I feel like an idiot. I have long been familiar with the term “glacial speed” used to refer to something that’s moving or happening very slowly. But until I saw a glacier up close and started learning about these formations, I never realized that all glaciers are continually on the move. Glacial speed actually refers to the speed of glaciers. Several writers have referred to them as “shape-shifting rivers of ice.”
The movement of glaciers has upset people for a variety of reasons over time—so much so that at one point clergy tried to exorcise demons out of them. Whether growing, shrinking, or retaining their size, glaciers are continually going somewhere.
The Lifecycle of a Glacier
In simplified terms, a glacier is a formation made up of ice, snow, rock, debris, and water. Glaciers form when snow accumulates over decades with so much size and weight that the snow compresses and turns to a very dense form of ice. Glacial ice looks blue rather than white or clear because it is so dense that the air trapped inside is compressed and unable to reflect light. The dense ice essentially absorbs all colors in the spectrum except blue. In fact, glacial ice is technically a rock that is mono-mineralic—made of one mineral, crystalline water.
Glaciers grow by accumulating snow and shrink due to melting, evaporation, and calving. (When a chunk breaks off a glacier and drops to form an iceberg or other formation, that’s known as calving and it’s something tourists crowd the decks of cruise ships in the hopes of seeing—and hearing—while in Alaska.)
What Makes Glaciers Move
There are two forces that cause glaciers to move. Ice deformation is one of these forces, and it occurs on a microscopic scale as individual ice crystals reposition themselves. The crystals often slide past one another, crack, and recrystallize. The glacier is effectively collapsing in on itself and that movement propels it downward and outward.
The second force that causes glaciers to move is sliding at the base as water causes the ice to glide over bedrock or sediment. Water accumulates at the base of a glacier from a variety of causes such as:
- Heat produced by radioactive decay or stored in the earth causing ice to melt
- Melting water on the surface of the glacier dripping through crevasses in the ice down to the bottom
- Friction caused by movement at the base causing ice to melt
All the combined movement forces are known as glacial flow.
To see glaciers move, you need to take timelapse photos. Most glaciers move a little less than 10 inches per day and some are much slower than that. However, other glaciers can move nearly 100 feet per day.
Attack of the Killer Glaciers
In the 1600s, during what historians often refer to as the Little Ice Age, glaciers in the French Alps were advancing at a pace that sent people into a panic. Officials insisted that some glaciers were moving at the rate of “over a musket shot every day.” Villages and farms were overrun by the rivers of ice.
Desperate people begged the Bishop of Geneva for assistance, and he came to the town of Chamonix and performed an exorcism on the glacier, casting out the icy demons that threatened farms and livestock. The rites appeared to work and glacier began to recede.
And then it came back, and so did the bishop. The holy war against the ice continued for decades there and in other towns throughout the Alps.
Entering the Desolation Zone
In areas where glaciers are receding rather than advancing, the ground released from the compressed ice and sediment is sometimes referred to as the “desolation zone” The earth in these areas has been without organic materials for so many years that it takes a long time for plant life to return. It looks like the surface of the moon (so long as you don’t look up and notice the glacier and atmospheric sky in the background.)
Speckled rocks that have tumbled through centuries of glacial movement lay scattered like eggs on the soft, barren soil. In rare pockets where organic plant matter was trapped within the glacier, it provides fuel for small areas of more rapid regrowth. When we kayaked across Mendhenhall Lake to view the Mendenhall Glacier up close, we were able to walk the shifting sand and feel privileged to witness this unique part of the life cycle.
Movement Does Not Equal Growth
Since glaciers are constantly moving, their mobility is not necessarily an indication of whether they are growing or shrinking. Glaciers in many parts of the world are losing mass, but some, such as the Jakobshavn Glacier in Greenland have generally been adding overall mass. Glaciers require cold temperatures to retain mass or gross, so warming trends in many parts of the world are causing glaciers to shrink.
Where people once feared that advancing glaciers would swallow up their world in ice, many people now fear that melting glaciers will drown the world. A lot of those people also believe that the process will slow down if we all drive electric cars, but I believe we’d all have to stop driving anything and revert to a very static, simple, non-consumer lifestyle to have much hope of making a difference in climate patterns. Carbon offsets aren’t going to trick a glacier into staying cold no matter how many you buy.
Glaciers, like all aspects of the world around us, are changing and will continue to change. Take a few moments each day to observe what’s around you even when you’re not on vacation. Marvel at the beauty God created. We are not guaranteed that it will be there tomorrow.
Information in this article came from a variety of sources, including unpublished notes that I wish I’d set down in greater detail. Online accounts include:
- National Park Service (https://www.nps.gov/articles/howglaciersmove.htm)
- U.S. Geological Survey (https://www.usgs.gov/faqs/why-glacier-ice-blue#:~:text=Glacier%20ice%20is%20blue%20because,the%20more%20blue%20it%20appears.)
- National Snow and Ice Data Center (https://nsidc.org/learn/parts-cryosphere/glaciers/science-glaciers#:~:text=As%20the%20snow%20slowly%20accumulates,the%20melting%20and%20evaporation%20occur.)
- The Times (https://www.thetimes.com/article/weather-eye-spiritual-protection-from-advancing-glaciers-zw9mnprrs25)
- The Smithsonian (https://ocean.si.edu/ecosystems/poles/close-and-personal-fastest-glacier-world#:~:text=To%20really%20see%20a%20glacier,unseen%20to%20the%20human%20eye.)
Many of my books are set during the last century of the Little Ice Age. But while characters in Restitution and A Certain Want of Reason have to deal with some snow, none of them are threatened by killer glaciers. Maybe I need to set my next story in the Alps…