Pioneering Botanist Frank Tweedy, from Boom to Bust

Tweedy's Pussypaws, Lewisiopsis tweedyi, is one of at least 35 species named for topographer and botanist Frank Tweedy. Thayne Tuason photo.

In the summer of 1882, in the Cascade Mountains of Washington Territory, three men left Snoqualmie Pass to climb a high peak nearby. One of them stopped occasionally to examine wildflowers—a passion he came to regret when he realized he had fallen behind. He shouted repeatedly. But the responses were so faint they could have been echos. "I wandered all day and climbed several peaks," he would write many years later (Tweedy 1926).

Frank Tweedy was an assistant topographer with the Northern Transcontinental Survey, which was in the process of establishing a railroad route to the coast. The boss, R.U. Goode, had hoped to set up a survey station on a peak near Snoqualmie Pass, but Tweedy carried the theodolite (for measuring angles). Because of his botanical dawdling, the day ended in failure.

"You jolly well made an ass of yourself!" Tweedy fumed, while waiting for the others to return to camp. But to his surprise, he wasn't fired. Instead Goode calmly explained, "You can't make a success of two things, botany and topography both, at the same time." But Goode was wrong.

Frank Tweedy, date unknown. Union College archives, used with permission.

New England Beginnings

Frank Tweedy was born in New York City in 1854. After graduating from Union College (Schenectady) with a degree in civil engineering, he spent four field seasons surveying and mapping for the Adirondack Survey. He also collected plants.

Tweedy's botanical training remains a mystery, but his specimens show he was a serious and able botanist (1). He didn't shy away from difficult groups, and apparently found wetland plants especially interesting, collecting bulrushes, pondweeds, bladderworts, and numerous sedges. He published his discoveries—state records and notable range extensions—in the Bulletin of the Torrey Botanical Club.

Tweedy specimen (in part) of Northeastern Bladderwort, Utricularia resupinata. "I do not think it uncommon through northern New York," he reported in 1880. US National Herbarium, scale in cm; added color photo by Doug McGrady (CC BY 2.0).

To the American West, Land of Discovery

Tweedy's botanizing underwent a radical change in 1882, when he was hired by the Northern Transcontinental Survey and sent to Washington Territory. No longer need he concern himself with range extensions. This was a botanical frontier, largely unexplored. A sharp-eyed collector might well find "novelties"—species new to science!

During two seasons of survey with the NTS, Tweedy made at least 112 plant collections, representing 90 species. Among them was a reedgrass grass from the Wenatchee Mountains, which Frank Lamson-Scribner, an expert on grasses, recognized as a new species—Deyeuxia tweedyi (now Calamagrostis tweedyi). This was the first of many novelties named to honor Frank Tweedy.

Tweedy's Reedgrass, from American Grasses by Frank Lamson-Scribner, 1897.

In 1884, Tweedy joined the US Geological Survey in Yellowstone National Park, where he surveyed for four topographic maps, made 605 plant collections, and published the highly-respected Flora of the Yellowstone National Park (1886). Among his collections were several novelties, including Tweedy's Plantain, Plantago tweedyi.

Tweedy's Plantain. Andrey Zharkikh photo.

Tweedy worked for the USGS in the Rocky Mountains for two decades, collecting plants wherever he went. Among his more productive projects were the Livingstone and Dillon topographic maps in southwest Montana, where he nabbed at least ten new species, including Tweedy's Daisy, Snowlover, and Thistle (Erigeron tweedyi, Chionophila tweedyi, and Cirsium tweedyi [now part of C. eatonii]).

Chionophila tweedyi, Tweedy's Snowlover. Matt Lavin photo.

But it was in Colorado that Tweedy hit the jackpot ... or so it appeared. In the 1890s and early 1900s, while working on the Telluride, Durango, Boulder and Central City topographic maps, he made well over a thousand collections, some twenty of which were determined to be new species! Yet if we check current Colorado plant lists, we find nearly all of those novelties have vanished.

Names Come and Names Go

As budding botanists, we're taught to use scientific names in spite of the off-putting Latin. We're told they are unambiguous, universal, and enduring. But then when we go out into the real world, we learn otherwise. Scientific names do change, and more frequently than some of us would like!

There are many reasons for name changes, but one is especially common—the "law of priority" (Mori 2013). If a given species is described and named by more than one botanist, the first-published name is accepted (others become synonyms). The law of priority was frequently broken in the 19th-century American West, understandably. Floras and relevant literature were inaccessible or non-existent, and communication with other botanists was slow at best.

In the case of Frank Tweedy's discoveries, an additional factor was at play. Like many plant collectors then, he sent specimens of interest to experts at botanical institutions. They decided which were new species, and then described and named them.

Per Axel Rydberg, author of Flora of the Rocky Mountains and adjacent plains (1917).

