Thursday, October 31, 2013

Ghosts in the Rocks

See them?  (click on photo for a better view)
The forecast for the day was hot -- 100º F -- but we didn’t bother with an early start.  After all, we were on vacation.  Then we were side-tracked by books and displays at the Visitor Center and fish-and-chips at the stand next-door (very tasty).  By the time we began hiking, it was noon.

From the trailhead below Dry Falls we headed up the west slope of Umatilla Rock, which separates two channels once filled with water hundreds of feet deep that roared along at speeds hard to imagine -- 30, 60, maybe even 80 miles per hour!  Now the channels are dry, rocky and sparsely vegetated.  We were in the scablands of eastern Washington -- land that still hasn’t healed after catastrophic Ice Age Mega-floods scraped off soil and sediment down to bare rock.
It was hard to imagine this being a cold snowy place just 15,000 years ago.
We climbed to a notch and headed down the other side of the ridge into the coulee (above).  There were no trees and no shade ... just rock, rock and more rock, all basalt.  Cliffs of layered basalt stood above slopes of fractured column pieces.  On the coulee floor were massive chunks of basalt entablature that had tumbled when columns were plucked out by floods.  Fortunately, some were large enough to provide a little shade to sit in, which we did.

That’s when I saw them ... ghostly figures standing quite still among the huge dark fallen rocks!
But then maybe it was just the heat ...
Sure enough, a closer look revealed that these were not ghosts at all but rather wild buckwheat plants (Eriogonum sp.).  Wild buckwheats are distinctive and obvious to a western North American field botanist, even when semi-delirious.  The flowers are tiny, with parts in threes, broadly bell-shaped, and arranged in little clusters in cup-like structures called involucres.  But mainly they have the wild-buckwheat vibe -- a set of visual cues that are hard to articulate but easy to recognize once you get to know the group.
These particular buckwheats are covered with fine white hairs -- hence their ghostly appearance.
Above, branched inflorescence with clusters of flowers subtended by involucres.  Below, closeup of tiny flowers (3-6 mm long) in a cup-like involucre.  Photos by Gerald D. Carr; available for non-commercial use at Flora of Eastern Washington and adjacent Idaho.
While I knew this was a wild buckwheat, I didn’t recognize the species.  There are many -- 250 species and 450+ taxa in all (including subspecies and varieties; see Eriogonum in FNA).  They are especially common in arid regions of the western USA, in a wide variety of habitats.  Some are rare and restricted in distribution; quite a few are tough to tell apart and perhaps of questionable taxonomic validity.  All these things suggest that wild buckwheats are a dynamic evolving group, or as we like to say, “actively speciating.”

I decided to name this one “ghost buckwheat” and that’s what we called it whenever we saw it, which was often.  Ghost buckwheat somehow thrives on harsh sites in the scablands, perhaps because it’s clever about where it tries to grow.  Often the sites were more hospitable than they first appeared.  Most provided more runoff or moisture in some way.  Plants were sometimes quite common on talus slopes below cliffs, where runoff might accumulate (below, click on photo for better view).
We saw them on the walls of potholes -- more runoff there too.
Ghost buckwheat on back wall of pothole near Deep Lake.
The healthy plant below is on a gently-sloping field of talus.  Maybe water accumulates among the rocks.
Even where it looked like ghost buckwheat was growing on bare rock, the actual microsites proved to be a bit less harsh, for example a crevice or soil pocket of some kind.
It was always a pleasure to see the ghost buckwheat.  It was in full bloom on those hot dry late summer days when most other plants were done with flowering.  The pale-colored elegantly-arranged stems, leaves and flowers were beautiful against the coarse dark basalt.  So you can imagine my surprise when I tracked it down in some of my botany books and read that 1) it is Eriogonum niveum, the snow buckwheat (I understand, but I think “snow” is not nearly as fitting as “ghost”); and 2) at least one expert considers it to be a “rather unattractive species.”  Here I have to disagree!  It’s lovely in its elegance and pale color, and admirable for its ability to thrive in hot dry rugged environments.  It's certainly a memorable species.  I hope to see it again (I won't be scared next time).
Distribution of Eriogonum niveum, from USDA Plants Database.  “The species is found mainly on the grassy plains east of the Cascade Range in southern British Columbia, west-central Idaho, northeastern Oregon, and eastern Washington” on “sandy to gravelly flats, slopes, bluffs, and rocky, often volcanic outcrops” (FNA).
My music of choice for communing with ghost buckwheat in the scablands would be Chopin’s Etude Op. 10  No. 2 -- also lovely, elegant and mildly terrifying.  This old recording is a bit scratchy, but I like Cortot’s haunting interpretation very much.

