Tacoma Chinese Reconciliation Park
I enjoy walking along the shore of Commencement Bay in Tacoma because it is lined with industrial relics, parks, modern shipping facilities, and memorials to my new home’s international connections. But Tacoma, like so many cities, also has a dark past that it acknowledges in many ways. Today’s post is a memorial to one of those darker times.
The memorial park is only a few acres, strung along the narrow stretch of land between the railroad and the sea.
The port of Tacoma’s container handling facilities can be seen in the background, a reminder that life goes on despite the too-often shameful past.
China was suffering from famine and misery in the late nineteenth century. America was seen by some as an escape from poverty and certain death, just as for immigrants from Europe. Immigrating didn’t require visas or approval; if you arrived, you were welcomed, especially the Chinese who took menial jobs to support the industrial development of the Pacific Northwest. They came looking for gold, but settled for whatever they could find. They were welcomed…until economic hard times made them the scapegoats of overall business downturns. Tacoma residents evicted them with extreme prejudice. They sued but were defeated in a court system as racially discriminatory as the people persecuting them. They never received compensation for property or business investments stolen from them.
This is my favorite display because it uses rocks to make its point: the bowed backs of Chinese immigrants are carved in bas relief on blocks of diorite; columnar andesite stands in mute witness to their plight.
This beautiful display has to be seen in parts, but one interpretation is fairly simple: a minor barrier confronts the immigrant, but life abounds behind it, if you can only climb over the low wall…
Beyond the wall is the sea, whose level rises and falls with the tides of history and human events…
A well-constructed bridge will take you over the sea to the promised land…
To a home that is linked to the land you left behind. This pagoda was given to Tacoma by Fuzhou, China–a sister city of Tacoma where many of the immigrants came from. It was built there and transported to this location after the park was authorized by the city in 1993.
I’m not sure what this is about. There was no plaque or explanation anywhere to be found. Tacoma is filled with artwork, but it usually has an explanation. I looked at the park’s web site, but this sculpture wasn’t shown. It faces almost due north…
There was a lot of tropical/Asian vegetation, just as there is throughout the Pacific Northwest. CoPilot thinks the flowered shrub here is Pieris japonica. Japanese. The dwarf conifer is also probably native to Japan. Americans have trouble differentiating different Asian countries, but we also don’t know where Hungary is, or even Switzerland for that matter.
Sights around Lake Washington
It promised to be a beautiful day, so we decided to take a look at Lake Washington, just east of Seattle. This elongate water body was carved by glaciers between 19 and 16 thousand years ago. It was part of Puget Sound until about 5700 years ago, when river sediment isolated it from the sea, allowing it to become fresh water. The original outlet at the southern end wasn’t good enough for early American settlers, so they got approval from Congress to construct a canal with locks to connect Lake Washington to Puget Sound, a drop of 20 feet in elevation. As fans of technological progress, we wanted to see this for ourselves.
The Army Corps of Engineers began construction of a set of locks in 1911, under the supervision of Hiram M. Chittenden. As the sign proclaims, his name remains associated with them; however, they are more commonly known as the Ballard Locks after the city where they were built. The site includes a number of stone-faced buildings and has since come to include a botanical garden.
There are two locks, one for larger, commercial vessels (on the other side of the control building) and a smaller lock. The larger one has two sets of gates to accommodate barges.
Several private boats used the lock while we were there. It takes maybe 15 minutes for the water level to equilibrate whether going upstream or downstream (towards Puget Sound).
The spillway was partially open and the turbulent flow created a very dangerous scene. I wouldn’t want to fall into that water.
Salmon have historically swam into Lake Washington to spawn through the small river (Black River) that drained it before the ship canal was constructed. That outlet is apparently filled with sediment now and the area completely covered with development, including Boeing Aircraft’s main plant, where the Museum of Flight is located. The lock design includes a series of pools called a fish ladder that allows the salmon to get to their spawning areas. I guess they figured out the new route. There’s a viewing room to the right where the fish can be seen making their way up the ladder, but there were no fish on this day; and I forgot to take a picture.
The roof of the fish ladder observation room is decorated with this unlabeled artwork.
Just a short drive from Ballard Locks is Washington Park, which includes an arboretum and Japanese Garden. We took a long walk around the park but didn’t make it to the Garden, which has its own parking area.
The walking paths go out to an island, where State Route 520 crosses Lake Washington, partly using a unique floating bridge construction. Traffic was pretty loud out there. I wouldn’t enjoy having lunch on one of the picnic tables.
These are typical plantings along the paths in the arboretum. I don’t know anything about plants, so I asked CoPilot (giving it the location): the low, flowering shrub is probably Pieris japonica (aka Lily of the Valley shrub); and the tree may be Stewartia.
There were numerous masses of flowering shrubs like this, which is probably a dwarf Rhododendron (according to CoPilot). There were a lot of plants within a group, which didn’t look anything like each other; however, the signs explained that the arboretum had large collections of Rhododendrons and Magnolias, for example.
It was a beautiful spring day, and Lake Washington was the perfect place to spend it. I won’t post a photo of the excellent, home-made hamburger and cold beer I enjoyed at Skillet and Vine after a tiring morning of basking in a warm sun.
Mount St Helens After Forty-Five Years
Introduction
I was a geology student at Arizona State University in May, 1980, when Mount St. Helens made the headlines. It is the largest volcanic eruption in North America, and when one-cubic-mile of mountain collapsed, it became, and remains, the largest landslide in human history. I followed the progress of geological investigation into the eruption with interest as I pursued my education, but progress was slow. It isn’t easy to reconstruct an event that occurred in a few minutes. The area was too dangerous to approach for more than a year because of gas explosions from within the pile of debris, which reached 600 feet in thickness.
Mount St. Helens faded from memory for decades, eventually becoming just another geologic event in a long chain of cataclysms covering billions of years. I never thought about it until I found myself living less than 100 miles from ground zero. I had to check it out. This post is a brief summary of what I found when I visited Mount St. Helens National Volcanic Monument. I hope I can convey some of the excitement I felt at stepping on ground that was literally on fire less than fifty years ago.
