Glaciers are the environment’s equivalent of an eraser, their massive size and steamroller capabilities can carve bedrock with micro-movement ease and their fluvial behaviors can transport/deposit sediment far and wide (even boulders the size of a VW bus).

After moving to the Seattle Area from my home town of Portland nearly three years ago the geologist in me was excited and equally concerned to learn that Puget Sound, ~12,500 years ago, was once buried beneath thousands of feet of the Cordilleran Ice Sheet. Contrary to other environmental scientists, my mind is less interested in the possibility of global warming and is instead fascinated with where nature’s next glacial period will take the earth and all of its new found inhabitants.

So knowing I was in ex-glacier territory, I decided to seize the chance to take a hike to help me work through these environmental ponderings. Given the awareness I gained from my undergraduate studies in climate change I knew interglacial periods like the one we are currently experiencing (which began well over 13,000 yrs ago) tend to last ~10,000 yrs, it took little effort for this scientific mind to begin to question ‘are temperatures increasing such a BAD thing?’ Obviously we as humans know we can’t undo what’s already been done by our activity upon the earth, but when it comes to the upcoming glacial period the jury in my mind is still out on whether or not we had an overall negative impact. Are global warming and the next glacial period temperature decreases in sync and ultimately, if they are, what does THAT mean?

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©Michael Cline

Don’t think for a second I am condoning additional pollution of the earth, but my tectonic courses enlightened me to the fact that volcanic eruptions have been decreasing as the core of the planet cools, therefore ironically the earth itself has decreased its own emissions. Granted I’ve yet to see an adequate mass balance study done on how many years of factory and/or vehicle emissions just one volcanic eruption contains or any reports conclusively showing what part those particles play in whether or not the next glacial period will arrive sooner vs. later because of their presence in the atmosphere (regardless of how/when they got there). Maybe we have expelled more than what nature has ever done historically or added chemicals that were never present in the past. Does that mean today’s potential state of global warming could successfully delay/impact the next glacial advance? This geologist seriously doubts it. So naturally I can’t help but ask… since past periods of heavy volcanic activity didn’t break the glacial cycle of ~10,000 years, how can we as humans do it with our modernization?  And am additionally left wondering… if the next glacial period IS coming, will it be in my lifetime and what would it be like?  Should you share the curiosity, here are some of my favorite representations of how glacial cover historically appeared locally and may look like again in the future.

With the Granite Mountain hike less than a one-hour drive from downtown Seattle making promises of 360 degree views on a clear day, I found my perfect opportunity to visually bring these ponderings to life. I wasn’t the least bit deterred by terms like ‘butt buster’ and ‘avalanche gully’. Instead the word ‘granite’ piqued my curiosity with the question “isn’t granite bedrock?” soon to follow. Bedrock is known to be beneath the ground and when perched atop a summit it’s always a geologist’s treat, so I attacked online mapping applications which had me visually flying along the I-90 corridor at a gliding eagle’s pace taking in a birds-eye view of Granite Mountain and the surrounding topography. The image search for the Cordilleran Ice Sheet revealed the fact that a glacial lobe once extended down the very valley before my eyes and I was hooked! That’s the hike for me! The lobe ~12,500 yrs ago (the geological timescale equivalent of ‘yesterday’) would’ve been similar to those portrayed in the image of the Purcell Lobe of the Cordilleran Ice Sheet that artist Rick Lovel rendered. His image has the viewer looking south-southeast from over present day Lake Pend Oreille and Sandpoint, Idaho. Additionally, the past glacial lobe that glided over present day North Bend would in some ways resembled this photo of the Lillooet Glacier in Canada.  The lobe may or may not have reached as far east as Granite Mountain, but the erosional ability of the melt-water alone could have easily chiseled Granite Mountain out of the bedrock.

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©Michael Cline

Granite Mountain

On the date of my exploration, at about 3000 feet elevation, the trail broke free of the tree line and the geologist in me easily found many opportunities to visualize the terrain as it would’ve appeared when glaciers filled the valleys. All it took was one glance down to my car, parked off of I-90 to gain a new respect for how much sediment/bedrock needed to be removed to create the valley I just climbed out of. Luckily for the remainder of the hike, views of surrounding peaks fed thoughts about how they were potentially part of what millions of years ago may have been ground surface and  kept me distracted me from the intensity of climbing miles of granite boulder steps (or more precisely give me justifiable reasons to pause and take a breather).

Since I was in no hurry I decided to take advantage of the beautifully exposed south-southwest facing rockscape and selected the perfect granite boulder recliner for a picnic lunch and megabytes of my memory card to be consumed. The up-close views of the a crescent shaped peak to the south-southeast that has Annette and Mirror Lakes tucked behind it and Mount Rainier effortlessly dwarfing those bedrock peaks only a geological stone’s throw away to the  south-southwest peacefully kept me company. Then after being re-energized by the food and the views, a gentle jaunt across the granite-walled gully (summer route) revealed views of Tuscohatchie Lake, Wright Mountain, and Kaleetan Peak dramatically filling the sky to the north-northeast. At the top, unfortunately the fire lookout was unstaffed, so after a final scramble up the cleaving white and black speckled granite ridge a panoramic view of it all was unveiled and it was suddenly worth the effort to get there.

Then what should happen? Within moments of taking in the glaciers that cover the sides of that ever-growing nearby Mount Rainier I became all the more impressed by its size, especially considering the counteractive forces those glaciers provide. Well you probably already guessed it, shortly thereafter the wonderings of where climate change will lead that mountain’s development began. And that will have to be wait for another article.

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©Jen Baptist
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