Flaming Geyser State Park
The park is located at the upstream end of Green River, where it enters a gorge. This is one of the best places I’ve seen anywhere for taking a stroll through nature; the path is moist but not muddy, and well trimmed, with breathtaking natural scenes like this. A veritable Garden of Eden. This post is an overview of the park; I discuss the geology and flora in other posts.
With a name like that, I’m expecting a spectacular show…
I’ll summarize what you can read if you zoom in on the information presented in this billboard. An exploratory well was drilled here about 100 year ago, looking for coal–they found it, along with methane (natural gas) and other gases produced by decaying vegetation at several hundred feet below the surface. The small well produced a flammable gas that has burned intermittently since it was first lit by a geologist.
Flaming geyser wasn’t very active when we visited, but it was burning. To repeat, this is NOT a natural seep, but the result of a well drilled a century ago. Nevertheless it has become a local tradition, and it is relit whenever it goes out.
Bubbling geyser is a lot more fun. This video shows small bubbles of methane, as well as hydrogen sulfide and other, unnamed, gases. Methane is odorless, but this area smelled strongly of H2S, which is added to natural gas to help detect leaks.
This is a beautiful example of survival. The surface roots have all been exposed by erosion, but the tree is thriving; its roots have turned into separate trunks. I read somewhere that these conifers in the PNW send their roots out for hundreds of feet, far beyond their canopies.
This is where Green River Valley turns into Green River Gorge. The water was perfectly clear, with a slight green tinge, even though there is no algae visible. It reminds me of Commencement Bay, which is also devoid of aquatic plants. And it is all natural, simply a unique ecosystem.
If you wear waders, you can walk on water here.
Final Thoughts
This is a place you have to visit for yourself, especially on such a gorgeous summer day. The temperature was in the mid-seventies, the sky was clear, and people were filling the huge number of picnic areas, carrying their supplies and tubes, ready for a fun day of floating down one of the best rivers I’ve ever seen.
You’ve got to see it for yourself.
Eocene Continental Sediments in Flaming Geyser State Park
Figure 1. Flaming Geyser State Park is located along the Green River (see Fig. 2 for location), where its valley narrows and deepens. This photo shows a typical gravel stream, but there is plenty of sand and even clay available to construct a flood plain. The alluvial deposits downstream are rich farmland, where we saw a variety of vegetables growing.
Figure 2. (A) Location of the study area SE of Tacoma in the foothills of the Cascade Range. (B) Green River has eroded a valley in the glacial till and bedrock along its path. The northern margin is steeper throughout its length. Flaming Geyser State Park is located upstream of the arable land, where the river becomes rocky and the valley narrows to a gorge. (C) The geologic map from Rock D reveals Eocene (56-33.9 Ma) continental sedimentary rocks along the stream bed whereas further north, Vashon till of Pleistocene age (2.58Ma – 11.7 Ka) covers the region in a thinning-eastward blanket. Just south of the river itself, Quaternary (2.58 Ma – Recent) fluvial and alluvial sediments have accumulated.
To the extreme east side of (C), a fault line can be seen running N-S. Faults are common, but often difficult to identify, within the region because the Cascades are the result of oceanic-crust subduction beneath the North American tectonic plate.
Figure 3. These layers of Eocene terrestrial sedimentary rocks have been tilted eastward (to the right), towards the fault seen in Fig. 2C, suggesting that it is a normal fault; however, their beds aren’t quite continuous, suggesting some slippage between them. The patches of foliage separating them may indicate minor faults, where the rock is ground into fine material suitable for plants to thrive. For example, the leftmost exposure is similar in stratification to the middle strata of the center exposure; the rightmost exposure doesn’t seem to be continuous with either, except for the thin, resistant bed immediately below the cliff on the right, and a similar “marker” bed a few feet lower in the middle exposure.
Following a horizontal line between them, the rocks are younger to the left, but not by much–possibly a few thousand years. This brittle deformation would have occurred a few miles within the surface when the faults were active; unfortunately, faults cannot be dated with precision.