Figure 1. I arrived at about 10:30 in the morning and got this image before low clouds settled in, accompanied by fog later in the day. The characteristic volcanic cone is missing; the top of the mountain slants slightly upward to the right in the center of this image. That isn’t a lake in front of St. Helens, just fog collecting in the valley that feeds the Toutle River.
Figure 2. Mount St. Helens is about 2.5 hours from Tacoma. The closest you can drive is Hummocks Trail, but a four-mile hike will take you to the rim of the caldera. Maybe another time.
Older Volcaniclastic Rocks
Figure 3. Mount St. Helens is less than forty-thousand years old, but it is constructed on a thick sequence (~2 miles thick) of volcanic rocks as old as 300-thousand years. Beneath these Pleistocene volcaniclastic rocks mixed rocks of uncertain age that comprise “bed rock” in this area; however, these igneous and sedimentary rocks are much older–spanning the Oligocene epoch (~34-23 Ma). I stopped to look at several road cuts along the new Highway 504 (the original is buried under debris).
A. Exposure of andesite volcanic rocks showing a complex eruption history, which includes ash layers and what looks like tuff (ash so hot it melted together to form a glass-like volcanic rock).
B. Close-up from the left side of (A) showing a layer of volcanic breccia that is now vertical. Individual clasts are visible but there is very little matrix. The dashed line indicates the approximate bedding plane of the layer. The rounded block labeled with ?? is about 12 feet in diameter. This is a puzzling structure. My guess is that there was a collapse of one or more volcaniclastic layers into a ravine after deposition. A jumble of material.
C. Photo of a complicated structure separating the left side of the exposure (tilted beds and blocks) from the right side (horizontal ash layers). The dash line is meant as a reference to the vertical beds in (B), but it was difficult to determine orientation. However, a clear change in texture suggests a depression, which may have been a conduit for volcanic material to erupt. The BLOCK/PLUG label reflects this interpretation. Within this “BLOCK” there is a discrete region of thin, irregular bedding that I’ve labeled (for convenience) as a CHANNEL? The question mark reflects my doubts about this identifier. Nevertheless, this road cut exposes a sequence of events: lava and ash being erupted onto an irregular volcanic landscape; probable surface erosion for some period of time; physical disruption and collapse, probably while still hot, of some part of later volcanic material. I don’t have enough experience with volcaniclastic sediments to say anymore than that.
D. The pushpin shows the location of this road cut. The blue ribbon is Coldwater Lake, where Hummocks Trail is located (see Fig. 2); this exposure is more than ten miles from the caldera, and hundreds of feet above the valley floor.
Figure 4. This post-eruption road cut is a mile or more further from the caldera. The solid line was a striking lineation that could be a fracture or possibly a contact between eruption beds. The dash-dot lines are apparent bedding planes between andesite flows. There is no ash present at this location. The dash lines delineate what I’m calling a BRECCIA because there is no evidence of bedding and the overall appearance is irregular; also, some large blocks were evident, although they could be a result of differential weathering. Lava flows are notoriously difficult to trace any distance laterally. Nevertheless, this exposure is similar in appearance to Fig. 3 with respect to the discontinuity between identifiable volcaniclastic deposits.
Figure 5. This road cut is located (see inset map) in an area the geologic map (Rock D) identifies as volcaniclastic rocks of Oligocene age (33.9-23.04 Ma). This is a smaller exposure than seen in Figs. 3 and 4, but it is also very different in appearance. That could be an optical illusion; close examination of the photo (I took it from my vehicle stopped in the middle of the road) suggests to me that this is ash that was so hot it formed what is called a welded tuff when it fell, after being blown into the atmosphere by an eruption. The light color suggests a magmatic composition more like granite than gabbro, or even diorite. That wouldn’t be surprising in the complex magmatic environment of a subduction zone, where partially melted, oceanic crust (e.g. gabbro and basalt) chemically mixes with continental crust (e.g. granite and diorite).
This completes my survey of older volcanic rocks near Mount St. Helens. There are no rocks exposed that explain the apparent hiatus in volcanism between about 23 and 2 million years ago. That is a story for another day…
Volcaniclastic Deposits from May 1980 Eruption
Figure 6. Photo A was taken a few days before the eruption in May, 1980. Image B was taken a few days afterward. The pre-eruption volcano was 9677 feet tall, but the obliterated peak is only 8365 feet. The total volume of material displaced exceeded one cubic mile, most of which was rock that collapsed during the rock slide preceding the actual eruption. The flat area fronting the volcano in (B) is a large fraction of the previous peak, which filled in several channels originating at the volcano. Note the holes in (B), which are probably blow-outs of gases trapped in the debris.
Figure 7. (A) This plaque was located along Hummocks Trail. I’ve supplemented it with the map of volcaniclastic deposits shown in (B). I will focus on the three major volcaniclastic deposits I encountered at Hummocks Trail (blue circle in B), which are numbered 1-3 in both figures.
The first stage was collapse of the north flank of Mount St. Helens (brown in A and cross-hatched in B). This was a run-of-the-mill massive landslide that followed existing drainage, until stage two occurred.
When the rock containing the highly pressurized magma was removed. The resulting release of pressure created an explosion equivalent to 10-50 megatons of TNT; although a volcanic eruption is not analogous to a nuclear explosion, the energy released was roughly 1600 times the energy of the Hiroshima atomic bomb. It moved a lot of rock. This blast occurred seconds after stage 1 began; the hot gases overtook the rock slide, driving rock and debris up the sides of the valley, removing everything, including top soil, within a few miles of the volcano. The orange area in B shows how widespread this explosion was.
Stage 3 was a pyroclastic flow (red in B), which was limited to the immediate vicinity of the caldera; however, what goes up must come down, so several inches of ash were deposited as far as Spokane, Washington–400 miles distant.
Video 1. This video shows debris from the landslide (Stage 1) that was pushed at least 300 feet from the original valley floor to the ridge by the unimaginable blast of Stage 2. The main slide followed Toutle River (North Fork), but with this impetus, debris was launched over the canyon walls. That’s what this video shows. It’s like the heavy stuff collected at the top of the ridge whereas the sand/gravel-sized debris was blown miles further.
