Sisters visit South Sister (and Green Lakes)

This post covers Day 2 of the Annual Twin Camping Trip: for Day 1 check out Smith Rock Hike: Volcanic Rocks, Volcanic Heat.

twin trip locations

Heather and I woke up bright and early on a chilly morning to get a head start on the popular Green Lakes trail up to the base of South Sister, one of a trio of snow-capped volcanic peaks west of Bend. We hiked Trail 1.7 (traced in yellow on the map below), and stopped for lunch at a very scenic overlook (red dot). Including all our side jaunts, it was a 11 mile round-trip hike with about 1,000 feet of elevation gain from the trailhead to the lakes. We were three thousand feet higher here than at Smith Rock, so thankfully it was much cooler.


Fall Creek is aptly named – and it’s absolutely beautiful!



Just when the ponderosa pines and waterfalls are starting to become routine, the view opens up onto the jagged slopes of the Newberry rhyolitic dome from South Sister’s most recent eruption 2,000 years ago. Although it looks inhospitable it actually is a perfect home for a variety of adorable rodents. A little pika and several yellow-bellied marmots stuck their noses out of the rubble to say hello. Too far away to photograph, alas, you’ll just have to take our word for it. Heather said that the lava flow looked like Mordor from the Lord of the Rings… maybe a lair for the ASBOG Balrog?


Related image

Pika, photo from the National Wildlife Federation

Marmota flaviventris (Yellow Bellied Marmot), Yosemite NP - Diliff.jpg

Marmot, photo from Wikipedia

These lava flows blocked the Fall Creek drainage thoroughly enough that debris and water built up behind them, creating the spectacular Green Lakes!


Almost there…


The very top of North Sister peeked up above the flanks of South and Middle Sister in this shot


Heather contemplates how much work it would take to bring a kayak up here…

As we sat to eat lunch at the overlook we were entertained by the profanity yelled by hikers who decided to gleefully jump into Green Lake only to discover how freezing cold it is, even in August. Let’s just say that when I stuck my feet in the lake to cool off it only took about 10 seconds for them to go numb… I’m not tempted to turn that into a full-body experience.


Ultimate Sisters selfie: Heather, South Sister, and me

We were pretty beat by the time we descended back to the trailhead and happily fell into our hammocks with libations back at Elk Lake. It was another hour or two before we felt like moving again, and we made dinner with the last bits of daylight. Afterwards we took advantage of the clear skies to stargaze – Heather had never seen the Milky Way except in photos. Stupid southeast/east coast light pollution. I’m so glad we could fix that – we had an amazing view not only of our galaxy but of several shooting stars that put on a show! The next morning we packed up camp and headed out on the next adventure to an even bigger volcano: Crater Lake National Park.

But before we leave the Sisters… what were we hiking on?

All three Sisters are part of the High Cascades, the range of distinctive volcanoes in Oregon and Washington that formed between approximately 35 million years ago and the present. I gave a bit of a teaser to their history in my post about Dome Rock in the Western Cascades – I could see the Sisters from there.

Three Sisters annotated photograph viewed from south to North from Broken Top, Oregon.  (Click image to view full size.)

Three Sisters Family Portrait, from their USGS Volcanic Hazards website

The Sisters, while linked together by their names, are not triplets. North Sister is by far the eldest; it was formed between 120,000 to 45,000 years ago by basalt and andesite lavas and eruptions. Middle Sister formed between 40 and 14 thousand years ago, but primarily between 25 and 18 thousand years ago, putting it close in age with South Sister. It is built of andesite, dacite, and rhyolite, and is famous for the archaeologically significant Obsidian Cliffs formed in one of its eruptions that became a tool-making bonanza for Native Americans.

Here’s more specific timeline that I drew for South Sister, based on information from the US Geological Survey Volcanic Hazards Program (USGS VHP).

South Sister eruptive history

You can get an idea of the wide range of eruption ages in the figure below from the Oregon Department of Geology and Mineral Industries (DOGAMI)’s recreation brochure for the area.