Figure 4. This is an interesting sample, which required some thinking, and a conversation with ChatGPT, to arrive at the most plausible explanation for the irregular blobs of darker material protruding from a reddish matrix. I’m pretty sure this texture arose from mingling of magmas with different compositions: the reddish one is andesite, and the darker material is something closer to basalt (there is a spectrum of chemical compositions); they were incompatible, but the magma wasn’t hot enough to totally incorporate the more basaltic material into the andesite.
We are seeing magmatic mixing processes frozen in time here.
Figure 5. This photo reveals a cliff of Eocene sedimentary rocks across the river, probably 100 yards distant. I zoomed in to reveal the bedding. I estimate the height of the gray rock visible through the foliage to be at least thirty feet. The lower section contains two sets of cross-bedding, separated by an erosional surface, brought into relief by differential weathering. These large bed forms were created by water, probably in braided rivers or high-energy channels. The flow was to the left, westward in general.
This environment persisted for a long time although these rocks can’t be dated (no fossils or organic material); if we assume either a deposition rate of 1/8 inch per year (that’s a lot of sand), or a subsidence rate of similar magnitude (to make room for this stack of sand), we can estimate how long it took for 30 feet of sand dunes to accumulate. When we do the math, we see that this section could have been created in about 3000 years. This calculation is for illustration only. We don’t know the actual sedimentation rate here during the Eocene, nor do we know the amount of erosion.
Figure 6. This photo from the south side of Green River shows some highly fractured rock beneath a stronger layer that forms a one-foot overhang. The overlying rock is staining the subjacent layers with a rust-colored material, probably from weathering of iron-containing minerals. Are these beds equivalent to those from Fig. 3?
I don’t know the answer, but the contact revealed in this photo is similar to that between the massive, cliff-forming rock from the rightmost exposure in Fig. 3, and the lower, gray layers. I wouldn’t be surprised if this rock is similar in age and environment as the gray rocks across the river.
Final Thoughts
Sometime, more than thirty-million years ago, large rivers drained the Cascades, depositing vast quantities of sand in braided rivers many miles from the coast, where finer sands and silt slid down submarine canyons and fans to be deposited as turbidites. I talked about those rocks in a previous post. Comparison of these rocks and those along the Olympic Peninsula coast allow us to reconstruct this small part of the world from a bygone age.
These Eocene sediments are similar to those we discovered a few miles to the south, along the Carbon River. This sedimentary environment wasn’t a local event, but rather part of a regional system that continuously removed the volcanoes and older rocks that were exposed by the upward pressure of the Pacific Ocean’s subducting slab. This was not an intermediate environment.
The wide range in dates for these rocks doesn’t allow geologists to be more specific than a few million years, but the earth doesn’t act very quickly, especially when the subduction zone that determines the geology of the PNW has been active for almost 200 million years.
We can afford uncertainties of a few tens of millions of years…
Review of “Eyeless in Gaza” by Aldous Huxley
This was a difficult review.
Gaza is never mentioned in the book, but apparently (according to ChatGPT) it is taken from rom Milton’s Samson Agonistes. How appropriate. I never read Milton, but its fundamental influence supports the theory that this book is a pseudo-autobiography. I admit to bias when I saw Huxley’s picture, in his thirties (maybe?) on the back cover. He looks like the central character … let’s get to it.
This is a troubling story about a young man who is a member of the British elite in the 1930s. Anthony Beavis is an intellectual who finds hedonistic pleasure in reading and seducing women. He is not pleased with his lifestyle, but it satisfies his urges, so he sees no reason to change. The conflict arises as he recognizes the dissatisfaction he feels from this lifestyle. That’s where the story begins to fall apart.
The story of Anthony’s self-realization is one of disillusionment in his social status. The story is told, not in actions, but rather by inaction. He can never act, not because he doesn’t know the proper response to events, but because he is encased in concrete — social and personal. The entire novel is about his struggle with recognizing other people as being human and not objects to be avoided or exploited. This makes the author’s job more difficult because he must try to change Anthony without invoking supernatural effects.
