mendenhall Glacier in Juneau, Alaska

Where To See Glaciers
If you’re not planning a trip to Antarctica, your best bet for USA-based glacier view is in Alaska and the mountainous West.

In Alaska, explore Glacier Bay National Park (which covers 3.3 million acres) by boat or explore the Mendenhall Glacier (which is located only 15 minutes outside of Juneau) by foot. But go soon—the glacier is roughly 12 miles long, and it has receded 1.75 miles since 1958.

If you want to see big ice in the lower 48, check out Mount Rainier in Washington state. With 27 major glaciers, this national park also boasts two records: the Emmons Glacier has the largest area (4.3 square miles) and the Carbon Glacier has the lowest terminus altitude (3,600 feet) of all the glaciers in the contiguous 48 states.

Stuck inland? Head to Wyoming, the home of the largest glacier in the Rockies. Gannett Glacier in the Shoshone National Forest is between 800 and 900 acres, and is a year-round water source for the state’s many rivers and streams.

How To Stay Safe
There are two main ways to get hurt on a glacier: by falling into a crevasse and by sliding on glacial ice. To mitigate these risks, wear crampons if necessary to prevent sliding, and never assume that snow-covered glaciers are safe—after all, just because you can’t see the crevasses doesn’t mean they’re not there. Always make sure that you’ve either received proper instruction or are accompanied by an experienced guide.