DOGAMI eruptive history figure

twin hike map with lava flows

Clip from the DOGAMI recreation map that I edited to show the most recent South Sister Flows from 2,200 to 2,000 years ago: the “Devil’s Chain” flows are in purple while Rock Mesa is outlined in Green. There are so many “Devil’s Whatcha-ma-callit” features in Oregon, some cartographers must have had a flair for the dramatic.

While South Sister hasn’t erupted in two thousand years and the Middle and North Sisters have been dormant even longer, the USGS isn’t ruling out future eruptions.

“The Three Sisters region has hosted volcanic eruptions for hundreds of thousands of years, and future eruptions are a certainty. Two types of volcanoes exist in the region and each poses different hazards. South and Middle Sister are recurrently active over thousands to tens of thousands of years and may either erupt explosively or produce substantial lava domes that could collapse into pyroclastic flows. They could also produce lava flows. In contrast, less explosive eruptions could occur almost anywhere in the surrounding area, and construct small cinder cones to large shield volcanoes made mostly of basalt to andesite lava flows. These volcanoes are typically short-lived (months to centuries) and usually don’t erupt again”

If it’s any reassurance, geologists’ ideas of “a certainty” consider a geologic-scaled timeline up to thousands of years…. so life near the Sisters could well be mercifully boring during our lifetimes.

The hiking here, however, is anything but!




USGS Volcanic hazards page for South Sister:

USGS VHP page for all Three Sisters:

DOGAMI flier for Three Sisters:

In the Playground of Giants Green Lake Field Guide

Photo Credit:


(Marmot) By Diliff – Own work, CC BY-SA 3.0,

Many thanks to Heather van Stolk!!





Smith Rock Hike: Volcanic rocks, volcanic heat

Although we’ve lived in different time zones for a while now, my sister Heather and I have been lucky enough to be able to go camping and hiking together once a year… and we kept up the tradition when she visited me in Oregon!

We set our sights on some classic Oregon landmarks that I hadn’t visited yet either: Smith Rock, South Sister, and Crater Lake.

twin trip locations

Map background from

Fun sights between Corvallis and Bend… Mt. Washington and a very festive Sinclair dino in Sisters.

While this was technically a camping trip we copped out and stayed in a hostel in Bend for the first night – Bunk & Brew – which made up for its scarcity of showers by offering complementary local craft beer. This splurge was totally justifiable because it enabled us to get up at the crack of dawn to beat the crowds to some crazy geology.

26.5 million years ago a massive volcano blew its top in central Oregon, spewing enough ash to enough to cover the state of Texas in a layer about 2 meters thick. The Crooked River Caldera eruption would have been catastrophic for any living thing in the area… just check out the phenomenal remains in the nearby John Day Fossil beds. However it was a boon for modern climbers, because it created the foundation of Smith Rock State Park!John Day Formation

The figure above shows the extent of the Crooked River Caldera (red shape #1) and the two other small eruptions that created the John Day formation, including the Smith Rock Tuff. However the rest of the region’s tuff deposits form low hills, not huge towers – why is Smith Rock so different? It turns out that location is key. Because the park lies within the original caldera, shortly after the tuff was deposited super-heated water carrying dissolved minerals rose up through it. This cemented the tuff much like dilute glue would stiffen sand, combining the best of both worlds for climbing – the funky irregular texture of tuff and the hardness of a sandstone.


(sign in visitor center)

As the ash from that explosion solidified under its own heat and weight it created a rock type known as “tuff”. While that determines its composition, the park’s tuff owes its shape to a very different eruption that started 600,000 years ago – the Newberry caldera fifty miles to the south. It spewed out enough basalt to cover an area the size of Rhode Island. This basalt reaches all the the to the southern margin of Smith Rock State Park, and since basalt is tougher than tuff (ha!) it trapped the Crooked River, forcing it to erode in one place instead of shifting around as rivers prefer. This constrained erosion created the steep pinnacles that make rock climbers starry-eyed.

The photos below show the two sides of the river – steep basalt cliffs on the left, softer tuff on the right.


Someday I’ll get out here with my climbing gear, this summer just wasn’t the chance. Heather and I instead hiked the Misery Ridge trail along the river and up steep switchbacks over the spine of the park. Following very good advice from my friend Kate we decided to do the loop clockwise in order to ascend by the less steep trail and descend on the stairs.

smith rock hike map

map from – we did the loop clockwise

The park is littered with strange hollow rocks, like little fairytale huts for the four-legged park residents. Some are large enough to fit humans!