Figure 8. This photo is looking south towards Mount St. Helens from Hummocks Trail (see Figs. 2 and 7B for location) along the Toutle River (North Fork), which is more than a hundred feet lower, even after being filled with debris from the 1980 eruption. Note the difference between this scene and the deposit from Video 1. It’s difficult to comprehend the dynamics of a blast (Stage 2) capable of pushing rock (Stage 1) up this slope; when the explosion lost energy it simply dumped its load, creating a surreal landscape. The debris has very little clay and is thus non cohesive; thus slumps like this are common. Note the small hill and “ridge” in the middle of the photo. This terrain makes no sense, other than erosion has been etching it for 40 years.
Figure 9. This layer of ash I encountered along the Hummocks Trail is a remnant of a vast sheet originally deposited during Stages 2/3–breaking such a continuous eruption sequence into stages is useful but not particularly elucidating. It all happened too fast to comprehend. You might call this an “over-bank” deposit, like when a river tops its natural levee and deposits fine-grained sediment on its floodplain.
Figure 10. Hummocks Trail followed a small stream through a bizarre landscape comprising multiple small ponds like this one. A dam constructed of eruption debris (left-to-right in the center of the photo) has blocked the stream flow, creating a meandering channel during low-water conditions; but I can imagine all those dormant grasses erupting later this spring. I encountered several of these marshes, each one defined by water trying to find a way out of this labyrinth. According to Fig. 2, this is the outflow from Coldwater lake; the eruption partially blocked its path but nature is finding a way through this discombobulated landscape.
Figure 11. This photo perfectly captures the topography of Hummocks Trail. This is the northern end of the trail, which is a little higher; the Toutle River (North Fork) is more distant and the cliffs we saw in Fig. 8 have receded, replaced by moderate slope; however, note the fine-scale nature of the hummocks here. They are ubiquitous but contain only a few scattered boulders.
Figure 12. This is a view of Coldwater Lake from the visitor center, looking south towards Mount St. Helens. There are two things to note from this image: 1) the Toutle River valley is a broad, flat plain because it was filled with debris from Stage1; 2) the overflow deposits (e.g. Video 1) have blocked the lake and raised its level. The source of water we saw in Fig. 10 is evident in the center of the photo. This isn’t a sedimentary dam, created by flood deposits, or even a glacial dam produced from the debris scraped up by thick ice sheets. The shoreline was modified when Mount St. Helens collapsed and then exploded with unbelievable violence.
Final Thoughts
The eruption of Mount St. Helens in 1980 gave geologists a rare opportunity to see how Earth produces sausage. Let me explain my metaphor.
Ocean crust is denser than continental crust it encounters at a convergent plate boundary, and at a lower elevation. It is thus overridden by the continent, forcing it to dive into denser and hotter rocks at depths of hundreds of miles. This obviously displaces hot and ductile rocks, heating the subducting rocks even more; the sausage-making operation has begun. Still pushed from behind by the conveyor belt of oceanic crust being subducted, this basalt/gabbro mixture heats enough to boil off the water contained in its sedimentary cover as well as any constituents with a reduced melting point (e.g. silicon-rich minerals). This superheated material rises through tens-to-hundreds of miles of crust, heating it and producing a mixture of oceanic and continental crust.
Plate tectonics keeps turning the crank on the sausage machine for tens (even hundreds) of millions of years. The molten mass of magma keeps rising because it is less dense than the rocks through which it is passing, until the pressure has decreased enough for it to find cracks in the solid crust. The magma fills these cracks, which often lead to fissures in the surface; the magma erupts. The magma cools and begins to solidify, forming a pluton at depths of several miles to tens of miles.
This process keeps operating, in fits and starts, until the tectonic plates change direction. In the meantime, the upper crust has been filled with multiple plutons (solidified magma chambers), sometimes squeezed into the volcanic rocks from previous eruptions. Individual magma chambers/plutons are about one mile in diameter, although they take many shapes, and remain active for less than one-hundred-thousand years (often much less). These are injections of fluid rising through weak points in the crust, driven by pressure paths–not missiles launched from the mantle. They are like the sweat on your brow after a hard workout.
Mount St. Helens has released a lot of pressure, although it is still very dangerous at human scales. Chances are that this magma chamber will solidify within the next hundred-thousand years; but the unstoppable sausage machine will continue cranking out more mixed material in a molten form until it has filled every nook and cranny in the upper crust. That’s how mountain ranges like the Sierra Nevada were formed. It takes a really long time.
Mount St Helens probably won’t erupt again at the scale of the 1980 event, but that doesn’t mean much if you happen to be camping near the caldera when a smaller eruption occurs. After all, the magma chamber is still extruding lava in an unsteady process that is currently pretty slow. However, we humans can’t see fractures in bed rock; thus, the next and the next, etc, magma chamber could appear anywhere from Northern California to British Columbia. There are plenty of young volcanoes in the Cascades that haven’t blown their tops yet.
Who’s next?
Ecosystem Notes from Quinault Rainforest
Introduction
I’ve spent the past few months wandering the Olympic Peninsula with my attention fixed mostly on rocks—tilted beds, breccias, sea stacks, and the stories they tell about deep time. But along the way I’ve been noticing the living world with the same quiet fascination. I’m not a biologist and I don’t pretend to be; I can’t name any of the plants I pass. What I can see is how each organism plays a role in the larger system, the way geology shapes life and life responds in turn. These are simply notes from a wanderer paying closer attention.
I’ll try to remember to label these environmental posts as NOTES to avoid any confusion, especially on my part. This first post arises from a short walk on a semi-muddy trail through the Quinault Rainforest, on the Olympic Peninsula. I won’t have much to say about the photos, and all identification will come from CoPilot (aka ChatGPT). I’m certain its identifications will be better than mine after hours of searching the internet.
Quinault Rainforest in Olympic National Park
Plate 1. That raging stream about 50 feet below me is one of hundreds draining this temperate rainforest, which gets about 12 feet of rain per year. Note the ferns, which are everywhere, even in the temperate forests of northern Virginia. Ferns must be the most common plant in cooler forests. I am in a narrow strand of Olympic National Park that has never been logged. This is primordial nature, viewed by a geologist, but I’ll do my best.
Plate 2. Map of the Olympic Peninsula showing the areas I reported on in previous posts. I’m going to be focusing on Site A today, with a few photos from D.