P.S. ... Happy Halloween!

This post is part of a series about the Ice Age Mega-floods of the Pacific Northwest.

Monday, October 28, 2013

More vacation fun: kolk lakes & pothole swarms

Might this be the way to Wonderland?
In my most recent post about Ice Age Mega-floods in the Pacific Northwest, I wrote that there were kolks dancing in the torrents.  Of course this was a bit of artistic license.  Kolks hardly dance.  Rather they hammer, gouge, rip, tear, grind, scour, auger and hurl.  Kolks are destructive underwater vortices -- tornado-like currents that can pluck and carry rocks weighing several tons or more!
Whirling kolks plucking and hurling basalt columns; modified from Baker 2009.
The name originated with the Dutch, who observed kolks carrying huge blocks of rock when levees were breached.  Unfortunately the term is sometimes used instead for the holes the vortices make (e.g. in Allen 2009 and the German wikipedia).  In this post, kolks are the powerful swirling flows that do the damage.
"Kolk" sometimes refers to the hole rather than the vortex that drilled it.  Source.
Kolks are thought to be responsible for some of the curious landforms of the scablands of eastern Washington.  When ice dams impounding Glacial Lake Missoula gave way, masses of water hundreds of feet deep sped westward, probably reaching the Pacific coast in just a few days.  The scale of destruction is hard to conceive.  Extensive areas were stripped of vegetation, soil and sediment, exposing basalt bedrock below.  The rock was then sculpted into bizarre and spectacular forms.  These are the scablands.
Scabland buttes in distance; "pinnacles" on left fell from cliff just out of sight.
Colonnade layer in basalt flow.
Columnar basalt is easy pickings for kolks -- quite literally.  Columns readily break into pieces that are plucked and carried off.  The kolk-filled floods dug oodles of holes in scabland basalt.  Some grew and coalesced to make the distinctive butte-and-basin topography of the region.  Smaller ones form the many kolk lakes and potholes.

Kolk lakes

Most of the closed depressions carved out by kolks aren't fed by streams, yet kolk lakes are common in the scablands.  Some are deep enough to reach aquifers, or are fed by springs.
Looking down on Thompson Lake (mid photo) from Steamboat Rock in the Upper Grand Coulee.  Note State Park sewage lagoons nearby.
Deep Lake fills a closed depression almost 2 miles long and as much as 120 feet deep.
Perch Lake below Dry Falls.  Note basalt rubble strewn across bottom of coulee.
Kolk lakes near south end of Lower Grand Coulee.  ArcGIS online; click on photo to view.
At the southern end of the Lower Grand Coulee is a string of lakes, each in its own depression.  They’re connected by an aquifer, and are increasingly saline going downstream due to minerals dissolved from basalt.  The final one is Soap Lake, named for the foam that sometimes develops along the shore, or perhaps for the soapy feel of the water rich in minerals (23 different ones, said to be the most of any body of water on Earth).  It also contains oily ichthyols, probably due to decomposition of tiny shrimp that grow profusely from late spring into summer.
Pacific Apartments, a hotel-sanitarium on the shores of Soap Lake; photo ca 1928.
It’s also possible that the lake's name comes from the Indian word “Smokiam," meaning “healing waters.”  Soap Lake was a popular health resort in the early twentieth century, and while popularity has declined, it's still a destination for health enthusiasts.
Soap Lake is special for another reason -- it’s meromictic.  Unlike most lakes, the warmer surface waters never mix with the cold waters below.  The deep stagnant layer is especially mineral-rich and is inhabited by extremophiles  -- microorganisms able to live in this unusual environment (Bjornstad 2006).