He fails in this primary objective, in my humble opinion. The protagonist (Anthony) never truly confronts the obvious problems with his social behavior.
Anthony himself says that divine intervention caused him to meet Dr. James Miller, a physician who just happened to be approaching the hamlet where Mark was dying of gangrene. I have seen this kind of writing time and again. How do I transform this incorrigible person into the saint I want them to be? No problem. Invoke a miracle. Voila! Anthony is a new man, except …
The story ends with the same old Anthony, but with a slight adjustment: he is willing to risk his life for something he doesn’t really believe in.
The grammar is okay but relies, to an excessive level, on commas. I think Huxley lost track of some of his prepositionally dominated sentences. I’ve seen that before.
This is a story that follows a meandering path through the past to lead to a present that is no different from the past. Maybe that was the author’s intent. We struggle with our thoughts but fail to control them, barely managing, if we’re lucky, to nudge them in a slightly different direction.
I recommend this novel to anyone who has ever wondered if other people are as confused and misinformed as them.
A Quick Visit to the Lemay Family Collection
I visited the Lemay Family Collection of automobiles. It is affiliated with the Lemay America’s Auto Museum, but it more low key. Nevertheless, it contains a lot more than antique cars; this post is sharing some of the more mundane aspects of the development of automobiles as a major form of transportation.
The lower shelf of motor oil contains many familiar products; but the upper shelf will probably get your attention. How about putting some skunk oil in your motor? I wonder about their marketing campaign. Note that there are no plastic bottles here; every container is 100% recyclable, heavy cardboard (not corrugated) and metal rings.
I discovered the motometer recently. These devices are thermometers mounted to the radiator cap, which was exposed until the late 1920s. This is an assortment of these important gauges but, unfortunately, they aren’t labeled.
The major oil companies started adding tetraethyl lead to gasoline to prevent premature detonation in the 1920s, but they knew lead was dangerous, so they formed a new company called the Ethyl Gasoline Corporation; the word “lead” never appeared in advertising, but people loved the new gas, even though they had no idea what was in it. They thought it was high octane. You gotta love mass marketing in the twentieth century.
They don’t make BMWs like this anymore. Note the door on the front.
This is a horse-drawn road grader. Th operator stood on a missing platform and turned the wheels to adjust the blade. Some of them were adapted to be pulled by tractors. Not a very satisfactory solution …
This is a motorized road grader from 1925-1930. The gasoline engine is beneath the large tank in front of the cab. It was basically a tractor with an extra axle behind, and a long frame in front. This was before hydraulics were available, so the controls are all manual.
This is a Fordson road roller circa 1930-38. Note the smooth engine, reflecting the art-deco design craze sweeping the country.
ChatGPT and I agree that this is probably a road oiler (for asphalt surfaces) from the 1930-50s. We’ve all seen trucks with large tanks spraying oil on asphalt roads.
I recently posted about hood ornaments over the decades after a visit to the Lemay auto museum. This one, from a 1937 Packard 120 Coupe, caught my eye because the winged, female figure seems to be holding a wheel and tire assembly or maybe a disk. This is one of two optional ornaments, the Goddess of Speed; the other was a cormorant. Optional hood ornaments! Who would have believed it.
Final Thoughts
I always enjoy looking at old automobiles because they reflect the non-military development of a new technology, unlike aircraft. Part of this evolution was progress in road machinery — cars need good roads, unlike horses and buggies.
Disarray Along Commencement Bay
This morning we went for a walk along the western shoreline of Commencement Bay, which was home to many sawmills, even a smelter, between the 19th and late 20th centuries. Rather than removing all of the industrial debris, the city has left the remaining infrastructure as a kind of museum. There are signs explaining a lot of the history and even a piece of sculpture integrated with an original saw.
The shoreline is a dynamic environment where plants struggle to keep up with the sea and weather. Thus, pioneer plants dominate the flora.
This view is looking to the NE. This is the last sawmill site along the bay, but it doesn’t have any signage explaining its history. Nevertheless, this image, taken at low tide, says a lot: The large concrete structure was the foundation for a piece of heavy equipment like a saw or winch; the piling stubs reveal where it was connected to land, where a receiving platform (left of image) was constructed. The remnants of a dock are in the lower right. There are a line of pilings further seaward that demarcate a dock that would have served as a wharf for ships.
