Wednesday, July 31, 2019
I saw the falls that grace the gorge of the Columbia River for the first time since my childhood last month. We were headed to Seattle to meet our students for our field studies course on the geology of British Columbia and we had stopped in Portland on our way north. I still had an hour or two before sunset so I headed east into the Columbia River Gorge to see the waterfalls that I hadn't seen in something like 50 years or more.
Monday, July 29, 2019
NOTE: If this post seems familiar, it should be. I posted it just a month ago. I'm re-posting (with minor changes) to place it in the proper order of the current blog series.
One of the vivid images in my mind of the Lord of the Rings Trilogy was the resting place of the Kings of Rohan. They were buried in mounds, and the mounds were covered by the white flowers called Simbelmynë. I couldn't help think of the Kings of the Rohirrim when we arrived at the Mima Mounds Natural Area Preserve near Tumwater, Washington.
Mounded topography forms in a number of places across the central and western United States in a number of different geological environments. Although they share some similarities, it is possible that they originate from several different processes. Ideas range from the mundane to the exotic (and unlikely). Most of them occur when a fairly thin layer of soil covers a harder layer or substrate underneath. They tend to be just a few feet high, and occur in concentrations of 8-10 per acre.
Occam's Razor states that among competing hypotheses, the ones that make the fewest assumptions are more likely to be correct (sometimes inaccurately described as the simplest answer is always the best). One of the more reasonable explanations for the mounds may be simply rodent activity. When pocket gophers dug into the shallow soils and encountered harder sediments, they tended to build up the mounds, and the process continued through thousands of generations. Maybe. And maybe it's aliens...
|I managed to catch a photo of the mima mounds on approach to SeaTac a few years ago.|
from the park website:
From southbound or northbound Interstate 5, take Exit 95 and turn west on Highway 121 (Maytown Road SW) toward Littlerock. In Littlerock, continue west (forward past the school, past the intersection with Littlerock Road that curves south, and past the mini mart/gas station on the right) onto 128th Avenue. Travel about 0.8 mile where 128th Avenue ends at a 'T.' on top of the hill. Turn right onto Waddell Creek Road and travel about 1 mile. The entrance to Mima Mounds Natural Area Preserve will be on the left. A Washington State Discover Pass is required for parking at this site.
Postscript: Dustin commented when I posted the original last month, and these ideas have some merit...
Great features! My guess is that the mounds developed when glacial outflow preferentially eroded the fissures created by patterned-ground permafrost in a periglacial environment. This photo shows mounds forming from patterned ground in Alaska.
In the case of the Mima mounds, if patterned ground was originally present with hard and frozen polygon centers, and margins/edges that were soft and thawed, then water flowing over the patterned ground would preferentially erode the fissures, while being less destructive to the polygon cores. Sustained flows would likely erode all evidence of patterned ground, but the Mima mounds were likely formed from ephemeral flow events associated with glacial melt near the ice sheet margins. This type of environment is suggested by the kettle lakes visible in the upper right of your airphoto, and the mounds being distributed amongst relict braided river patterns.
Sunday, July 28, 2019
It's not fair, but I don't spend much time in Portland, Oregon. It's not that I don't like Portland, I just don't know it because the logistics of my normal travels rarely allow me to stop there. We are always three or four hours away from our destination and worried about getting through town without getting stopped in one of Portland's legendary traffic jams. But on our way to meet our students in Seattle for our field studies trip to British Columbia we decided to stay in Portland, ostensibly to get nice pictures of Mount Hood. We were moving along Interstate 205 and the traffic wasn't too bad, and saw a wayside viewpoint and pulled off. It was there that I discovered for the first time the work of Tallapus (Coyote) to help the Clackamas people procure a secure food supply of salmon and lamprey: Hyas Tyee Tumwater, otherwise known as Willamette Falls. It's the second largest waterfall in the United States after Niagara. It's 1,500 feet wide, drops around 40 feet, and has a flow that averages about 30,000 cubic feet per second.