Heather enjoying the shade

These fantastic shapes were formed by pressurized bubbles in molten but rapidly cooling tuff, and have slowly eroded out of the cliffs. There was a whole village of them near the junction of the River and Misery Ridge Trail.



Looking up at Monkey Face from the River trail. Heather christened my head wear “the typical dorky geologist hat”. I have no shame.


Heather couldn’t resist climbing some more rocks before descending the stairs

Temperatures were predicted to get up to 97 degrees that day so we started at 8:30 AM. After a leisurely stroll along the river and a significantly less leisurely struggle up the ridge we reached the top at 11 AM for a celebratory round of gummy candy overlooking the famous Monkey Face formation.

Scores of people were ascending the stairs at noon as we were passing them going downhill. Several people were prostrate on the side of the trail trying to cool down, and most were markedly miserable.  Smith Rock is a popular park on good roads close to civilization (Bend) and the trail is only 4 miles. This might lure visitors into a sense of complacency but it’s not by any means an easy hike. The signs at the trail heads recommended sturdy boots and drinking a liter of water every two hours while hiking – evidently it’s not exaggeration. I guess the trail is called Misery Ridge for a reason.


I may never climb the 5.14 (insanely difficult) route up Monkey Face, but at least I climbed its mini-me on the playground!


After eating lunch and saying goodbye to Smith rock we stopped by an auto shop to address Jo the Adventure Civic’s warning light (she’s never a fan of the climb over the Cascade passes), and then made our way to the beautiful Elk Lake USFS campsite 45 minutes southwest of Bend. We had a much longer hike planned for the next day, so we settled in for some serious relaxation at the lake shore…


Life is tough 😛


Heather’s wonderful photos!





Accreted terranes: a slow-motion pileup on the Pacific Coast

Oregon became a US State in 1859, so you would think the underlying rock would at least be North American. It turns out that like the modern population of the state, though, southwest Oregon’s bedrock is an international melting pot.

Let’s take a step back and deconstruct that piece of jargon I threw out there in the post title.

Accreted = added on, and terrane = small bit of independent continent.

If you’re familiar with the theory of plate tectonics, it’s often simplified into a huge shifted puzzle of large plates that either collide violently or slide under each other neatly. However there are actually some smaller pieces that get swept up in the cycle of creation and subduction. These could be pieces of oceanic crust that got scraped off of a subducting plate or a volcanic arc like Japan, for instance.

When the supercontinent Pangaea was torn apart by rifts starting around 200 million years ago it started a planet-wide game of bumper cars. The Mid-Atlantic rift separated North America from Europe and it pushed North America westward; this sped up activity along the subduction zones on the continent’s western coast. The Oregon coast shows evidence of the odds and ends of lithosphere that the newly liberated North America plowed into on its journey west.


Figure showing how accretion works, from Miller 2014

The southwest coast of Oregon where my family vacationed is a giant 11-car pileup of accreted terranes ranging in age from 180 million to 100 million years old. When we hiked on Cape Sebastian we were standing on the Gold Beach Terrane, which took an unconventional path to Oregon. Unlike the neighboring terranes that were scraped onto the continent by converged plates from similar latitudes, studies of the rocks found in the Gold Beach Terrane show that they originated near southern California and were transported north on a transform fault similar to the San Andreas!


Closeup of southern Oregon and northern California from Miller 2014 showing the sequence of terranes plastered onto the coast

The most prevalent family of rocks in the Gold Beach terrane is the Otter Point Formation. This melange formation (melange being geology-ese for “ungodly mess of rock types”) contains mostly sandstone with dashes of conglomerate, mudstone, bits of interleafed sandstone and shale, and blocks of misplaced metamorphosed oceanic rock. The sandstone from this formation creates many of the dramatic sea stacks that we saw at Secret Beach, Arch Rock, and near Port Orford.


Arches, mussels, and starfish on the Otter Point Sandstone at Secret Beach

On Myers beach we saw another Otter Point rock that, although softer than the sea stack sandstone, still had a great story to tell.


