Mount Rainier and the Osceola Lahar

Mount Rainier rises above Washington’s skyline, looking down on Puget Sound like an empress overseeing her kingdom. “The Mountain is Out” is a common phrase in Seattle. This happens when clouds are absent or high enough to make the volcano’s peak visible. When I jump on I5 to head south, one of the first things I do is check on Mt. Rainier. How often have I said that phrase, even with no one in my car?

In July, a friend and I headed to Sunrise to experience the mountain up close. At least one trip a year to the park seems essential for my well-being. There is something special about hiking in the gaze of this mountain. She lifts one’s soul. Soon after we arrived, we acknowledged how our happiness soared in these wildlands and wondered why we didn’t come more often. 

Sourdough Ridge

Snow had mostly melted along Sourdough Ridge, and already, the wildflowers were popping. Pentstemons, paintbrushes, phlox, and daisies had all opened. A fly that mimics a bee landed on an alpine aster. These flies are essential pollinators in the subalpine ecosystem. A marmot grazed in a meadow, stuffing itself with the season’s new lush growth. The volcano rose in the cloudless sky to our west.

Mt Rainier is young in geologic terms, only about 500,000 years old. These stratovolcanoes happen where magma rises to the surface because of continental drift. The Juan de Fuca Tectonic Plate is gradually subducting under the North American Plate. This volcano is the most recent of a long series of volcanos in this section of the Cascades. Apparently, they have come and gone over the last 37 million years. According to geologists, these volcanos live for about a million years, at which point, if subduction is still occurring in the general area, a new volcano might push through the crust.

Off to the left, Goat Island Mountain rose on the opposite side of the White River Valley. According to Roadside Geology of Mount Rainer National Park and Vicinity by Patrick T. Pringle, this mountain is built of granodiorite and volcanic rock from the older Stevens Ridge and Ohanapecosh Formations. These rocks solidified from magma well before Mount Rainier, 28 to 36 million years ago. Yet, here that mountain is beside the much younger Mount Rainier, and one of Rainier’s lava flows is where my trail runs along Sourdough Ridge. Give me more gray matter, please!

A golden-mantled ground squirrel ran across the trail and up onto some rocks. A massive flow of andesite lava early in Mount Rainier’s history formed Sourdough Ridge. I jumped up and down a few times to ensure the rock had solidified. My friend looked at me like she thought I was crazy. It is mind-boggling to think of this ridge’s formation.

At the time, large Pleistocene glaciers came off the volcano and flowed down the valleys. Extremely thick ones, apparently rising to the height of this ridge, for lava flowed between two glaciers until it came to an ice damn formed where one glacier turned north and ran into another. The liquid rock pooled, eventually solidifying to create the area we now hiked. The trail ran across rock once a liquid lake of hot lava. That thought made me feel insignificant in time and space, but the opportunity to be here made my spirit soar.

At Frozen Lake, we had to decide: Should we head up to Burroughs Mountain, where the alpine flowers might be in full bloom, or take a different trail? The top of Burroughs would also give us an even more expansive view of her majesty. The park volunteer at Frozen Lake said we’d have to cross three stretches of snow and ice; a slip could be fatal. We took the trail to Burroughs, and the flowers were already beautiful.

Burroughs Mountain

At the first patch of snow, my friend said, “Use both poles, stomp with each foot, and keep your eyes on your toes; take it slow.” I steadied my knees and made sure never, no way, to look down into Berkeley Park. Thinking about how the lava flowed here and how subsequent glaciers might have carved its shape kept my mind from my fear. On top of that, the park service had somehow cut this trail into the slope. How had they been able to do that?

The flat plain of First Burroughs always makes me stop and stare. Partly, it allows me to catch my breath now that I am above 7,000 feet, but also because of the view. The sheer drop of Willis Wall to the right of the summit and Little Tahoma and Disappointment Cleaver on the left frame the peak. Steamboat Prow points right toward the summit like a small child in the middle, yelling, “Look, mum.” 

This view has been the same for as long as I’ve lived in the Pacific Northwest, but it hasn’t always been. Fifty-seven centuries ago, the mountain was taller, but how much taller is controversial. Some geologists think it was only a few hundred feet taller, while others say it was more likely a thousand feet taller. Some even believe it topped 16,000 feet or two thousand feet higher. 