Potholes are smaller, dry depressions.  They’re very common in some of the coulees (old flood channels).  The aerial photo below shows a pothole swarm near Deep Lake; click on the image for details.  Don’t let your eyes fool you -- the round green objects aren’t bumps, they’re vegetated holes in the basalt bench above the lake.  Some are on the order of 50 feet deep.
Deep Lake potholes at Sun Lakes-Dry Falls State Park.  From ArcGIS online.
We took two hikes to explore the Deep Lake potholes.  First we went up on the south coulee rim for views of the lake and pockmarked bench.  Early on, we passed a pothole filled with vegetation (below).  The potholes are more hospitable to plants than the surrounding scabland, I suspect because more water accumulates.
  Note the curious ghost-like clumps on the far wall -- more about these later.
Looking down from the coulee rim at pothole topography on the bench above Deep Lake.
Many potholes are lined with colonnades (columnar basalt layers) -- a nice touch.
Next we took a trail from the Deep Lake parking lot along the south side of the lake looking for a special hole in the basalt cliffs that supposedly would lead us to the bottom of a cavernous pothole, a member of the swarm in the photos above.
Could this be the secret entrance?
Scrambling through the rock tunnel down into the pothole I found ...
... a healthy stand of poison ivy.
In the photo below you can see the fortuitous tunnel that formed in a weak rubbly layer beneath the columns.  Note overhanging entablature above, stronger than the regularly-fractured colonnade and more resistant to erosion.
We carefully walked around the poison ivy, hiked up the opposite slope, and then wandered through the pothole swarm to find our way back to the parking lot.
Where to now?
This fun hike is clearly described in Bruce Bjornstad’s On the Trail of the Ice Age Floods (2006).  It’s short and not strenuous.  A few easy climbing moves are needed to get down into the pothole.  We returned to the trailhead at Deep Lake by way of ridges between potholes ... some exploring required but not difficult, and definitely a fascinating walk!

This post is part of a series about the Ice Age Mega-floods of the Pacific Northwest.


Allen, JE, Burns, M, and Burns, S.  2009.  Cataclysms on the Columbia.  Portland State University, Ooligan Press.

Baker, VR.  2009.  The channeled scabland:  a retrospective.  Ann Rev Earth Planet Sci 37:393-411.  PDF available.

Bjornstad, B.  2006.  On the trail of the ice age floods.  Sandpoint, ID:  Keokee Books.

Monday, October 21, 2013

Fun in the Scablands

In the scablands.  As their name suggests, these are lands that haven't healed.
Try telling friends you went to the scablands of eastern Washington for vacation.  The reaction will be a blank or questioning look and then “Why did you go there?”  Eastern Washington is known mainly for endless wheat fields along Interstate Highway 90, and most people have never heard of the scablands.  Based on the name, they hardly seem a destination of choice.
Geologist J Harlen Bretz was the first to promote the scablands of eastern Washington, in the early 1920s.
The origin of "scabland" often is attributed to geologist J Harlen Bretz, but after reading The Channeled Scablands of the Columbia Plateau (Bretz 1923), I think he was quoting locals rather than inventing a new word:
“The terms ‘scabland’ and ‘scabrock’ are used in the Pacific Northwest to describe areas where denudation has removed or prevented the accumulation of a mantle of soil, and the underlying rock is exposed or covered largely with its own coarse, angular débris.”
Bretz was obsessed with the scablands.  By 1923, he had traveled 3000 miles across eastern Washington by foot and horseback studying, describing and mapping their unique landscapes.  The denudation was extensive -- he mapped some 2000 square miles of bare rock (estimates are now up to 16,000 square miles).  Even more fascinating was the cause of the damage.  Bretz realized it had to have been immense raging ice age floods.

