Saturday, August 5, 2017

When Life Gives You a Single Point of View, Milk it For All it's Worth: Crater Lake in June

It never fails. I secretly control the incidences of drought and flooding in the western United States. How? By scheduling our summer field studies a full year in advance. The proof? Every time I schedule a Southwest trip, the climate changes to long-term drought, and it is a hot summer. Every time I schedule a trip to the Pacific Northwest, the drought breaks and we have record snowfall in the winter that doesn't melt until well into the summer. This was the case in 2011, our last northwest trip, and it was the case again this summer, in 2017.
In 2011, we saw that Crater Lake was snowbound, so we didn't even try to go there, heading into Newberry Crater instead. Even though somewhat lower, it was buried in snowdrifts as well. It had now been more than a decade since I had laid eyes on Crater Lake, so I planned the visit anyway, even though most of the roads were closed, and we would have to backtrack 80 miles off our trip route.
The only problem with having a single point of access and only a few parking lots plowed of snow was that only so many people could be accommodated in the park at a time, and June's massive heat wave was just getting started. People wanted to cool off, so they headed up into the mountains to Crater Lake. As a result spent 45 minutes in line at the entrance station, and our four vans were on their own for parking. We radioed each other to meet up at a rendezvous point near the rim once parking site was secured. So it was that instead of exploring a national park, we had the singular opportunity to view it from just one part of the rim.
And yet, what a sight it was! Just the dimensions are stunning. The lake is six miles across and 1,949 feet deep (542 meters), the deepest in the United States, the second deepest in North America, and the ninth deepest in the world (Baikal in Russia is the winner of that race, at 5,387 feet, or 1,642 meters). The deep blue color of the lake follows from the clarity of the water, which has been measured as deep as 175 feet (53 meters). It's not just the reflection of the sky above (note that the sky is lighter than the lake surface). The clear water absorbs the longer light waves at the red end of the spectrum, but scatters and reflects the shorter waves at the blue end of the spectrum.

The "crater" of Crater Lake is not a crater in the usual sense. It is a world-class example of a caldera, a volcanic feature that develops when a huge volume of ash explodes out of volcano, and the summit sinks into the void left behind. It was an unimaginable catastrophe. In the space of a few hours or days around 15 cubic miles of ash and debris were blasted into the atmosphere from the summit area of Mt. Mazama, the name given to the former volcano that became Crater Lake. What had once been a volcano as tall as 12,000 feet was now a smoking ruin with a rim barely exceeding 8,000 feet. The bottom of the caldera was another 4,000 feet lower. The ash was spread across the western United States and Canada, providing a crucial dating horizon for archaeologists (the ash has a unique chemical composition that can be identified in dig sites).
The lake itself, of course, came later. It is estimated that it took around 700 years for the lake to fill the depression to the level of the current day. There is no inlet or outlet. Water comes from snow and rain, and the level is balanced by evaporation and seepage (there are numerous springs around the flanks of the volcano). Fish are not native to the lake, but several kinds were introduced over the years. They don't do particularly well because of the purity of the water (there are few nutrients to support a food chain).

The Crater Lake caldera is young in the geologic sense, having erupted 7,700 years ago (+/- 150 years). Think about that: the ancestors of the indigenous people of the region saw and experienced this event. Their oral histories of the Klamath people recall the event. How many cultures in in today's world have collective memories that date back that far?
One might wonder if any eruptions from recorded history can match the violence of the Mazama eruption 7,700 years ago. It turns out there is. In 1815, Tambora, a 14,000 foot high volcano on the island of Sumbawa in Indonesia exploded with a fury equivalent to that of Crater Lake. The summit collapsed into a caldera in the manner of Crater Lake. After 200 years, a lake has begun to accumulate on the caldera floor.

Tens of thousands of people on the island died from the eruption itself or starvation later (all vegetation on the island was destroyed). So much ash was blown into the atmosphere that the climate cooled to the extent that snow fell during the summer months over much of the northern hemisphere. Famine contributed to hundreds of thousands of deaths around the world.
When we visited the park, the lake was still covered by snow, and crowded with tourists, but none of that could obscure the incredible story told by the rocks and water. The Cascade volcanoes are capable of great violence. The eruption of Mt. St. Helens in 1980 killed around four dozen people and did a billion dollars in damage, but the volume of that eruption was only about 1/60th the size of the eruption of Mazama 7,700 years ago. It's hard to imagine the effects of such an eruption in today's technological society. Would we be talking about it 8,000 years later?

Post a Comment