Turbidite on Myers Beach

These rocks are called turbidite, and were originally deposited in a deep, quiet environment underwater on the continental shelf. The water was so calm at that depth that any storm deposits that rushed out of a delta upslope sorted themselves gently into larger, heavier particles on the bottom and lighter particles on top. Eventually they formed parallel layers of sorted sediment, one per storm event, and were cemented together by pressure and mineralization.

And then their quiet neatness was ruined when the rocks were scraped onto another continent a few million years later.

Now that turbidite has been bent at 90 degree angles, faulted, hoisted above sea level, and is eroding into nice fine beach sand. Not the retirement it was hoping for, I think.


Miller, Marli B. Roadside Geology of Oregon. 2nd ed., Mountain Press Publishing Company, 2014.



Forget rising tides, what about a rising coast? Uplift at Cape Arago

So in my last post I showed off some pretty pictures from Shore Acres State Park… that raise questions.

What’s with the rock blobs?


Why are the cliffs tilted?


And further south, why are all the sea stacks about the same height, and the same height as the mainland?


Unfortunately those blobs are not about to hatch some rock-type Pokemon. They have something much less exotic at their center – small irregularities like pebbles or shell fragments. As groundwater slowly flowed though the sandstone it preferentially deposited minerals on larger particles, creating a snowball effect around imperfections in the otherwise relatively homogeneous rock. This extra “cement” makes those areas harder and more resistant to erosion than the surrounding rock.

The tilting rocks are a reminder of the pressure that the coastline has been under over the millennia – it’s the western edge of north-south trending downward fold, or syncline, that includes all of Cape Arago.

miller 2014 cape arago adjusted

Pressure from the colliding Juan de Fuca and North American plates farther offshore has made the coast buckle and rise over the millennia. Over time the waves wear a flat platform in the rocks, only to have that platform eventually raised out of their reach. There are five different such platforms visible in the Cape Arago area which have been uplifted at a rate of about 3 feet per thousand years.

The lowest visible terrace in the area, called the Whiskey Run Terrace (Q1 in the diagram above), rose from the sea about 80,00 years ago. Although its top might have been elevated above the waves they continued to erode its sides, eventually breaking much of it down into individual sea stacks. Similar terraces and the same wave action occur all along the Oregon coast, creating families of sea stacks with matching elevations.

The uplift isn’t a completely steady process – when the North American plate jolts forward and releases the tension with the subjecting Juan de Fuca plate the coast can plummet a few feet in elevation. However based on the syncline and pattern of older terraces at higher elevations, it seems like upward motion has won the long game.

Image result for oregon coast elevation cascadia quake

Image from Leonard et al. 2004, showing subsidence after quake

I missed an amazing photo op at Sunset Cove near Shore Acres State Park. Apparently at low tide you can see the stumps of trees that were submerged during the Cascadia mega-quake in 1700. I’ll just have to visit again to meet them in person…. not a hardship at all!


Miller, Marli B. Roadside Geology of Oregon. 2nd ed., Mountain Press Publishing Company, 2014.

Lucinda J. Leonard, Roy D. Hyndman, Stephane Mazzotti; Coseismic subsidence in the 1700 great Cascadia earthquake: Coastal estimates versus elastic dislocation models. GSA Bulletin ; 116 (5-6): 655–670. doi:


Family fun on Oregon’s otherworldly southern coast

Like with my Petit Jean State Park trip, I’m going to break this trip up into this travel blog post and another geology post (or posts!).


The last time I got to play in tide pools with my mom I was blond and about 3 feet tall. Twenty years later, it was a wonderful treat to be able to catch hermit crabs with her again! In honor of my sister and my shared birthday as well as our parents’ milestone anniversary, my family flew out to the west coast and stayed in a lodge near Gold Beach, Oregon. From there we explored the Dr. Seuss-ish landscape of the Samuel Boardman Scenic Corridor – a coast full of hidden beaches, huge arches over the crashing waves, and trail-side berry feasts.

We saw so many phenomenal rocky landscapes! I’ve mostly noodled around the headlands of the northern coast – Yaquina Head, Cascade Head, Cape Perpetua, and Cape Lookout – where isolated chunks of basalt form prominent highlands that more successfully resist erosion. There’s no basalt here but the rock formations are phenomenal! I’m looking forward to researching them for future posts.