Tweedy sent many of his specimens to Per Axel Rydberg at the New York Botanical Garden, an expert on Rocky Mountain plants and a notorious splitter. He often recognized new species based on what others considered minor details (Tiehm & Stafleu 1990). Indeed, many of Tweedy's novelties that were named and published by Rydberg did not survive later taxonomic study. Of the twenty supposed new species from Colorado, only one has survived—the North Park or Sagebrush Beardtongue.

In 1901, Tweedy was surveying the Encampment mining district, which was mostly in southern Wyoming. However, "By reason of the faulty determination of the forty first parallel ... the State boundary was located approximately one third of a mile north of its proper position [and] consequently a narrow strip along the southern edge of the district ... is in the State of Colorado" (Spencer 1904). It was in this sliver of Colorado that Tweedy collected an interesting beardtongue. He sent the specimen to Rydberg, who designated it the holotype (basis for description) for a new species, Penstemon cyathophorus.

Tweedy's 1901 North Park Beardtongue specimen (US National Herbarium). Click to view 4 exserted stamens circled in the added closeup .

Today's botanists find the North Park Beardtongue difficult to identify with confidence unless it's in full flower. It's quite similar to Harrington's Beardtongue, differing mainly in the number of stamens exserted prominently (not just a little!) beyond the corolla lip—four in Penstemon cyathophorus, two in P. harringtonii. Despite the subtle distinction, this Rydberg species has survived its latest trial—update of the genus Penstemon for the Flora of North America.

End of an Era

Why did Tweedy find only one true novelty in Colorado? The answer probably is timing. Though the Rockies would continue to yield new plant species, the great era of botanical exploration was coming to a close by the early 1900s. No longer could a sharp-eyed plant collector rake in novelties (Williams 2003).

Did Tweedy realize what was happening? Is that why his large-scale botanizing ended after his Colorado projects? We don't know. In any case, after a field season in New Mexico, he worked for the USGS in Washington DC until his retirement in 1926. He lived another decade before passing away in 1937 at age 83 (Lesica & Kruckeberg 2017).

In his day, Frank Tweedy was highly respected as a pioneering botanist in the American West, with at least 35 species named in his honor. So it's surprising how few of today's botanists have heard of him. And until a few years ago, his presence online was negligible. But that has changed. Now there's a Wikipedia article where you can learn more about Tweedy's successful endeavors "in both botany and topography, at the same time." (2)

P.A. Rydberg named Ivesia tweedyi for Frank Tweedy, who made the first collection in 1883, in Washington Territory. Photo by brewbooks.

Notes

(1) The SEINet Portal Network is the source of information here about Tweedy specimens, unless noted otherwise. Digitization of herbaria is a work in progress; counts likely will change.

(2) Despite his early reprimand, R.U. Goode likely approved of Tweedy's double successes, for he became a close friend, and served as best man at Tweedy's wedding.

Sources (in addition to links in text)

Lesica, P and Kruckeberg, A. 2017. Frank Tweedy (1854–1937) in Potter, R, and Lesica, P (eds.). Montana's Pioneer Botanists: exploring the mountains and prairies. Montana Native Plant Society.

Spencer, AC. 1904. Copper deposits of the Encampment District, Wyoming. USGS Prof. Paper 25.

Tiehm, A, and Stafleu, FA. 1990. Per Axel Rydberg: a biography, bibliography, and list of his taxa. NY Bot. Gar. Mem. 58 (75 pp).

Tweedy, F. 1926. The Confessions of a Tenderfoot. Unpublished memoir.

Williams, RL. 2003. A Region of Astonishing Beauty—the botanical exploration of the Rocky Mountains. Roberts Rinehart Publishers.

Tweedy's Pussypaws' Tortuous Taxonomic Journey

Tweedy's pussypaws has long challenged plant taxonomists. Should they abandon Darwinian evolution for an alternative? Photo by Hike395.

Tweedy's pussypaws lives here! Tronsen Ridge, Wenatchee Mountains. Photo by brewbooks.

In the summer of 1883, in the Wenatchee Mountains of Washington Territory, Frank Tweedy and T.S. Brandegee went exploring, perhaps hoping to climb Mt. Stuart. En route they spotted striking plants among the rocks, with thick roots, broad fleshy basal leaves, and salmon-pink flowers an inch across. They collected one plant, and once back in camp, arranged it carefully in a plant press for drying. It would be sent to the great North American botanist, Asa Gray, at Harvard.

Specimen 37514, Gray Herbarium, Harvard. Washington Territory, 1883 ("Mt. Stewart" is Mt. Stuart).

Minor damage and loss of color due to long drying time (no other option on early expeditions). Material was removed from the fragment packet for imaging.

Frank Tweedy was a civil engineer, with a degree from Union College (New York). After graduation, he worked as a surveyor in the Adirondack Mountains, followed by a stint as sanitation engineer in Newport, Rhode Island. All the while he collected prodigiously, publishing notable finds in the Bulletin of the Torrey Botanical Club. Then in 1882, he boarded a train and headed west.