Most of this structure would have been submerged at high tide (7-10 feet, twice a day). This reinforced concrete structure probably was the base for the saw, the channel likely designed for pulleys, chains, etc, that ran the saw or pulled trees (up to 14 feet in diameter) into it. The sawmills often located their saw heads offshore to make processing logs, which arrived by raft, easier.
This bramble caught my eye, so I took a closer look. It is a mixture of two pioneer plants. Sweet peas of different species are native to the PNW (I don’t know which exactly this is), but Himalayan blackberry is invasive and threatens ecosystems across the region. They are fighting it out, so I’m cheering for the sweet pea — to fend off the foreign invader.
This wild rose species caught my eye because of the huge fruit (golfball sized), which is apparently edible. Just put enough gravy on it and it’ll taste fine.
I thought these bright, yellow flowers looked familiar. I checked a previous post to discover that the flowers are not common tansy. The flowers are curved upward and the centers are large, orange domes. It is invasive and toxic to animals (and people), so it is actively monitored. This example is growing in a thicket along with Rugosa Rose, which is also invasive; and yes, there are native plants that thrive in a coastal environment but they have natural controls that are lacking for these alien species.
Final Thoughts
I didn’t mean to photograph anything today, but the flowers are so eye-catching. And I love old industrial sites.
The Northwest Native Garden
Like the (rare) sign says: Trillium likes moist coastal forests.
This common PNW shrub thrives in moist coastal forest environments.
Vine Maple is an understory tree, which doesn’t grow high enough to compete for full sun; instead, it grows beneath the conifers and gives even more shade to the shrubs. This sapling is just starting to get some height. Moist coastal forest.
This is Salal (Gaultheria shallon). It grows in an environment similar to Vine Maple, in nutrient-rich, well-drained soils, often near water. Moist coastal forest.
This shrub forms colonies in mesic forest patches, where partial sun is available although it is shade tolerant. The identification is difficult because of so many plants with similar leaf shapes, but I agree with CoPilot. A denizen of moist coastal forests.
This plant is common to shrub thickets and riparian edge habitats.
This distinctive plant is Bigleaf Lupine (Lupinus polphyllus). It thrives at the edges of meadows in a full-sun environment with moist to dry soil. Those lovely appendages are seed pods, so I don’t know what the flowers look like. This plant thrives in prairie/oak woodland habitats.
This slender, flowering plant is thriving in the prairie section of the garden. Prairie/oak woodland environments.
This vine is Perfoliate Honeysuckle (Lonicera caprifolium). It is a non-native variety that is commonly planted on trellises and fences. This one was hard to identify; CoPilot failed completely but, with help from Claude (Anthropic’s AI), we finally figured it out. We could still be wrong, however.
This flowery shrub grows in meadows like the micro-environment at the Northwest Native Garden. Prairie/oak woodland habitats.
These non-native (to Tacoma) columns of volcanic rock show up everywhere in the PNW. They originate within the Cascades Range, near volcanic vents and volcanoes.
This lovely flower, growing through some ferns, is Douglas Aster (Symphyotrichum subspicatum). It is common in moist meadows and forest edges. I verified the identification from CoPilot. Common in moist woodland/forest edge habitats.
There is a small, articficial stream flowing through the garden and feeding a small pond. I don’t know where the water comes from … is it natural or recycled? No idea.
This is a rare non-native species planted in the garden for contrast. I checked this myself, and this variety is variegated.
Final Thoughts
The Northwest Native Garden is a great place to see many of the ecosystems in the PNW in one place. However, the lack of identification is a problem, which I addressed using CoPilot. But I had to check it a lot because it is a Large Language Model, not a specific plant-identification model. Nevertheless, it always got me into the ballpark; and it is easy to work with, like collaborating with a human who knows a lot but tends to jump the gun sometimes.