Shore Acres Park near Coos Bay was a beautiful start to the trip – botanical gardens to keep my mom happy and views that wowed all of us. The hike down to the beach was worth it for the cool spherical features within the sandstone – I’ll definitely have to look up what created them! The park is one of three along a short rugged section of coastline – Cape Arago, Shore Acres, and Sunset Cove would make a wonderful weekend trip. We were just passing through on the way from Florence to Gold beach, so we picked one.


Fantastic sandstone formations


Checking out the mysterious “eggs” in the sandstone at the beach…


My mom loved the dozens of types of dahlias at the Shore Acres gardens

The next day we headed out to Myers Beach south of Gold Beach. My dad felt very much at home – the 55 degree beach weather is pretty similar to what he grew up with in Holland. The views however, were far from it! It’s a nice place for a walk and we found lots of hermit crabs in the tide pools about 1/2 mile north of the parking pull-out. The geology was pretty cool too, and I’ll definitely touch on that in following posts!



The tide pools here were shallow and wave-tossed – good for crabs, but we didn’t see many anemones or snails. The lack of snails seemed to be a bit of a problem for the hermit crabs. Many were stuck in shells a few sizes too small! We were able to catch a few who were too involved in duking it out with a shell competitor to notice the humans crouched above them.

Cape Sebastian features a 3.2 mile round-trip hike from the top of the promontory down to dramatically tilted slabs of sandstone at its base.  However the tide pool creatures were worth it! We saw two chitons – molluscs that look like armored sea slugs and have been around for the past 400 million years. Some of the slabs of rock had tumbled down, creating hidden pools filled with anemones, sea urchins, starfish, and shy purple shore crabs. The downside was that there was an awful lot of “up” on the way back to the parking lot, but it wasn’t too bad since we were fueled by the bounty of ripe huckleberries, salal berries, and thimbleberries along the trail.



Heather’s first thimbleberry


finding chitons!


One of the most diverse tide pools we saw on the trip – 2 types of anemones, sea urchins, starfish, purple shore crabs, and several varieties of sponges.



Clambering up the tilted sandstone slabs at the base of Cape Sebastian

In order to experience the magic of Secret Beach, you have to get your timing just right. It’s only accessible when the tide is below the “zero” of the chart, but it’s definitely worth the hassle. A one mile trail leads you down to a rocky spit overlooking an otherworldly bay full of towering sea stacks topped by battered pine trees and flocks of cormorants. During the lowest tide you can access a string of small beaches and phenomenal arches. We saw whole constellations of star fish here too. Caution is needed though- if you get too engrossed in the sights and the tide comes in you’re stuck until the next day.


We also pulled over at two viewpoints near Secret Beach – unfortunately my photos didn’t turn out though. Arches Rock is the opposite of Secret Beach – it’s an island that you can see it from a short paved trail any time you please. It would make a great photo op when huge waves are breaking on it. I’d recommend bringing binoculars to scope out the birds nesting on top. The Natural Bridges are a beautiful, convoluted set of three arches. Brave souls can take the sketchy unofficial trail from the official lookout that takes you over the narrow top of the bridges. You would have to risk wind, poison ivy, and eroded paths… not something I felt like making my mom watch me do.

After a few days we headed back north towards Corvallis. Along the way we stopped to see the Hecata Head lighthouse:


had an early dinner at Local Ocean in Newport, which was amazing:


Poor Heather, we were all snitching from her monumental seafood stew


My parents in Newport’s harbor. So many beautiful boats!

And after dinner we headed to Yaquina Head to hang out with the seals and a couple thousand murres.


The lighthouse, with the cliffs full of sea birds


Spying on the seals and their adorable babies


Once in Corvallis we were pretty ‘boring’ as far as travel photos go. Mostly just eating good food and enjoying each others’ company, but our last touristy excursion was to Willamette Valley Vineyards. We had a wonderful guide who let me pepper her with questions about the soil and then gave us samples from different terroirs owned by the company.