Osceola Mudflow

Then, around 5,600 years ago, the east side of the summit failed catastrophically. Geologists calculated that 3.6 cubic kilometers of rock, ice, mud, and water crashed down, ripping the entire east side of the mountain off. Much like cement with boulders, a torrent of sludgy material swept down both branches of the White River. Within a few hours, the slurry, known as the Osceola Mudflow, had reached Puget Sound, covering over 200 square miles with thick sediments from the mountain. This mudflow is the largest lahar recorded for Mt. Rainier. Enumclaw is built on 19 feet of Mount Rainier mud. Comprehending the size of this flow is staggering. I estimated it would take six hundred million large dump trucks to haul that much, assuming each could carry six cubic meters. 

A recent article in the New York Times challenged us to spend ten minutes looking at a single painting. The “painting” before me had so much detail that I pondered for far longer. What chemistry allowed the rocks of Steamboat Prow, Mount Ruth, St. Elmo Pass, and Burroughs Mountain to resist being swept away? The mountain sheared along Willis Wall, and Little Tahoma stayed firm. Why? How many centuries did it take for Emmons and Winthrop Glaciers to fill the cuts?

Now, their ice is textured with crevasses, buckles, and drops. It is a complex mosaic. Could I see how climbers move up Emmons toward the summit? They walk up the Inter Glacier, over Steamboat Prow, and spend a night at Camp Schurman before attempting the final ascent. Were those tracks running up that one stretch of Emmons immediately left of Steamboat Prow? I’ll never know what the view might be from there, but my companion today had reached the summit.

I hadn’t brought my binoculars, so I only had a two-power telephoto lens to look for climbers. At this distance, they would be smaller than a gnat. Back home, I would blow the picture way up, zooming in as if I had a spotting scope. There, down from the summit, were eight climbers. The jealousy welled up in me. The necessary nerve and strength were never part of my repertoire. The photograph was taken a little before 1 PM. They were probably on their descent, having summited many hours earlier. 

The mountain’s spell broke so I could catch my friend, and we hung a left to head down the south side of Burroughs. The view was breathtaking, dropping thousands of feet to the White River. A geologist climbing near Baker Point on Goat Island Mountain discovered rocks from the Osceola Mudflow more than 1500 feet above the White River. The slosh of the slurry was like the wave one creates in a bathtub when moving too fast. It bounces.

We stepped to the side to allow four young people to pass. One commented on the geology, and I gave them a quick synopsis of what had happened here over the last half million years. She asked how I knew all that, and I shrugged. But her question made me think, and I turned to gaze at the current summit. Adobe Photoshop has added new Artificial Intelligence capabilities. One can select an area and then ask it to generate replacement options. I’d only used it to take out distractions, little things like a stick or hot spot. But I wondered if I came up with the correct set of requests, might this A.I. allow me to look at a possible view before the Osceola mudflow?

The Mountain Before the Osceola Mudflow

When I returned to Seattle, I explored this idea. I’d taken 33 portrait photographs to make a panorama. We were along Sourdough Ridge, and the sequence ran from Mt. Rainier to Goat Island Mountain. The resulting panorama again made me feel the magic of that day. On the trail, I’d wished for clouds, maybe a lenticular even, for it would have made a stunning photograph.

However, a cloudy day might have prevented me from playing with Artificial Intelligence. The geologic literature describes the various assumptions scientists have used to estimate Mount Rainier’s maximum height before the Osceola slide. Most have used the slope of the rocks on Little Tahoma and Willis Wall to draw lines to a possible peak above the current summit. Others have thought it might be more rounded and not that high. 

To make my selection, I used the slope of Willis Wall and Little Tahoma to draw a line over Mt. Rainier. Then, I dropped the selection down through the eastern side of Little Tahoma to run along Steamboat Prow, up and over it, and then along the edge of Burroughs before up to the right side of Willis Wall. The selection covered the area where 3.6 cubic kilometers of Mt. Rainier slide away.

My first few attempts at “directions” to the A.I. gave me views I couldn’t fathom as possibilities. The glaciers looked weird, the A.I. cut off the top of Little Tahoma, and the ice was too blue compared to anything current. I kept trying new directions, and when I used something like, “Make Mt Rainier taller with glaciers, snow, lava, and rock rubble,” it began to give me something more believable. The algorithm creates three options; I ran it twice, giving me six to pick from. I chose the one in the accompanying comparison. 

Is this what Mt. Rainer looked like from Sourdough Trail 5600 years ago? No way, but this exercise aimed to help me—and us—imagine what it might have looked like—something to ponder. Impressive, magnificent, and awe-inspiring come to mind. I shared these two photographs with friends who ascended Mt. Rainier in the last decade. One commented that the current view “looks easier to climb.” 

I can’t wait for my next trip, where I can stand near Her Majesty.