We spent about an hour strolling through four PNW environments, which was a lot easier than driving around. It reminded me of a Japanese garden, like the one in Portland. Very peaceful and colorful.
I hope that anyone who got this far enjoyed my trip through the Northwest Native Garden as much as I did. I plan to revisit it and learn about some more native PNW flora.
The Foothills Trail along Carbon River, Pierce County, Washington
This post is a humorous (I hope) addendum to my posts on the geology and flora of Carbon River. I have noticed a lot of quirky, regional trends, both in decoration and signage, here in the Pacific Northwest (PNW) during our nature walks. The Foothills Trail was no exception.
There are several access points to the trail, but this was the only sign. It ends with a serious warning: Use at your own risk. What lies ahead in that darkness?
A couple miles downstream from the “official” trailhead, we stopped along the Carbon River. This is a piece of ubiquitous columnar andesite that was apparently placed here as a decorative piece. Unfortunately the sign is long gone.
The trail is wide and easy to access on foot. I don’t know about a wheel chair although it is flat all the way.
We saw several of these marker stakes along the trail. I looked it up and, to the best of my knowledge, this is indicating a tree where a pair of Marbled Murrelets are nesting. They are an endangered species and extremely difficult to locate, but there is an ongoing survey program. That sounds reasonable to me; the sign gives both a distance and compass heading to the tree.
The trail intersected the Franklin Bridge, which is indefinitely closed to traffic.
We climbed a steep slope, with the help of sturdy handles attached to wire rope, and took some photos on the bridge.
After we finished on the bridge, we passed the concrete blocks obstructing the road. Several signs made it clear that the bridge is closed to cars, bicycles, and pedestrians. Apparently someone disagreed with the DOT restrictions, and modified the sign. Don’t ask me why the figure is carrying a gas can that says, “Oh ya fuck ya.” I guess they’re thumbing their nose at anyone who would dare condemn what looks like a perfectly useful bridge — at least for people and wild animals.
We walked the three miles back to our car along the abandoned road. There were several rock falls and damage to the guardrails. In this image, a large boulder smashed through the eroded roadbed. It was like a post-apocalypse movie. Pretty cool … and quiet.
These relatively new signs were posted randomly on trees on the hill of the road. Hazards. Not hazard. Maybe Western Rattlesnakes, poison ivy or … dare I say it? Bigfoot. Stay out of the woods. But we just walked three miles through the woods. Damn!
These opposite-pointing signs were on a curve. Nevertheless, I have to wonder why the guardrail stops in the middle of the curve, but reflective signs were felt necessary. Short sightedness? Budget constraints? Stupidity?
The Flora of Carbon River, Pierce County, Washington
Plate 1. Our first stop was at Carbonado, where the Carbon River exits the canyon that has constrained it from its origin on Mt. Rainier. It immediately forms multiple channels as it cuts through glacial till on its circuitous path to Commencement Bay.
Plate 2. This lovely flower is red clover (Trifolium pratense), a common wildflower along rivers.
Plate 3. CoPilot and I argued too long about this one, but, after some back and forth, I decided it might be a genus of Spiraea. They are another common shrub in this ecosystem, but they aren’t in flower in July. Note the shriveled flowers in the right image. Too late to be sure. That’s why I’ve always ignored these bushes.
Plate 4. Cow parsnip (Heracleum maximus) is a common wildflower in meadows and roadsides in Washington.
Plate 5. Tansy (Tanacetum vulgare) is a common wildflower along the Carbon River corridor.
Plate 6. I thought, when putting this post together, that this was red clover (Plate 2), but CoPilot identified it as Canada thistle (Cirsium arvense). It loves disturbed areas like river edges. I did detect some spines when I zoomed in on the second photo. Why am I not surprised? If it’s pretty it will have spikes ready to draw blood from any inquisitive passers by.
Plate 7. This view is looking downriver from Franklin bridge, which is permanently closed. I’ll now describe some of the flora we encountered as we followed the river along a steep slope.