After a marvelous week, it was so hard saying goodbye to my parents. At least I got to hang onto Heather for a few more days. The mountains were calling, and it was time for our annual twin camping trip. More on that later!





Dome Rock and the continuing trials of Jo, the Adventure Civic

Dome Rock Hike: 10/10 would hike again, magnificent view

Drive to Dome Rock north trail head: 10/10 would NOT attempt again in a 2001 Honda Civic

I had originally planned to hike the 10-mile round trip trail from the Detroit Lake information center up the ridge to Dome Rock, but the ranger at Detroit Lake State Park was quick to discourage me. He suggested that it would be much easier to take the Forest Service road to the northern trailhead and just do the prettiest 3 mile section along the ridge top. Sure! Why not?

18% average slope on gravel roads is why. Having to stop and restart my crotchety old car multiple times on said 18% slopes to move away the fallen rocks so I could get clearance is another good reason.

Luckily the beauty of the hike brought my blood pressure back down again within a mile or so. The trail wound though firs, maples, and thimbleberries (snack time!) along the ridgetop above Tumble Lake.

Map of Dome Rock trail

Map from Willamette National Forest USFS website for trail 3381

Directions to the Tumble Creek North Trailhead can be found here on the USFS site. They aren’t kidding when they say “up steep mountain roads”.


At the top of Dome Rock, selfie with Tumble Lake!


View of Mt. Jefferson and the Three Sisters from the top of Dome Rock.

I was hiking in the Western Cascades, which form the more eroded volcanic predecessor to the striking peaks of the younger High Cascade mountains. Magma rising from the subducting Farallon plate created both zones of the Cascades, but the two stages of that subduction made them distinct. Between 35 and 8 million years ago the plate sank under North America at a slightly steeper angle, resulting in the location of the Western Cascades. Around 7 million years ago that angle became shallower, which moved the depth at which the magma rose off of the melting plate to location further east. (Devis 2013)

Inkedwestern vs high cascade Miller page 110_LI

Figure from page 110 of Marli B. Miller’s classic “Roadside Geology of Oregon” – the area of Dome Rock  is circled in yellow

change in subduction zones Miller page 113

Figure also from “Roadside Geology of Oregon”, page 113, showing how the change in subduction angle influenced the location of volcanoes further inland.

All the classic cone-shaped volcanoes of the Cascades such as Mt. Jefferson, the Three Sisters, and Mt. Hood are part of the High Cascades. In contrast, a few more million years of exposure to rivers and glaciers created the more subdued landscape of the Western Cascades. Any volcanic cones from that era have long been ground down to their roots.


Standing in the Western Cascades, looking at Mt. Jefferson in the High Cascade mountains. Photo taken during one of my stops to move rocks off the road…

Dome Rock itself is one of those “roots” – an isolated piece of 10 million to 17 million year old andesite where newer magma punched through a 30 million to 17 million year old area of tuff (cemented volcanic ash) and basalt. (Walker, G.W., and Duncan, R.A., 1989) It’s relative toughness meant that it withstood the 10 million years of weathering since its formation better than the surrounding formation’s softer tuff with basalt, creating the bare knob with spectacular 360 degree views.


Andesite near the top of Dome Rock… next time I’m hiking with my rock hammer.

Jo’s engine may have nearly overheated on the way up, but at least I didn’t have to use the engine at all for seven miles on the way down. After creeping back down the forest service road using a combination of second gear and brakes, I stopped at a peaceful little day use area along Frenchman Creek to eat my lunch. Judging by the size of the boulders in the creek bed, the stream hasn’t always been so tranquil!


Frenchman Creek day use area, about 1.5 miles north of the intersection with Hwy 22

Zach Urness of the Statesman wrote a helpful article on the Dome Rock/Tumble Lake hikes with more information about the lake and its campsites. I didn’t go down to the lake this time, but maybe next trip.

With all the time that skipping the extra 7 miles of the hike saved me, I stopped by Marion County’s Niagara Park on the North Santiam on the way home. My phone was dead, so no pictures this time, but if I’m by there again I’ll definitely stop to take some. The site was ambitiously called “Niagara” by hopefuls in the late 1890s aiming to build a dam where the Santiam is funneled through a 4-foot-wide crack in the underlying rocks. The dam failed repeatedly and they gave up in 1912, leaving a park with picturesque ruins. About a half-mile up the stream from the failed dam lies a  misshapen mound of rocks eroded into a perfect picnic spot and place to cool your feet off in the river.