Monster floods were a radical proposal at a time when geologists had rejected catastrophe as the main mechanism of change, favoring instead slow steady processes.  In his 1923 paper, Bretz carefully described the abundant evidence, including 21 scabland features indicative of catastrophic flooding.  In his mind no other explanation would suffice, but he was alone in this view.  Prominent geologists of the day were sure that floods at such a scale were impossible.  In spite of almost universal opposition, Bretz stood firm by his story for 40 years until others finally were persuaded.
An early satellite image (1972) of eastern Washington.  Darker braided areas are scablands, pale areas are mainly wheat, red areas lower left are irrigated fields.  Source.
In the satellite photo above, eastern Washington looks very much like a flood-ravaged landscape with irregular braided, anastomosing channels.  Unfortunately aerial images weren’t available when Bretz was doing his research; he mapped the scablands from the ground (below).
J Harlen Bretz's map of the scablands (1923).  Click on image for larger view.
Today Bretz’s story of catastrophic floods is widely-accepted, and in fact is the subject of nature programs, interpretive centers, many books, a national geologic trail and of course geo-vacations.  That’s why we went to eastern Washington -- to immerse ourselves in damage wrought by ice age floods.

[For more about Glacial Lake Missoula, and the catastrophic floods released when its ice dams failed, see earlier posts in this series.]

Northrup Canyon off the Upper Grand Coulee.
Ice age floods are only part of the scabland story.  The landscapes they carved are composed of basalt -- hard dark coarse rock formed from lava flows.  It's the nature of the basalt that gives the scablands their distinctive look.

Basalt covers a huge area in the Pacific Northwest, though much of it is now buried.  Total extent is on the order of 80,000 square miles, making this the largest collection of lava flows in North America and a certified large igneous province.  Between 17 million and six million years ago, volcanic activity in the Pacific Northwest was intense, especially in the early stages.  In fact most of the lava was produced during the first 1.5 million years, a really short period of time considering the volume.  There may have been as many as 300 high-volume flows (source).  Lava poured forth from linear fissures as far east as Idaho, flowing generally west.  The early eruptions were quite large and the lava more fluid.  Some of it even reached the Pacific coast.
The Columbia River Basalt Group, a large igneous province; from exhibit at Dry Falls Visitor Center. 
By the time of the last ice age, the basalt flows were largely covered with more recent deposits.  Then around 15,000 years ago the megafloods arrived.  Huge masses of water hundreds of feet deep traveling at unbelievable speeds (to 60 or even 80 miles per hour) scraped off grassland, soil and dirt.  The water went to work on the basalt next, sculpting it into the curious landscapes of the scablands.

How could water have carved hard basalt into these spectacular forms?  It’s hard to imagine.  Water can erode all kinds of rock given enough time, but the scablands were created by short-lived floods.  However these were enormous, swift and very powerful floods, with kolks dancing in the torrents -- underwater tornados ripping up basalt!  They easily took advantage of inherent weaknesses in the rock.

When a thick basalt flow hardens into rock, the inner part cools more slowly, and shrinks and cracks in regular patterns, generating striking sets of columns.  In contrast, lava near the surface of the flow cools rapidly; fractures are irregular and discontinuous.  These two zones are called colonnade and entablature.  It was the beautiful colonnades that were exploited by flood waters.
Highly-simplified diagram of several basalt flows showing colonnade and entablature.
The real thing -- colonnade and entablature downstream from Dry Falls.
We found beautiful columns in many places -- like these at the end of Deep Lake near Dry Falls.
Remains of columns line the Deep Lake parking lot.  They’re most often hexagonal, but not always.
It’s perhaps surprising that colonnades are the weaker zones, since entablature is more fractured.  But entablature fractures are irregular, discontinuous and not as “penetrative” whereas those of colonnades are long, continuous and deeper.  Powerful floodwater can readily pluck out column pieces.  Eventually the overlying entablature collapses.
Huge fallen fragments of entablature.
Colonnade under overhanging entablature in Northrop Canyon, accessible via a very pleasant hike.

