Vagabonding on Dangerous Ground: In This Land of the Sasquatch There are Ancient Giants

Yep, the first part of our journey into Dangerous Ground took us to the land of the Sasquatch, the legendary ape-human of the Pacific Northwest forests. That's not him in the picture above, although I could understand the misinterpretation. That's actually me taking a rare selfie at the Golden Gate Bridge. We were only an hour into our journey, and we had 200+ miles to go, but we couldn't resist being tourists for a moment. It was a wonderfully clear day in the Bay Area.

Our real goal was to reach a part of ancestral California, the Redwood forests. The original range of the trees extended from the Big Sur Coast to the Oregon border, but the wood is durable and therefore valuable. The forests were removed and only a few intact forests remain, with only about 5% of the old growth groves left. Thankfully they are mostly protected, but there is still a sense of great loss as we drive past mile upon mile of either barren slopes, or slopes covered with brush and sometimes young redwood trees. But often not.

These trees are the tallest in the world. There are rumors from the past of 400 foot tall trees of other species, but the claims date from more than a century ago, and these supposedly huge trees were cut down. I don't know if loggers exaggerate any more than other workers, but who knows? I'm pretty skeptical of the claims, and they can't be tested. The tallest Redwood is 379 feet (115 meters), and it was discovered only in 2006. There may still be taller ones out there.

There is really nothing quite like wandering through a mature forest of Redwood trees. The sun may be shining, but the light at ground level is more of a diffuse emerald green. Once the sun gets low, the forest becomes gray, and then pitch-black. I have a hard time imagining orienteering in places like this. Landmarks can be hard to come by.

Because we were vagabonding, i.e. not really planning far ahead, we stayed at Humboldt Redwoods State Park only because I was able to score a late cancellation. We got two nights. We explored the old growth forest along Bull Creek, and had a close look at one of the truly giant trees, which is called (by some degree of coincidence) "Giant Tree". It's only 16 feet short of being the tallest tree in the world, at 363 feet (110.6 meters). It towered over us.

It was gigantic, but from the ground it was difficult to see how tall it really was. You can see it in the photo below, just a bit right of center. The picture was possible only because the tree was near the edge of the grove. If it were in the middle of the grove, we could have walked right past it without realizing how it towered above the other trees.

This new series is called "on dangerous ground", but in this instance the danger was more to the trees than to us. We were inland, far from the dangers of tsunamis, but not far enough inland to be threatened by volcanic eruptions in the Cascades. Giant earthquakes have no doubt knocked a few of these trees over, but some of these ancient giants have survived five or six of the magnitude 9 tremors that have shaken the region in the last 2,000 years. No, the real danger is us, and what we've done to this ancient forest.

About that Sasquatch thing. Of course I believe that a race of gigantic ape-people have managed to survive and stay hidden in these deep forests, leaving behind no traces, no tools, and only revealing themselves to charlatans and book authors. Of course I believe. I also believe that the range of Sasquatch sightings happens to correspond pretty close to the range of the Black Bear, but no one could possibly mistake a seven-foot tall bear covered in dark fur in a dark forest with a seven-foot tall ape-human covered in dark fur in a dark forest. Especially if one believes hard enough.

But belief, no matter how fervently felt, doesn't prove much...

Vagabonding on Dangerous Ground: Following the Cascadia Subduction Zone on Highway 101

Lake Crescent in Olympic National Park at the north end of Highway 101.

I'm sure that NO ONE in the various forms of mass media WOULD EVER stoop to using HYPERBOLE to increase their readership/viewership. You know, saying things like "THE BIG ONE IS COMING", that the GIGANTIC TSUNAMI is going to DESTROY EVERYTHING WEST OF I-5, that EVERYONE WILL DIE in the BIG EARTHQUAKE (or at some point decades afterward of old age). I would, for instance NEVER use capital letters in my opening paragraphs to try and catch the reader's eye. That being said, I really did have half of my trip completed before the media storm began concerning the chances for a magnitude 9 earthquake in the Pacific Northwest. I would have been describing my trip anyway, but the brouhaha over the possible earthquake and tsunami provides an opportunity to inject some level-headed geology into the discussion.

Route of Highway 101 through California, Oregon and Washington (red line). Interstate 5 runs parallel to Highway 101 just inland.

The fact is that the Pacific Northwest IS dangerous ground. But so is California. So is Oklahoma. And Minnesota. And Florida. And every bit of land across the world. There is nowhere that humans can live on this planet that is free of natural hazards. It doesn't work to go moving somewhere else, because no place is truly safe. The best we can do is to is to understand the nature of the threat, and to be prepared for the disasters when they happen.