Plate 8. I (kinda) got this one right. This is a wild rose, Nootka rose (Rosa nutkana). This is another plant that waits for an opening in the forest canopy to grow, and then it colonizes like crazy — until the forest canopy catches up with it. Moist but well-drained soil pretty much sums up Carbon River canyon.
Plate 9. This familiar flower is foxglove (Digitalis purpurea), introduced from Europe; but it is so naturalized that it behaves like a native plant, similar to Cascade penstemon (see Plate 11), thriving in disturbed ground at the edge of conifer forests and in temporarily sunny areas.
Plate 10. Besides white flowers, I am also fixated on thorns; however, I don’t know anything about thorns except that roses have them, as well as many of the shrubs I’ve encountered on my nature walks. This is probably Himalayan blackberry (Rubus armeniacus), an invasive species to Pierce County. I guess that’s why it isn’t called Washington blackberry, or some such. I checked a previous post from Point Defiance, and there it was! Invasion of the forest snatchers.
Plate 11. This purple wildflower is probably Cascade penstemon (Penstemon serrulatus), a native to the PNW. It is what CoPilot calls an ecotone plant — one that thrives where a conifer forest is encroaching on a prairie environment. We encountered it where the conifers hadn’t yet blocked out the sun along the trail.
Plate 12. I’m easily fooled by white flowers. This non-woody shrub is False Solomon’s seal (Maianthemum racemosum). It grows in the understory of a conifer forest, which is a good description of Carbon River canyon.
Plate 13. This is the first triplet I’ve seen from a nurse log. These young hemlocks will certainly compete for sun and nutrients. There can be only one survivor.
Plate 14. I thought this was cow parsnip, but CoPilot identified it as ocean spray (Holodiscus discolor). The white flowers were all I needed to see, but this tall, woody shrub (6-12 feet) is completely different from the weed in Plate 4.
Final Thoughts
The only thing I can add to the photos is that Carbon River is part of a transitional ecosystem, not unlike Mima Mounds. I Imagine this borderland environment is also alternating between a lowland/prairie and an upland/conifer forest, depending on conditions. However, much to my disappointment, the plants here were different from those we saw before. Furthermore, there were far more species along the Carbon River corridor. We were fortunate to visit when many of the flowers were in bloom.
I enjoy taking pictures of flora and learning about the ecosystem, but this is too complex for me. I’m only a simple geologist.
The Flora of Point Defiance Park
This beautiful, mature second‑growth coastal temperate rainforest is only ten minutes from my house. I should get there more often, and perhaps I will after taking an interest in ecosystems in addition to geology. Today’s outing was an opportunity to begin acquainting myself with the ecosystem I inhabit, so I made an effort to identify several plants along Five Mile Drive, a road that circumnavigates the forest and is permanently closed to auto traffic. When I started walking along this path, this forest was nothing but a lot of green trees and stuff. My perspective changed over an hour or so, and about 2.5 miles.
This colorful maple tree is a native to Puget Sound. It earns its name because those deeply lobed leaves are up to a foot across. But what are its roles in this forest? CoPilot had a lot to say about that. The Big Leaf Maple is fundamental to this ecosystem because it creates a huge amount of leaf litter that contributes to the forest floor and thus supports a vast microbiome, as well as a nurturing environment for conifer seedlings. This large tree (50-150 feet) fills in gaps in the forest canopy, supplying shade and catching rainwater, as well as dew. Its dappled shade creates a diverse understory for new growth. It is important in the success of birds, insects, bats, squirrels, and deer. They all hang around it and depend on its large mass for homes and meals. Its large root system contributes to hydrologic stability by stabilizing slopes, slowing runoff (and erosion), retaining moisture, improving soil infiltration.
This large tree is native to SE Europe and they were introduced after the logging boom led to immigration. However, it is not an aggressive invader; this lovely tree does not form thickets, outcompete conifers, spread wildly, alter soil chemistry, suppress understory diversity, or create monocultures. In CoPilot’s words, “It’s a polite non-native.”