Plate 3. I haven’t seen this anywhere else I’ve lived, not even northern Virginia, but they occur everywhere here in Washington. Apparently this is a common occurrence in rainforests, where the ground is a dangerous place for seeds. I couldn’t identify the species in this photo, but this practice is very common for hemlock.
Plate 4. This pile of debris is a large log turning into compost and supplying nutrients to a variety of plants. The top of the photo shows the base of a young tree growing out of all this chaos. According to CoPilot and the Olympic National Park map, this area has never been logged, so I am in wonder of this pile of “forest garbage”. Is that sandy soil I see? Where did it come from? I don’t know.
Plate 5. If you look close in the exact center of this photo, you’ll see daylight on the other side of the base of this unidentified tree. It’s about six-feet in diameter and covered with an epiphyte community of mosses and liverworts. Those aren’t leaves or fronds, but communities that mimic ferns–for their own reasons.
Plate 6. Here’s an example of a Western Red Cedar that has grown into a mature tree after being nursed by a stump. I guess it will eventually absorb the rotting stump and grow to full height, but this is the largest I’ve seen so far in the region.
Plate 6. This miniature ecosystem caught my eye, but I had to turn to CoPilot to get an idea of what’s going on. As a tree trunk decays it goes through five stages: 1) moss; 2) liverworts; 3) fungi; 4) shrubs; and 5) young trees. This one seems to be in stages 1-4. I didn’t see any seedlings on it. The shrub is probably huckleberry and the mushrooms a bracket fungus, probably Trametes or Stereum.
Plate 7. I am fascinated by these nurse trees after seeing species of fig trees in Australia that devour living trees, like a giant fungus or alien. These are nursing on dead trees, however, so it isn’t as gross; but this one is now standing on its own legs after the original stump has begun to collapse.
Plate 8. This is the largest Spruce tree in the world. It’s 191 feet tall and about 1000 years old. It is growing in a swampy wet land at the inflowing stream to a glacial lake, Lake Quinault.
Plate 9. I thought this was toxic waste until CoPilot took a look at the photo: this is a mass of frog eggs (probably northern red-legged frog). There were several more at the shallow, marshy wetland where a stream fed Lake Quinault. The water is so clear you can see the bottom, which is only a couple of feet down.
Kalaloch Beach in Olympic National Park
Plate 10. This one was a doozy. These objects are one-two inches long, thin, translucent, and oval in general shape. At first, CoPilot suggested insect wings (until I told it the size), then gull secondary feathers (until I said, “no way”), then settled on small fish cranial bones–e.g. the opercula, the bone that covers the gill. I asked for references, but it supplied me with titles and no links (how did it find them?). I spent longer on this photo than I wanted to. I don’t fault CoPilot for its ambiguous response because I found nothing when I looked very specifically. This phenomenon is either so common that no one bothers mentioning it, or infrequently observed that no serious beachcombers have stumbled across it. I’m going to have to agree (for now) with CoPilot that these are small bones from a school of fish that was decimated by either predation, coastal fishing, or disease and only these translucent cranial bones survived by floating, until waves concentrated them on this beach. This is the only beach where I saw them. I guess there are no easy answers to some questions–unless someone who reads this is a marine biologist.
Plate 11. I solved the mystery of the white objects on the beach (Plate 10). I spoke to an ecologist I know who suggested they are a Hydrozoa called Velella-velella, which floats on the ocean like a jellyfish. They are a colonial organism that is blown about by the wind. They don’t swim so they are easily blown onto a beach and carried by waves. (Here’s a good article about them.)
Cape Flattery
I reported on this amazing location in a previous post. You can scan that post to get an idea of where these photos were taken.
Plate 11. I don’t know if this living (it looked healthy to me) tree was stressed or not, but CoPilot thinks these are perennial bracket fungi, which favor environmentally stressed conifers. There were only a few on this tree. I noticed that this forest didn’t show nearly as many signs of decay as Quinault Rainforest, despite its exposed location.
Plate 12. I had to throw this photo in because the root growing out of the tree(s) on the left looks like a dog that got its head caught in a hole, and died there. Its limbs of limp. Overactive imagination, I know. Nevertheless, this is a bizarre image because the dog is lying on top of a mound of soil. I’d bet there was a stump there that has decayed because the trees visible in this image are both composed of multiple trunks. A large tree died here (like the dog) and these are its adopted offspring. I would add that Cape Flatters, which is part of the Makah Reservation, has never been commercially logged. This is old-growth forest and this is a naturally occurring phenomenon.
Summary
Moisture drives everything on the Olympic Peninsula, soaking old volcanic and sedimentary foundations until the forest grows straight out of its own decay. Fallen logs become elevated nurseries, their wood breaking down under fungi and mosses until they’re more sponge than tree. Hemlock, cedar, and huckleberry take root on these platforms, sending roots around stumps and into the thin soils draped over ancient bedrock. Even the beaches tell the same story: waves sorting bones, shells, and driftwood carved from headlands shaped by tectonics and storms. It’s an ecosystem built on slow collapse and constant renewal.
Acknowledgment
I am experimenting with using CoPilot (aka ChatGPT) to help as I pursue my growing interest in ecosystems. I have been up front about where it contributed. It has been a great help, as well as an inspiration; if not for CoPilot, I wouldn’t have had the time of inclination to add these ecosystem NOTES to Rocks and (no) Roads. In fact, I’m tired of this entire series of posts, for which I get no compensation other than sharing my observations of the world. As a final note, CoPilot wrote the Summary and I stand by it.
Now I have to think about more than just rocks…
Cape Flattery: Conglomerates at the End of the World
Figure 1. I ran out of road and land, ending up at Cape Flattery on the Makah Reservation. This is Location D in Fig. 2. A half-mile hike down a boardwalk took me to the end of the world, where the cliffs are about 80 feet above sea level. This photo is looking northward towards Vancouver Island, Canada, in the distance. Wave action has cut a wave terrace, a seen in the center of the image, and a series of sea caves.
Figure 2. Today’s post takes us to Site D, which is shown in a geologic map from Rock D in the inset map. The rocks are a mixture of sandstone and conglomerate of Eocene age (56-34 Ma). This is the same time that the lower Cascades were being created east of Puget Sound. Note the large number of faults (thin lines) shown in the inset map. Many of these are strike-slip faults with motion of the opposing crustal block to the left, which would explain why the sedimentary layers in seen in Fig. 1 are almost horizontal, dipping slightly towards the sea.