The latest tempest involves a New Yorker article on the coming magnitude 9 earthquake along the Cascadia Subduction Zone. The basics of this potential earthquake have been known for nearly half a century, ever since the theory of plate tectonics came to be accepted by geologists. The details of a massive earthquake that took place in 1700 came to be known more than a decade ago. But it seems there is sometimes a tipping point when the public becomes aware of such hazards, and the New Yorker article seems to have done the trick. People in the northwest are talking earthquakes and tsunamis. The Cascades volcanoes must be feeling very neglected right now; they were once the main topic of any discussion of geologic hazards in the region.

The Juan de Fuca and Gorda crustal plates, among the world's smallest. The Cascadia Subduction Zone is the black line with the converging arrows. Many of the most important Cascade volcanoes are shown as red triangles.Source: NASA

So our journey quite literally was an exploration of nearly the entire subduction zone, as seen from U.S. Highway 101 and Highways 1 and 99 in British Columbia. As can be seen in the diagram above, the zone begins near Cape Mendocino in Northern California and extends to Vancouver Island in British Columbia, Canada. The highway parallels the coastline, and follows the coastal terraces and beaches in many places, especially in Oregon. We spent ten days making our way north from San Francisco to Canada and northern Washington, and three days heading home again along Interstate 5. We camped when spots were available, and stayed in hotels (if we had to).

Interstate 5 is a freeway from Mexico to Canada. It's a fast and efficient way to get from one place to another (except for the traffic jams in Seattle and Portland). But it's also not very interesting over much of its length. Highway 101 is more a patchwork of freeways, highways, and two-lane roads, and because of the challenges of the geology it is a route to be followed in a more leisurely manner. It is far more scenic, and for that manner, more dangerous in the geologic sense. It's never a surprise to see signs referring to falling rocks and tsunami evacuation routes.

Side view of the Cascadia Subduction Zone (source: U.S. Geological Survey)

The source of all the geological mayhem is one of the smallest crustal plates in the world. The Juan de Fuca plate forms a few hundred miles out in the Pacific Ocean where new basaltic lavas emerge from an oceanic divergent boundary. The plate moves east at a rate of few inches per year. It then dives beneath the North American Continent, where the buildup of frictional stress results in earthquakes, both big and small. Eventually the plate begins to melt, releasing plutons of molten rock that sometimes leak out at the surface, forming the Cascades volcanoes like Rainier, St. Helens, Crater Lake and Shasta.

Source: http://crew.org/sites/default/files/cascadia_subduction_scenario_2013.pdf

I imagine you could be thinking "what's the difference between this blog series (Dangerous Ground), and my just completed series (Driving Across the Most Dangerous Plate Boundary)? The facetious answer is, of course, that in this series, we will be driving along the plate boundary instead of across it. But the more serious answer is that the ancient Cascadia Subduction Zone in Central California is extinct. It stopped activity tens of millions of years ago. The subduction zone of the Pacific Northwest is presently active, and capable of causing catastrophic damage. And the landscape is different in many ways. In the series I plan to talk about the geology, of course, but I also find it to be a land of majestic beauty. That's the thing about geological hazards; they may be dangerous and cause human catastrophes, but they also result in some of the most spectacular landscapes on the planet.

A Bit of River Perspective: The Eel River in Northern California

I was driving home from our Christmas visits with the family in central Oregon today. Since we were following Highway 101 through northern California's Redwood Country, we had a chance to look at the Eel River after several days of fairly intense rain. The picture above is a summertime view of the river from 2010 for sort of a baseline for comparing. As we drove along the river today I noticed it was filling the channel and inundating a fair number of trees. I wasn't thinking that it was flooding exactly, but it was full of sediment and moving fast. We stopped to grab a few pictures.

The river today was flowing at about 10,700 cubic feet per second. That would be flood stage on our own Tuolumne River, but was an unremarkable amount of water comparatively speaking. On Christmas Eve it was just over 20,000 cfs. We stopped at Miranda and had a bit of a shock. Some government entity had painted a river gauge on the bridge column to provide a bit of perspective...

You can click on the picture to see the writing better, but it essentially shows the depth of the water, which today was 14 feet deep. It's not considered to even be flooding until it reaches a depth of 33 feet, which would be a flow well in excess of 50,000 cubic feet per second. But a flood that size would be miniscule compared to what happened here in 1964; the water depth at Miranda was 46 feet, equivalent to 200,000 cubic feet per second. Downstream at Scotia where several forks of the river had combined, the water topped out at an unimaginable discharge of 752,000 cubic feet per second.

Needless to say, the damage was incredible, with entire towns being washed away. According to the Department of Water Resources, the North Coast rivers dumped 10.4 million acre-feet of water into the Pacific Ocean in six days. For comparison, Lake Powell on the Colorado River, a 186 mile long reservoir, holds 27 million acre feet. The average yearly flow of the Colorado is 14 million acre feet.

Perspective....