Recently on a walk at Dungeness Spit on the Olympic Peninsula, my wife and I saw a curious phenomenon. If you haven’t been out to this five-mile finger of sand and driftwood, you are missing out. It’s pretty darned amazing. That being written, we didn’t actually walk the spit. Unlike we usually did at the beach, we turned left, instead of right, and walked along the bluff that rises out of the water and runs toward Port Angeles. I have long liked this spot. The bluff is geology in motion. As waves undercut the face, sand and cobbles and boulders constantly cascade to the sea in a steady state of status change from bluff to beach.
But that’s not what intrigued us this time. Instead, we were excited by the ice. It occurred only in a short stretch of bluff, perhaps 100 yards in extent, about a mile into our walk. I noticed it from up the beach, attracted by the white blotches in a landscape of gray and khaki. Although we had seen ice and snow on the ground atop the bluff, I didn’t think the white was ice at first; it seemed too incongruous, here at the beach. Not until I touched the ice was I really sure.
What was the ice doing here and why only here? The main feature we noticed that was different was the layer of gray sediment in the bluff. We hadn’t seen it before. Unlike the previous sections we had passed, which consisted of beds of sand and conglomerates, the gray was very fine grained, basically clay. (If it had been warmer, I could easily imagine a nice, mud facial, but I digress.) Packed tightly together, the clay particles had prevented water penetration into the bed. This had forced water that had percolated down through the overlying sand layers to flow out to the surface, in this case, the bluff face. Here, the water had encountered the freezing temperatures that had caused the snow and ice atop the bluff. The result was the ice that had attracted our attention.
At the bottom of the bluff, the water had spread out and frozen into small alluvial fans. Where it encountered boulders, it created small islands of rock surrounded by a sheet of ice. When I walked up to the base of the bluff, I realized that what I had thought was mud was actually mud-covered ice with water flowing underneath. The mud was insulating the ice at the surface and preventing it from melting. Underneath, the temperature had warmed enough so that water flowed instead of froze. At least that’s my speculation. I am open to other suggestions. Even if I am wrong, my wife and I still had fun trying to figure out what we saw.
A few days before this exciting moment, I had seen another cryogenic scene of wonder. I was walking on the Centennial Trail, north of Arlington, with my pal Scott. I had stepped off the pavement onto a dirt path paralleling the trail. At my feet, it looked like the earth was eating itself, or at least sucking pebbles back into its innards.
This was an optical illusion. What I was seeing was frost heaving. As the name implies, freezing water was expanding and moving the ground. Because it’s easier to push up against the minimally resistant atmosphere versus down against the entire planet, the ice heaved up. The pebble, however, appears to be sinking because the surrounding soil gets heaved up more, and more easily, than the pebble. The pebble was moving but ever so slightly. During each freeze, the pebble rose a wee tad; during the thaw, perhaps some sediment filled the nascent open space under the pebble, causing it to rise.
Out here in the Puget lowlands, we tend not to have serious freeze/thaw cycles, so this feature of the cryosphere occurs relatively infrequently. In contrast, on the east coast, frost heaving is common, and was more so back in the 1700s and 1800s at the end of the Little Ice Age. The result was the regular upchucking of boulders and cobbles in fields, which farmers called New England potatoes. In his splendid book Stone by Stone, Robert Thorson adds that some people thought “the stones grew from Satan’s seeds.” Despite the supposed connection to the prince of darkness, people used the stones to build the extensive stone walls that graced the east.
Two weeks after my walk with Scott, we were again riding on the trail. Winter was beginning to close down. The day was warm and sunny. Buds were starting to appear on branches. Birds were singing of their virtues. Crocuses were smiling in purple and orange. Spring was in the air. I’ll miss the ice and the stories it creates.
Word of the week - Cryogenic basically refers to freezing. The cryosphere is the realm where water exists as ice, such as glaciers, hair ice, needle ice, and frost heaving. Cryo comes from ancient Greek κρύος frost, icy cold.
Upcoming Events:
March 10 - 7PM - Treehouse Cafe - I will be the speaker, talking about Puget Sound, for the Bainbridge Island Open Mic Science Series. It’s free and open to all. Sorry there isn’t a live link but it will be fun.
March 29 - Arundel Books - 1PM - I will be leading another walk from the updated edition of Seattle Walks. We’ll be exploring the historic waterfront.
April 16 - Burke Museum - 6pm - I am excited to announce the book launch for Wild in Seattle: Stories at the Crossroads of People and Nature. More info to come.
April 26 – Edmonds Bookshop – 11:00 A.M. – I will be stopping by the store during Indie Bookstore Day. I will be wearing my new book-themed vest as part of a sartorial contest! More info to come.
April 28 - Elliott Bay Books - 7pm - I will be in conversation with the wonderful Claudia Castro Luna. We’ll be talking about Wild in Seattle: Stories at the Crossroads of People and Nature.
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