What? You've never heard of it? Neither had I. I would have thought that the second largest waterfall in the country would have attracted a bit more attention among travelers, but there are reasons that it is not all that familiar. Some of the reasons go right to the heart of cultural conflicts between European colonizers and the original inhabitants of the region.
The Willamette River is a major tributary to the Columbia, providing around 10-15% of its total flow. Major rivers don't tend to have waterfalls unless unique geological conditions exist. And the story of the Willamette is pretty wild. The river is one of the few north-flowing rivers in the country, following a geologic trough related to the actions of the Cascadia Subduction Zone. In other words, the valley of the Willamette River was not carved by the Willamette River. The valley is weird in some other ways...there are fine silt layers covering much of the valley floor, but scattered here and there are hundreds of gigantic boulders weighing as much as 170 tons. Boulders that came not from the adjacent Coast or Cascades Ranges, but from Montana and Idaho! How can these things be explained?
Between 15,000 and 13,000 years ago, the Pleistocene Ice Ages were beginning to wane, but an edge of the gigantic ice sheet that covered most of Canada flowed into Idaho and Montana and blocked of a major river drainage. A massive lake, now called Lake Missoula, formed behind the ice dam. The volume of the lake grew to 500 or 600 cubic miles of water, but then the ice dam destabilized and collapsed, sending a massive flood amounting to about ten times the combined flows of all the rivers on Earth racing across the plains of eastern Washington. The raging waters careened through the Columbia River Gorge at depths of hundreds of feet and the flows backed up into the Willamette River Valley. The muddy waters settled out, forming the silt layers covering the valley floor. The boulders arrived encased in icebergs in the turbulent currents. As the ice melted the boulders dropped out. The ice dam re-formed dozens of times and floods occurred at intervals of 50 or 60 years for around 2,000 years.
As the floodwaters receded the lava flows were exposed and then eroded by the waters draining from the Willamette. The ledges of lava became Willamette Falls.
|Source: By M.O. Stevens - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=6816704|
Most of these abuses are not visible from the overlook at Interstate 205. One wishes that with most of the ugly factories abandoned that the river and falls might be returned to a state resembling the primeval river. There are plans to "develop" the site with river walks and interpretive signs, but of course in the current culture of capitalism, also businesses and tourist attractions. It its own way tourism is a resource like any other, a commodity to be exploited.
In the end, I hope the stories will remain. The story of how Tallapus scooped out part of the river to slow down the migration of the salmon and lampreys so the people could catch some of them. And the story of how awesome, almost incomprehensive forces were unleashed by nature to form the falls through lava flows, glaciers, and gigantic floods.
|Source: Army Corps of Engineers|
Friday, July 26, 2019
The collapse of Mt. Mazama was an actual event around 7,000 years ago and it was witnessed and remembered by the inhabitants of the region who told the story above. Large volcanoes loom large in the consciousness of people, as they possess great power and have the potential for great destruction. Mt. Shasta is no exception, and even today a multitude of people tell stories of Lemurians, Atlanteans, and aliens who all seem to have an abode in the mountain somewhere.
Geologists are story-tellers too, although they tend not to invoke gods as a reason for the mountain's activity. They instead look for the natural laws of the Universe to understand how volcanoes work (in a sense those natural laws are the gods of the sciences). It may be that hundreds of years from now, our stories will be seen as quaint myths, but like all societies and cultures, we understand things through the prisms of our technology, mutual experiences, and observations.
Our students didn't actually see Mount Shasta, unless they saw it out the plane window. They all met us at SeaTac airport, but we had reasons to drive from California to Washington. Mt. Shasta is the foremost landmark in Northern California. It is at the southern end of the Cascadia subduction zone, and is considered potentially active (Lassen Peak is even further south, but we only had a brief view of it). It is a classed as a stratovolcano (or composite cone) and is composed mostly of andesite, a gray-colored intermediate silica volcanic rock. It has had eruptions roughly every 600 years over the last 10,000 years, with the most recent event probably in 1786. At 14,179 feet, it is the second highest Cascade volcano, but in volume it is the largest. There are five major glaciers around the summit, including Whitney Glacier, which at two miles is the longest glacier in California.