This nondescript shrub gives the forest its lush, evergreen understory identity. It is one of the top berry producers in the Puget Sound lowland forest but, more importantly, its berries ripen later in the season, extending the berry window into early fall. It also thrives in the acidic soils Douglas fir and hemlock create, in turn moderating soil conditions. It bridges the gap between ecological disturbance (i.e. logging) and late-successional forest. One could say that it serves as a node in the forest’s ecological web. This is an unrecognized keystone species in the understory.
Oregon grape is the huckleberry’s silent partner in keeping the understory secure because it is also an evergreen shrub. In addition, it supplements the food web by blooming in March-April, providing nectar when few other shrubs are in bloom. Its berries ripen by mid-summer, bridging the gap between early berry producers like salad and late huckleberries. It precedes huckleberry in forest succession but persists as the canopy creates a shadier understory.
Himalayan blackberry is less like the fruit-bearing huckleberry and Oregon grape, and more like the Trojan Horse. The fruit are abundant and sweet, produced for a long season, and loved by all the denizens of the forest; thus, they are spread like wildfire, colonizing the entire forest–without predators in Pt. Defiance. The result of this invasion includes impenetrable thickets, root masses that choke other species, spreading by long, arching canes, and monocultures. It kills all the other stabilizing shrubs and creates a single mass of Himalayan blackberry. If left unchecked it can destroy an entire ecosystem, including the conifers. Holy shit!
This nitrogen-fixing tree is the first responder when the forest is disturbed. As such it enriches soil, accelerates forest recovery, feeds the next generation of conifers, increases understory diversity, boosts fungal activity, and generally improves growth rates of proximal plants. Alder is the first tree to reoccupy damaged land, preparing the site for the conifers that will come later. Wherever alder stands exist, the biodiversity of the forest is increased. Because it gives so much to the forest, alders only live 40-60 years, thus acting as a continuous healing agent as a forest recovers from an environmental shock. This is the pioneer tree of the lowland forest. I hope it can defeat the Himalayan blackberry.
This view of the Tacoma Narrows bridge through the thick forest reveals a green landscape perched atop high bluffs overlooking Puget Sound. As far as the eye can see, from this vantage point, the forests were clear-cut to make profits and fuel the economic development of the Pacific Northwest.
But at what cost?
Mima Mounds Natural Area Preserve
It was unbelievably gorgeous weather here in the Pacific Northwest (PNW), with a high of 74 F, so we took a look at a couple of nearby natural areas.
Mima Mounds
This exceptional area isn’t unique but it is an unsolved geological problem. It is also peculiar in being a transition zone between active prairie and forest ecosystems. I’ll try to explain this with photos, and some help from CoPilot, Microsoft’s version of ChatGPT. However, I won’t solve the geological conundrum, which may never be fully explained.
The Mima Mounds are about 16500 years old. They formed as the last continental ice sheet retreated from Washington. The mounds you see in this photo sit atop a gravel surface created at the southern extremity of this glacier. People, including the native Americans who have lived here for tens of thousands of years, have been perplexed by this bizarre topography.
There is a 1.9 mile trail that goes through the area; however, when European Americans first came here, this topography extended for more than twenty miles. Most of it has been demolished.
This is a portion of the information board at the interpretive center. (A) The Mima Mounds were constructed after the ice sheets began to retreat for the last time. The inset map shows the location of the NAP relative to the glacier and modern cities. This was the absolute furthest south of thick ice, but that doesn’t mean it was warm. (B) This is a rare photo of a cross-section through a mound. The dark soil is organic-rich and excellent potting soil. The subjacent glacial outwash is gravel. (C) This is a photo from the air, which shows their regular spacing. This is the geological problem. How could they have formed over about 400 square miles?
There are many theories for the origin of the Mima Mounds, and other mounds found in N. America and elsewhere. These are summarized on the Wikipedia page. I included this photo because it was on the poster; and the size/shape of these blocks of permafrost from Scandinavia are a good match to the mounds we saw. And they are in a similar, post-glacial environment.
Prairie Ecosystem
I’m discussing both the geology and ecology of Mima Mounds together in this post because they are inextricably connected. There are two ecosystems competing for space in this lumpy prairie environment. The result is there for anyone to see, if they ask the right questions.