Figure 3. The sea stacks seen further south have been replaced with rocky islands like Tatoosh Island, which has a light house. Pacific Ocean seafloor (Juan de Fuca tectonic plate) is being actively subducted along the Washington-Oregon coast at about 2 inches/year, but the plate tectonic geometry is complex in this area. This could partly explain the large number of faults seen in Fig. 2 as well as the high elevation of bedrock. Maybe.
Figure 4. This photo was taken looking down towards the wave-terrace on the south side of the lookout point. For scale, the largest boulders are a couple of feet long, based on exposures at the surface of the trail. This is a textbook tectonic breccia. However, note that most of the rock fragments are rounded, so they have been transported some distance before reaching their final resting place. Some of the layers are relatively uniform with a few large boulders whereas others resemble the cobblestones we saw at Ruby Beach. Each bed might represent a single depositional event (like a landslide) or accumulation over years. These are marine rocks, deposited on a submarine fan, probably as turbidity flows. The process that created them is occurring now a few miles offshore, where the rocky outcrops we saw are eroding and supplying large and small fragments to a steep continental shelf.
Figure 5. This image looks like run-of-the-mill gravel like you see on pathways and drives, but it is Eocene rock, and I mean solid rock (Note the large, gray piece protruding from the cliff in Fig. 4). This angular slab is about a foot in length. There is no Pleistocene glacial till in this area, even if the ground looks the same. This is a picture frozen in time, where an angular piece of what looks like sandstone, but could be andesite, slid downslope along with smaller fragments.
Summary.
This is the last of my geology posts from a weekend excursion along a hundred-mile stretch of the Washington coast. This is a high wave-energy coast with a tidal range of about 10 feet, the beaches covered with sand and cobbles. Sea stacks protrude from the beach, culminating in cliffs made of 50 Ma conglomerates. Beneath our feet, ocean crust was being subducted at several inches per year, feeding a system of magma chambers that are actively venting through volcanoes like Mt. Saint Helens, Rainier, and Mt. Baker. Rainfall drops along this coast at up to 12 feet per year, feeding streams that carry immense quantities of sediment into the trench created by the subducting ocean crust.
Geology doesn’t get any realer than this…
Tectonic Breccia at Ruby Beach
Figure 1. Ruby Beach is located about 10 miles north of Kalaloch Beach (Point C in Fig. 2), but the coastal morphology has changed substantially. This photo was taken at sunrise during low tide, exposing many outcrops of basement rock, which is the same unnamed sandy rock formation we saw before, but its composition has changed.
Figure 2. Today’s post describes the coastal geology at Site C. I’ve already discussed the Quinault Rainforest and Kalaloch Beach. I will focus on what is different from the previous post. The inset geologic map from Rock D will be referred to below.
Figure 3. Basement rock of general Tertiary age (66.5-2.4 Ma) is more exposed here although it is overlain by Pleistocene glacial sediments. This photo shows a rocky island that can be reached at low tide, and a promontory. The beach is composed of rounded cobbles in a matrix of sand, silt, and some clay. The finer sediments are restricted to the lower swash zone (Fig. 1).
Figure 4. This is a sea stack, a standalone rock pillar. The beach is a thin veneer spread across a rocky basement that is more irregular than we saw at Kalaloch Beach, where the outcrops resembled a wave-cut platform more than we see here. The first thing that occurs to me is that this area hasn’t been exposed to the erosive power of waves for as long an interval. Maybe. Let’s take a look at the inset map of Fig. 2. The black lines represent geologic faults, where rocks have been displaced by tectonic activity. Note that the stretch of coast we’re concerned with is bounded by faults perpendicular to the coast. Furthermore, there is another fault separating Sites B and C. I should take a moment to point out the relationship between faults and river valleys: faults create weak zones within the crust, which are exploited by erosional forces like water and glaciers. Thus we see valleys at both B and C; however, the intervening fault is part of a complex fault system that appears to have led to less surface erosion. Faults cannot be directly dated, only indirectly by the age of the rocks they displace, and in this case those rocks are themselves difficult to date. Thus, it is possible that vertical movement, even a few hundred yards, could have made this beach more irregular than Kalaloch Beach only a few miles to the south–on the other side of a fault. Plausible, but don’t bet your retirement on my hypothesis.
Figure 5. Back to the rocks. This photo puzzled me because I’m not an experienced field geologist, despite my regular posts; however, CoPilot came to the only plausible conclusion: the primary material here is a breccia/graywacke; the smoother material is calcite filling fractures that occurred during faulting (see Fig. 2 inset). We must ALWAYS remember that a sedimentary rock’s history isn’t confined to deposition; a lot happens during burial to many miles and subsequent exhumation and deformation.
Figure 6. This photo shows a typical graywacke texture with layering, as you might expect with episodic deposition of event beds (e.g. turbidites on a submarine fan); but the upper part of the image is similar to Fig. 6. I asked CoPilot about the source of so much Calcium and I agree with its answer: Some of the Calcium came from marine invertebrates living in the area, but the bulk arrived later, when the sediments were buried deep (several miles) within the accretionary wedge where Calcium is released from minerals like feldspar. It’s really hot down there and the pressure is INTENSE.
Summary.
Not only was Ruby Beach a beautiful area on a cool winter/spring morning, it gave us more insight into the complex life of the earth’s crust. These rocks were probably deposited as poorly sorted graywacke on a steep continental margin overwhelmed by sediment eroded from the rising Cascades (more than likely the Eocene, 56-34 Ma). They were buried for a few million years, before being scraped off the subducting oceanic crust and filled with hot fluids that originated from deeper within the accretionary prism. They were never so humiliated that they became melanges but it was a pretty rough ride, even for a rock.
To put this all in perspective, dinosaurs had just gone extinct (~65 Ma) when all hell broke loose and the Cascades Subduction Zone became very active about ten-million years later; the earth became hot as hell, mammals and birds were beginning to get their legs and wings. While the ecosystem changed dramatically, these rocks were being ground up and spit out by the earth because they were stuck on the end of its tongue. We hominids didn’t come along until these rocks were exposed to the vagaries of the weather and had eroded for a VERY long time.