It's wonderful to tour the scablands and marvel at scenery created 15,000 years ago by monstrous raging floods.  Landforms range from curious to spectacular, and most are easy to spot and understand.  Here are some of the ones we saw.

“Butte-and-basin” or scablands topography

There is a distinctive style to scabland landscapes, due to the resistant basalt and the way it was eroded -- by plucking and collapse.  The channels, buttes and ridges have steep sides, and the channels often are fairly wide, with relatively straight sections.
Scablands topography at Deep Lake, which sits in a large depression carved out by floodwater.  View from a hike in Sun Lakes-Dry Falls State Park.
Near Dry Falls we hiked across and around Umatilla Rock, a narrow ridge left standing where flood waters split into two channels after the big plunge (below).  This is another good place to view colonnade and entablature.
Trekking through scablands near Dry Falls.  Trail passes through smaller notch near left edge of photo.
One late afternoon we scaled Steamboat Rock, a scabland butte.  The trail climbed through multiple basalt layers to the top where we found ... erratics left by glaciers!  Steamboat Rock was covered with ice when a lobe of the Cordilleran ice sheet extended far south.  There also are glacial moraines on the summit.
Steamboat Rock.
View from the trailhead; note multiple basalt flows.
Communing with glacial erratics on the summit -- some kind of granite-like rock.

Coulees (COO-lees)
Looking across the Upper Grand Coulee.  It was dry until the 1940s, but now holds the waters of Banks Lake.
"Coulee" evolved from the French word for flowing, but most coulees in the scablands are dry (or were before being filled with water by engineers). They differ from those elsewhere in North America.  These are giant flood channels, often cut where none existed before, and so aren’t typical V-shaped mature drainages. The bottoms are wider and the walls steeper.
Above is Dry Falls in the Lower Grand Coulee.  The rim is 3.5 miles across, much wider than Niagara Falls.  At peak flood, the surface of the water is thought to have been 400 feet above the rim, and the “falls” probably were more like big bumps in flowing water.  Today the coulee is dry.  The ponds in the old plunge pools are fed by springs.

The Visitor Center at Dry Falls is highly-recommended, for both the views and the helpful information in the displays and bookstore.  You can camp nearby at Sun Lakes-Dry Falls State Park and explore scabland landscapes by driving, hiking, boating and swimming.
Dry Falls Visitor Center sits on the very edge of the coulee.  Views are terrific.
Hanging valleys

Sometimes when large coulees were carved out, existing drainages were left stranded above, creating hanging valleys.  All the ones we came across were dry (it was mid-September).  It would be neat to catch them when they’re flowing and watch water fall down the steep basalt walls into the coulee.

Below is a hanging valley across the Upper Grand Coulee from Steamboat Rock.  Note green patches of vegetation on steep slope below -- perhaps due to seepage from the valley above.

Depressions, potholes and kolk lakes

Holes dug by wildly-dancing kolks in the flood waters were the most fun scabland features we visited -- beautiful lakes, curious caves and mysterious openings.  They are worthy of a separate post ... to follow.
Evening at Rainbow Lake.
At this kolk lake I met up with what looked to be the Creature from the Black Lagoon!

This post is part of a series about the Ice Age Mega-floods of the Pacific Northwest.


Allen, JE, Burns, M, and Burns, S.  2009.  Cataclysms on the Columbia.  Portland State University, Ooligan Press.

Bjornstad, B.  2006.  On the trail of the ice age floods.  Sandpoint, ID:  Keokee Books.

Bretz, J Harlan.  1923.  The channeled scablands of the Columbia Plateau.  J. Geol. 31:617-649.