This low shrub was identified by CoPilot as snowberry, which is a staple of the prairie. I only saw them on the mounds, their roots in good soil, but apparently they also do well in the sandy glacial soil. From my perusal of the internet, I can’t disagree.
My ignorance is hilarious. I thought this was some kind of wildflower … but CoPilot identified it as a Douglas fir seedling. They were growing only on the mounds, sometimes in clusters. This is evidence (to me and CoPilot) that this is a dynamic transitional environment where forest species coexist with prairie flora.
This fern caught my eye because it is not a natural inhabitant of a prairie ecosystem. However, the mounds are near a forest, so … CoPilot thinks it is a bracken fern, which is native to the area but not a prairie environment. It often behaves as an aggressive colonizer in disturbed edge habitats. That last phrase gets my attention because this preserve is at the edge of a mature forest.
This lovely flowering shrub was identified by CoPilot as a species of Lotus, commonly called Spanish Clover, deervetch, or trefoil. It grew in the sandy areas between the mounds. My quick check can neither confirm nor deny this identification, but this common variety of clover is native to the PNW.
This mound is populated by bracken ferns, crowding onto the area with good soil.
I don’t know what species this copse of young trees is, but it is obviously encroaching on the prairie ecosystem.
You never know what you’re going to find when you go outdoors. According to CoPilot, this is probably the result of NAP’s policy of not removing human artifacts that don’t interfere with the environment. Manpower shortages, policy priorities, etc. Mima Mounds was established in 1976, so it’s fair to say that this structure is at least that old. I guess NAP hasn’t gotten around to it yet, which fits my nascent sense of priorities in the PNW.
Bill Frank Jr. Nisqually National Wildlife Refuge
We stopped for a quick visit, which turned into a one-mile death march (for me, after walking 4 miles on uneven ground), to see where the Nisqually River empties into Puget Sound. It originates from the face of an alpine glacier above 6000 feet on Mt. Rainier. This is a tributary stream that forms a series of algae-covered ponds.
Here we are, less than a mile from the Nisqually River’s delta in Puget Sound. There is a lot of downcutting and the creation of sand bars, but no boulders or even cobbles. This glacial river has been tamed by nature over a distance of about eighty miles, but it is still flowing pretty fast. We didn’t make it to the delta … maybe next time.
Summary
This was a great day trip to a fascinating and beautiful area, where the prairie and the forest compete for space on the top of mounds of top soil whose origin is a mystery. This back-and-forth movement of plants on timescales of years to decades suggests that the PNW is alive and well, the flora responding to minute changes in soil and air temperature/moisture, precipitation, wind, etc. Let’s hope these two thriving ecosystems can continue their dance without further human interference.
I have my own hypothesis about the formation of the Mima Mounds, which is consistent with the facts. 1) As the glacier melted and retreated, over thousands of years, shallow lakes developed in local depressions. These lakes were shallow, perhaps twenty feet deep, and limited in extent. 2) Fine-grained sediment (i.e. mud) and organic debris settled in them to depths of no more than ten feet. They were ice covered for part of the year. 3) As the glacier retreated further, streams began to superimpose their beds onto this landscape, but they weren’t like a glacial river (e.g. Nisqually River). These were weak streams flowing over a post-glacial landscape, meandering and not cutting new channels. 4) This mild erosion was superimposed on a landscape dominated (in this area) by an antecedent pattern like that seen in the Arctic (see above photo). Fine-grained sediment was removed, following a suture pattern until only irregular bumps remained. 5) This process of sheet-flow erosion continued to the present day, leaving us with these paradoxical mounds.
I am a sedimentologist, so I think in terms of turbulence and flow as interconnected processes that alter a landscape slowly, one grain of sand at a time. There wasn’t enough turbulence to strip away the veneer of clay over this basin in the time allowed, so it chipped away at the weak edges of lumps of soil that were probably held together by the roots of plants.
In other words, the thawing of permafrost created the pattern, and turbulent flow polished it to what we see today.
Prove me wrong…
Timothy R. Keen 
Recent Comments