Try not to laugh at the punch line: Our entire history is contained in the Pleistocene glacial sediments overlying these fairly young sediments.
It boggles the mind…
Coastal Geology of Kalaloch Beach
This report is the geology supplement to my general post about the Olympic Peninsula. It focuses on the geology of the beaches because, to be honest, Quinault Rainforest was impenetrable, physically and geologically, without massive logistical planning and support. What I found was more than I expected.
Figure 1. Photo looking north along Beach 4 at Site B in Fig. 2. The tidal range is about 10 feet here and the primary sediment consists of sand with a substantial mud component. The rocks seen in this image are bedrock that protrudes above the veneer of beach sediment. The cliffs to the right comprise glacial till that is less than 2.4 my old (Ma hereafter) deposited by glaciers during the Quaternary geological period. This photo was taken near low tide. The dark color of the beach surface is caused by the relatively large clay component (i.e. mud).
Figure 2. Location map of today’s field area, which will focus on Site B.
Figure 3. Schematic of the Cascadia Subduction Zone as it appears today. The Coast Range, which includes the Olympic Mountains, consists of sediments and volcanics that have been scraped off the subducting ocean crust. The white arrows at the front of the image don’t reflect the actual geometry of these sedimentary rocks. We’ll get to that in a minute. Today’s post will focus on these sediments and discuss their original depositional environment during the Tertiary period (~65.5-2.4 Ma), as well as evidence for structural deformation.
Figure 4. This photo has been marked-up to highlight what might not be obvious to a non-geologist. First, older sedimentary rocks have been tilted to a high angle (dark blue bedding plane line) by faulting, as suggested in Fig. 3, and exposed to erosion at the surface. This erosional surface is shown by the yellow line. These Tertiary sediments were buried several miles beneath the ocean surface where the grains were cemented by heat and pressure. We don’t know exactly when this occurred or how long this process took, but they were later overlain by younger glacial sediments during the Pleistocene epoch (2.4 Ma to present). The age of sedimentary rocks can’t be pinned down unless they contain material datable by radiometric methods or, more qualitatively, by the fossils they contain. Sandy sediments don’t contain fossils very often and I didn’t find any radiometric ages in either Rock D or the USGS geologic map, so I guess the Tertiary date is the best we can do for now.
Figure 5. Close-up photo of the contact between the Tertiary rocks and the glacial till. Note that the cobbles aren’t falling out of the fine matrix sand and clay; this is because these young (>2.4 Ma) conglomerates have been partially cemented and, in fact, they were stuck to the older rocks below. This photo tells us a lot: 1) the older rocks were tilted at depth (maybe a mile or more) and then pushed upward as suggested in Fig. 3 until they were exposed to the atmosphere; 2) in a very short time they were covered by cobbles (~2 inches or less) that had already been rounded in a river, which takes several miles of transport; 3) the type of sediment varied rapidly, from coarse sand to cobbles, probably within decades if not years, due in part to periodic changes in surface drainage (e.g. the advance and retreat of glaciers); 4) this is a good example of the principle of Uniformitarianism–the present is the key to the past: we see similar processes occurring today along the many streams and rivers draining the Olympic Mountains. But what about those pesky Tertiary sandstones?
Figure 6. This photo of the Tertiary sedimentary rocks reveals packets of thin-bedded fine sandstone with intercalated dark layers of (presumably) mud. I didn’t see any cross-bedding, which would indicate deposition in a river or nearshore dominated by waves or currents. What is obvious that this ancient (~50-2 Ma) shoreline was receiving sediment from a distant source, probably the volcanic highlands of the modern Cascades (see Fig. 3). Let’s take a closer look at one of those wavy layers.
Figure 7. Close-up image of a thin layer (about 3 inches), showing what is called Flasier bedding. This is found in modern environments where high-energy (e.g. waves and tides) periods are interrupted by quiet times during which fine sediment can be deposited between ripples. It is indicative of a shallow marine environment.
Figure 8. These holes were evident throughout the exposure. They are problematic and probably originated in several ways; however, one plausible explanation is that soft-bodied animals like worms burrowed in the sediments and their burrows filled with sediment with a different composition (e.g. fecal pellets). These channels then preferentially eroded when subjected to the harsh nearshore environment in which they are found. The presence of such holes at the unconformity (see Fig. 5) proves that they predate deposition of the overlying glacial till. Unfortunately, such trace fossils don’t tell us anything about geologic age, only that this seashore was teeming with life.
Figure 9. I stopped at another accessible beach a couple of miles south, but still indicated as Site B in Fig. 2, where the rocks were sandstone but with very little clay. The beds seen in this photo were thick (1-3 feet). They were not deposited in a high-energy, environment like those we saw before; they were probably deposited on the shoreface below fair-weather wave base–possibly part of a nearshore bar or barrier island. After deposition and burial, they were tilted less steeply than those seen further north (Fig. 6). The unconformity is seen in the upper part of this image, but it doesn’t seem to have as many rounded cobbles as before (Fig. 5). I have no way of knowing the relative age of these two exposures; this Tertiary rock unit is approximately 3000 feet thick and represents millions of years. All we can say for certain is that this shoreline wasn’t that different from what we observe today. Uniformitarianism in action.
Figure 10. This exposed outcrop within the tidal zone reveals what are probably concretions of iron oxides, formed during early diagenesis. They superficially resemble fossils, but that is not the case. As the sediment was squeezed during burial, incompatible elements like iron formed irregular blobs in an otherwise uniform quartz sand matrix.
Summary
This coastline was part of the Cascadia subduction zone during most of the Tertiary period. Sediment, including a lot of sand, was eroded from rocks being uplifted further inland where volcanism was active, especially during the Eocene (55-35 Ma). Beaches like those we see toady were common, as well as the various depositional environments found along the Olympic peninsula, including fluvial and submarine fans, beaches, and cliffs. But no glacial sediment.
These sediments were buried as more material was removed from the rising orogenic belt, which included granitic rocks with lots of quartz. Eventually they were caught by the complex trench uplift (see Fig. 3) and scraped onto the edge of N. America. This involved faulting primarily, suggesting this was a fairly shallow process (folds occur at depth where rocks are ductile). The tilted rocks were eroded for millions of years; then, about 2.4 Ma glaciers (nothing to do with subduction) covered the region and deposited all kind of sediment: rivers, lakes, undifferentiated till, moraines, etc.