The volcano is actually a composite of four different cones of different ages: Sargent's Ridge, Misery Hill, Shastina, and Hotlum Cone. There was an even earlier version of Shasta dating to 600,000 years ago, but around 300,000 years ago the summit collapsed to form a gargantuan debris slide that traveled 28 miles north of the volcano, almost to Yreka. The lumpy hummocky surface visible around the Interstate 5 rest area near Weed is part of the ancient mass wasting event.
Shasta is visible from more than a hundred miles away, but as we continued north, the mountain receded from view. We got to Portland, Oregon, just in time to catch a few sights before the sun set. That story will be in the next post!
Saturday, July 20, 2019
The full Moon of July 16, 2019
This is the heritage of a country that undertook an audacious program of exploration under the leadership of JFK, and which succeeded through the exploits of courageous men like Neil Armstrong, Buzz Aldrin, and Michael Collins. What do our children dream of today? Is our education system inspiring them to strive for incredible things, or is it teaching them to be unquestioning automatons in a factory or office? Are we teaching them to be curious about the world, or teaching them how to take a multiple-choice assessment test?
I had the privilege today of offering a lecture on "Space Rocks" at the public library in Hemet, California. The audience turned to be mostly young women 6 to 9 years of age, so I changed gears and made it more of a talk about the adventures of scientific research, and how anyone, including them, could be the vanguard of our next journeys into the unknown.
In the words of the immortal folksinger Lee Hays (and no doubt others), all things, like a kidney stone, will pass. I believe that adventure still awaits us as a people. As I start a new school year next month, I am as excited as I have ever been to have the opportunity to introduce my students to an incredible Universe. And almost every teacher I know feels the same way.
version of a post from August 25, 2012 marking the passing of astronaut Neil Armstrong.
Friday, July 5, 2019
The Geotripper Blog has been quiet for a few weeks, due to the fact that we have been conducting a field studies course on the geology and anthropology of British Columbia and the Pacific Northwest. It's been hectic, but also incredible. Today though, I just had to find a moment to post about my experience from this morning. It has to do with spirit animals.
I don't accept the claptrap that emanates from the psychic/new age community about such things because it is a form of cultural appropriation, but when I encounter indigenous people who have close ties to a landscape that they have occupied for millennia, I pay a lot more attention. It's one thing to be a member of a privileged group whose ancestors were responsible for genocide of entire cultures and then to pretend to take their religion seriously, and quite another to try and understand and respect these cultures that have existed for many centuries.
During this trip, I've been deciding what animal would represent my place in the cosmos, and because I have been seeing a great many Bald Eagles, I "picked" them (understood easily by our students, given the fact that I spend my time looking at the skies above for birds while talking about the rocks below). But this morning we were touring the Squamish Lil’wat Cultural Centre in Whistler, British Columbia. The Centre celebrates the peoples whose traditional boundaries straddled the passes around Whistler, the Squamish (Sk̲wx̲wú7mesh) and Lil'wat (Lil’wat7ul). It is a wonderful facility and includes an outdoor area showing a pithouse and longhouse, as well as a forest trail identifying culturally important plants and animals. Including the sign in the picture below...
And not more than 150 feet away, there it was...a Black Bear foraging along the trail. It was being a "good" bear, looking for food from the forest rather than from the trash cans and litter of the people in Whistler. Frankly, it was just a bit eerie, but only a bit. The bear was unconcerned with my presence. It was mainly a moment of contact with the natural world that is all too rare in our deeply insulated society.
To them the bear symbolizes family and strength through motherhood and teachings. Mother Bears are fierce defenders of their children and are great protectors. Bear is a well-respected member of the community and is sometimes referred to as the protector of the forests. They look to the Bear to show them how to fish and pick berries in their territory.
The meanings of the other animals and spirits can be found here: https://shop.slcc.ca/legends-symbology/