I was sorry to have to leave the parks and head back home… and on the way back I got Jo a well-deserved car wash.


My sister posing with Jo the Adventure Civic on another trip that I’ll be blogging about soon!

Field work: Week 2

This past week Jen and I headed back out to the Walla Walla Basin, but primarily for another project: doing the quarterly water level check and data collection download at observation wells in the Umatilla and Walla Walla watersheds. In between monitoring wells we collected the five remaining samples budgeted for the geochemistry project.

After visiting 60 or so wells, each with their standard blue wood-and-aluminum housing, they started to blur together. A few things stood out…

Cozy mouse nests and resident spidersimg_20180709_135009456

Granite boulders 200 miles from where they ought to be


and the earth-shaking exploding munitions that I was discouraged from photographing.

Those munitions were on the Umatilla Army Chemical Depot, where OWRD has a handful of  monitoring wells. Atlas Obscura has an intro and some interesting photos… The site was created during WWII to store weapons and supplies, and since then has been the location for disarmament from weapons stockpiled for use in the Pacific theater of the second World War as well as the Cold War. Our guide said that they had indeed gotten rid of all the chemical weapons stored onsite, and the current mission on the base is making sure that the old explosive weapon destruction pits are done exploding. That explosion while we were sampling was proof that the second look was necessary. The end goal for the site is to render it harmless enough for limited non-military use such as stock grazing.

Not much explanation is needed for the well housing tenants – the structures form hospitable shelters in the middle of wide-open grain fields. A perfect bed-and-breakfast for four-legged or eight-legged creatures. Luckily we didn’t see any of the region’s black widow spiders – just harmless, fuzzy Phidippus audax. For the sake of my arachnophobe friends I won’t post a portrait, but google them if you’re curious. They’re actually kind of cute.

That granite boulder, on the other hand, is a long way from home. Like, 100 to 200 miles. And it’s not a small boulder – it’s about the size of an oven.  Below is a map showing the “closest” granite outcrops in purple, and the location of this lonesome rock with a pink star. What on earth is it doing by a well in Morrow County, Oregon?

pnw granite and erratic

Like so many geological oddities in the Columbia River basin, it hitched a ride on the epic Glacial Lake Missoula floods (shown in blue below)! It likely came from somewhere around Spokane.

pnw granite erratic with floods

Glacial flood extent created by ESRI user jcleveland0, accessed via ESRI Online. Granite outcrops selected from the USGS Preliminary Integrated Geologic Map Databases of the United States shapefiles for OR, WA, MT, ID.

The Missoula Floods were an amazing manifestation of the latest Ice Age between 13,000 and 15,000 radiocarbon years ago. An ice sheet repeatedly dammed a predecessor of the Salmon river at its headwaters in Montana, creating a lake over 200 miles long. Then as water likes to do it eventually blasted through. Again. And again. In each flood event water racing at over 10 million cubic meters per second scoured the landscape in northern Idaho, Eastern Washington, and northern Oregon. These floods meant business, creating ripple marks bigger than houses, amphitheater-sized waterfalls, and topsoil stripped from Spokane to be deposited in Salem. That flow picked up boulders the size of buses only to set them down them hundreds of miles away, so the moderately sized one we saw on our rounds would have been a piece of cake.

The Washington Geologic Survey created a beautiful, user-friendly introductory website for the floods here. I really recommend it! It not only shows the scientific knowledge surrounding the floods, but the process of science that connected all the disparate observations into one phenomenal story. At least, phenomenal if you’re as nerdy as I am.

Our own research for the week was unfortunately nowhere as riveting as this rock’s journey. In the coming weeks I’ll wait with bated breath for the laboratory results, learn how to process four months of water level transducer data for a few dozen wells, and start my literature review. However any blockbuster geologic story like the Missoula floods was assembled out of thousands of seemingly trivial observations, so I’m happy to work away in my own little corner of science.


It’s not a bad-looking corner at all, just a bit hot…