Just as the East Coast of America has been a passive margin for more than 200 my, the West Coast has been a convergent margin. Instead of being steadily worn away by wind and water, these rocks are rising out of the sea at about 2 inches per year. And what a ride it is…
The Olympic Peninsula: Quinault Rainforest to Cape Flattery
This is the first in what I hope will become a regular series of blogs from my travels around the Pacific Northwest (PNW) as well as trips throughout the world. This series accompanies my main blog, Rocks and (no) Roads, which reports on the geology of various places to which I travel. You could see I’m expanding my horizons; in addition to posting about general sights in this post, I will also be including environmental and ecological observations that are of interest to me. My background is in geology, but I’ve become aware of a lot more since moving to the PNW. So this is a learning experience, thanks in large part to the availability of expert assistance from CoPilot, Microsoft’s version of ChatGPT. I’ll be turning to it to identify plants and evidence of animal activity in future posts.
This is the base map I’ll be using in many of my posts from the PNW. The star indicates my base in Tacoma. Today’s post describes a two-day trip to circumnavigate the Olympic Peninsula. Although this area is the wettest in the contiguous United States, with annual rainfall up to twelve-feet, it was clear for the duration of my visit. The labeled areas indicate where the photos described below were taken.
Location A: Quinault Rainforest. Photographs can’t do justice to the experience of being surrounded by a temperate rainforest. There are many trails of different lengths, but I followed a shorter one (about one mile) that followed Willaby Creek for a while before turning into the depths of the forest. This image shows the creek rushing by about 50 feet below the trail as it races to the south shore of Lake Quinault.
Location A: Quinault Rainforest. This rotted log is about six-feet in diameter. It is representative of the ongoing decay and rebirth of the forest. I’ll talk more about that in another post. Note the ferns growing out of the decaying wood.
Location A: Quinault Rainforest. There are at least half-a-dozen species of giant evergreen trees in the rainforest, and I can’t identify any of them; but CoPilot suggests it might be a Coast Redwood, part of a local population found in this area. This example is typical in an area known for its “Champion Trees”. We’ll get to that in the next photo.
Location A. Quinault Rainforest. This is the world’s largest Spruce tree. It is 191 feet tall and about 1000 years old. It is one of the six champion trees located in Quinault Valley. The other champion trees are: the world’s largest Western Red Cedar, Douglas Fir, and Mountain Hemlock; and the largest Yellow Cedar and Western Hemlock in the U.S. This tree is growing in a wetland area at the NE end of Lake Quinault.
Halfway between Sites A and B. During my day-trips around the area, I’ve noticed a what appears to be a regional interest in post-industrial art, including but not limited to large concrete facilities that have been left to decay in place, as well as small sculptures and other curiosities scattered throughout the cities and forests. I don’t know if this is intentional or not: the roof of the information board collapsed (no doubt because of 12 feet of rain per year) and was set aside, possibly as a monument to nature?–or evidence of the poor funding and mismanagement of the National Park Service.
Location B: Kalaloch Lodge. This is the view from the deck of the lodge where I spent the night. Kalaloch Creek meanders as it approaches the coast and enters the Pacific Ocean here. An impenetrable pile of driftwood (actually logs and entire trees) has collected on a sand spit deposited on bedrock.
Location B: Beach 4 at Kalaloch. Steep bluffs of glacial till front a wide beach with many exposures of rock, which I’ll discuss in my next post.
Location C: Ruby Beach. This was the last beach before US 101 turned inland for ten miles. I took a video because a series of photos can’t possibly convey the beauty of this location as the sun was rising. Note all the rocks protruding from the water at low tide. The rocks are rising from the earth as we make our way north.
Location C. This selfie demonstrates how chilly it was, with the temperature below 40F. Rock formations like this are called stacks; they are erosional outliers as the coast recedes over millions of years, pounded day and night by rocks carried by waves; and tides that exceed nine feet–twice a day! You have to time your visit accordingly or all you’ll see is water.
Location D: Point Flattery. This is the extreme tip of the contiguous United States. The bedrock we saw further south, at Ruby Beach, now forms wave-cut cliffs that tower 40-80 feet above the waves. The top of the bluffs is 330 feet above sea level. The view from the catwalks is breathtaking. Vancouver Island, BC, is visible in the background, with peaks around 6000 feet.
More PNW Humor. All of the toilets we saw along the coast were constructed over septic tanks, with warnings about what to put in them. Someone with a sense of humor modified just one word of the official message…
If you get the chance, I strongly recommend visiting Olympic National Park, but you’re going to want to spend a week unless you live nearby in the PNW.
Gravel Beaches on Vashon Island
This photo of the gravel/mud beach at Fern Cove Nature Preserve reveals a marine delta, fed by Shinglemill Creek. Unlike the mud/sand delta we saw at Dash Point, the sediment here is dominated by rounded gravel and small boulders. Mud, sand and silt form the matrix. All of this material is available from the glacial till that comprises Vashon Island.
The inset map (right) shows the two sites I visited today. Fern Cove is located near the northern tip of Vashon Island whereas Maury Island Marine Park occupies the SE side of an island that is connected to Vashon by a fill zone about 200 yards across (which is eroding away as I type).
Fern Cove Nature Preserve
Vashon Island was logged out, so the beautiful evergreen forests that cover most of the island are all second growth. The state is trying to restore the original habitat, and Fern Cove is a good example; they don’t allow dogs!
I’ve noticed that people in the Pacific Northwest (PNW) appreciate industrial art of a practical nature. I found an example here, in a threatened habitat that is actively being restored. I guess this old truck body isn’t hurting anything; I’ve also noticed that communities in the PNW don’t waste money on unnecessary actions.
This photo shows how the gravel is localized within the delta, forming low nearshore gravel bars. The intervening areas are muddier than I found at Dash Point.
These gravel bars do more than concentrate larger rock fragments. Acorn barnacles encrust the larger ones, which are several inches in diameter. The tidal range is about 7 feet here and the beach is inundated twice daily, so I think these are living. I’ve seen barnacles on large boulders before, but I didn’t know they grew on stones. I guess the wave energy isn’t high enough to disturb them over a life cycle; their larvae must hang around after a storm and find a new rock to inhabit.
On all the beaches I’ve reported on for Rocks and (no) Roads, I’ve never seen this before. This is an active feeding area for sea birds. These are mussels, which the birds grab from a nearby mussel colony on the shallow delta front and drop on exposed gravel during low tide. The shells break open and the birds feast, leaving their dirty dishes behind.
This Western skunk cabbage is just emerging from the wetland surrounding Shinglemill Creek. It will grow leaves up to two feet long, but it makes a beautiful display in the unseasonably warm late winter we’re having in the PNW.
Maury Island Marine Park
On the opposite side of Vashon Island, I visited a gravel quarry that operated for about seventy five years, before being purchased by the state as a park. This is another example of letting nature recover without interference.
This photo looks SSE towards Dash Point. Commencement Bay and Tacoma are visible in the background; a little sunlight is shining on the bay. The cliff has been quarried for 75 years, so the 400-foot vertical face is now a steep incline with a trail that utilizes many switchbacks to reach the shoreline. Let’s see what I found…
There is no mud or sand visible on this beach. I thought that might be a side-effect of so much gravel quarrying, so I walked beyond the limit of the quarry; the substrate didn’t change, but there must be lingering effects after so many decades of preferential sand removal.
After what I saw at Fern Cove, I thought I was prepared for whatever I might find; but I never expected to see clam shells with the hinge lineament intact; this shell even closed after the bird (e.g. gull or crow) has eaten the soft tissue. The shell actually snapped shut after the animal was eaten. Amazing!
This spectacle gives driftwood a whole new meaning. Someone even built a crude shelter in the background from the logs that have collected over the years. There are a lot of trees in the PNW and many of them fall into Puget Sound, ending up all over the place. This looks like what coastal geologists might call a “hot spot”, a location where waves converge during storms.
After a hot climb, even in 45F temperatures, I made it back to the top of the cliff. This area was a barren wasteland in 1975, when the state took over; park authorities and volunteers have worked tirelessly to not only allow recovery, but to keep out invasive species. I think they’re doing a pretty good job.
Summary and Acknowledgments
I learned more biology on this day trip than in my entire life. For example, sea birds eat mussels on muddy beaches and clams on cobblestone ones. They carry the hard shells in the air and drop them on rocks, breaking them open to reveal the animal hiding within. Apparently I arrived at these two beaches just after lunch, when the tide hadn’t cleaned up the dishes yet.
I’m going to pay more attention to fauna and flora in my future posts.
I don’t know anything about biology, so all plants and animals identified in this post came from CoPilot (AKA ChatGPT). I didn’t check their identifications because it wasn’t worth the hours that would have required. This is not a research paper. I’m just going out into the world and observing through my dirty, discolored glasses.
But now I can see living things…
Active Delta Accretion at Dash Point State Park
INTRODUCTION
Puget Sound is a complex water body with many channels and bays, all of them within a couple of hours drive from my home in Tacoma. I haven’t posted much about this because I’ve been overwhelmed by so many active sedimentological processes that are neither marine nor fluvial. But I had to say something about what we discovered on this short trip, less than 30 minutes from our house. Because of the bluffs (~300 feet) surrounding Puget Sound, streams draining into the various inlets and bays are short and relatively steep. There are exceptions of course, such as the Nisqually River, which flows from Mt. Rainier to the southern end of Puget Sound; however, short streams are very common although many of them have been incorporated into municipal storm drainage systems. Today, we found one that was in an almost natural state.
Figure 1. This photo, looking landward from Dash Point beach, says it all: A small stream enters between the two bluffs, each about 200 feet in height, and dumps copious amounts of sand, silt and clay onto a mesotidal shoreline (the tidal range is about 7 feet), where the volume of sediment input overwhelms the nearshore wave and tidal regime to create an expanding delta.
Figure 2. (A) Regional map showing the complex, glacially sculpted, morphology of Puget Sound. The star is approximately where my house is. (B) Google Earth image from about 7000 feet showing Dash Point and the extensive delta being constructed by sediment delivered by a small stream.
Figure 3. The small stream feeding the delta has been confined to a stone-lined channel. This is the entire inflow. The water looks pretty clear, but appearances can be deceiving in the context of sediment transport. This is a bedload-dominated stream, which means that it is mostly transporting sand and silt, and minimal clay particles. The entire area surrounding Puget Sound is constructed of glacial till, which is mostly gravel and sand. A closer examination will confirm this inference.
Figure 4. This is the delta seen in Fig. 2B during an ebbing tide that is near its minimum. The expanse of the delta, at approximately the same tidal height, is seen here at ground level, revealing tidal channels and swales; but the surface is sand and silt with minimal clay restricted to the swales, like those seen in the middle of this photo.
Figure 5. The flattened sea grass serves as a current indicator that perfectly matches the ripple orientation. Note that the tops of the ripples are flattened by the high velocity of the ebbing tide. Waves weren’t very large on this particular day.
Figure 6. Sand bars are constantly being created and destroyed at the fringe of the delta, probably in seasonal cycles. I don’t know where a late February date fits into this cycle. Perhaps I’ll need to return in the summer.
Figure 7. The delta was less symmetric on this February day than the undated image in Fig. 2B. This image looks to the west. It reveals multiple shore-perpendicular sand bars, until the delta is interrupted by shoreline development. Nothing like this was present on the eastern side of the delta on this day. The sediment supplied by the stream in Fig. 3 is being transported westward in this shallow water, but not by waves like we saw on this day, which are perpendicular to the shore.
SUMMARY
Dash Point beach provided a great opportunity to study nearshore sedimentology. Just look at those ripples in Fig. 7! Despite being created and destroyed twice a day, we find rocks preserving similar ripples throughout geologic time.
With so much gravel in the Puget Sound area eroded from the glacial till (gravel and sand), it was exciting to see finer grained sedimentation occurring in real time. Gravel beaches are uncommon in the geologic record whereas rippled, sandy beaches are very common; after all, the previous source of this sand and silt was a glacial till, itself the product of erosion by ice and fluvial transport during the previous twenty-thousand years.
Material is recycled by our tectonically active planet.
Earth abides…
Timothy R. Keen 
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