Townshend Stith Brandegee was a civil engineer with two degrees from Yale, the second in botany. By the time he collected with Tweedy in the Wenatchees, he was well-respected for his botanical knowledge of the American West, having been on four survey expeditions. Several of Brandegee's articles in the Botanical Gazette—Flowers and Snow and Timber Line in the Wasatch Range—show his attentiveness to plant ecology as well as floristics.

Left: Frank Tweedy, 1875. Union College Special Collections. Right: Townshend Stith Brandegee, date unknown. Jepson Herbaria Archives, U. California, Berkeley.

In 1882, Tweedy and Brandegee were hired by Richard U. Goode of the Northern Transcontinental Survey (NTS), which was established to lay out a route for the nation's northern railway. Both men were surveyors professionally, but it was no secret that plants were their passion. In fact, they were encouraged to collect [1]. On August 5, 1893, Goode wrote in his diary, "Yesterday Mr. Tweedy collected for me over 60 kinds of flower-bearing plants within a few rods of camp. They are now being dried ...".

Frank Tweedy found himself in an exciting new botanical world. Not only was the flora unfamiliar to him, it was poorly-known in general, thereby offering fresh thrills—novelties! Unfortunately this term has largely fallen out of use; now we call them "species new to science".

We don't know what Tweedy and Brandegee thought of the plant they found near Mt. Stuart. The oldest label on their specimen (see image below) indicates they didn't realize it was a novelty. Based on the label, it appears Brandegee thought it was Claytonia megarhiza, the fell-fields claytonia—a related plant also found in talus and scree in western mountains.

But attached to the upper right corner of the sheet is a message from botanist William Marriott Canby (head of Economic Botany for the NTS) absolving Brandegee. There was a mixup in labels! Canby wrote, "Tweedy has just sent me his #s 898 and 900 Coll[ected] 1893. #898 is Calandrinia Tweedyi and 900 is Claytonia megarrhiza."

The next oldest label (bottom right corner, below Brandegee's) documents Professor Gray's decision that the plant was a novelty. He named it in Tweedy's honor, writing "Calandrinia tweedyi" on the label—but only after crossing out "brandegei"!

Brandegee label above, Gray annotation below; note edit (red arrow). "TYPE" (blue arrow) marks this specimen as the holotype, the basis for describing the new species, Calandrina tweedyi.

What was the reason for Gray's edit? Perhaps friction between Brandegee and Gray was already developing, one more example of the growing rift between field botanists and "experts" in academic institutions. "they held Gray in high esteem and generally agreed with his scientific principles, [but] the Brandegees [2] eventually claimed a superior ability to classify and appropriately name the plants they had collected ..." (Carter 2011).

Specimen V211615, U. British Columbia Herbarium. Washington, 1996. Faster drying makes better specimens. Note the different name on the label.

In school, budding botanists are taught to use standardized plant names made of Latin(ized) words—known as scientific names. Whereas common names vary from region to region, a plant has only one scientific name ... or so we're assured. But that's only true if taxonomists keep their mitts off it.

Scientific names are intended to reflect evolutionary relationships. For example, species in a given genus are thought to be closely related, evolved from a common ancestor. But sometimes it's hard to decide in which genus a species belongs, and as our understanding evolves, name changes may be needed [3]. Tweedy's pussypaws has been especially difficult in this regard.

Click on image for a "clearer" view.

Asa Gray (far left above) devoted his last decade to his life goal—the Synoptical Flora of North America, a compendium of all known species ordered by evolutionary relationships (Gray was a strong proponent of Darwinism). Several volumes were published before his death in 1888, but volume 1 part 1, which included Tweedy's pussypaws, wouldn't appear until 1895-97 (published in fascicles).

By that time, the pussypaws had been renamed twice! In 1893, Thomas Jefferson Howell, a well-respected self-taught botanist in the Pacific Northwest, moved it and several thick-rooted relatives to a new genus, Oreobroma—"a natural genus, named in allusion to the edible fleshy roots." He made the name change himself, being long frustrated with decisions by experts far away. "... the books and papers [of the experts] relating to these plants present many incongruities, according to the views of field botanists who are better acquainted with the real characteristics of the plants."

But Oreobroma tweedyi didn't last long. The next name change appeared just a few years later in Gray's Synoptical Flora, by then under the leadership of protégé Benjamin Lincoln Robinson. Robinson saw no need for a new genus, instead assigning Tweedy's pussypaws to Lewisia, where it rested for almost a century.

In the mid 1990s, Rafaël Govaerts at the Royal Botanic Gardens, Kew, moved the pussypaws from Lewisia to Lewisiopsis, another new genus. This was one of many name changes he published in the World Checklist of Seed Plants, without explanation! This drew loud criticism, understandably (see Schmid 1996).

Govaerts's decision was not accepted. In Flora of North America (FNA, 2003)—considered the definitive treatment for North American plants—Tweedy's pussypaws became Cistanthe tweedyi [4], based on work by Mark Hershkovitz. However, the FNA authors finished with a warning: based on DNA analyses, "inclusion of [Tweedy's pussypaws] appears to be somewhat equivocal and it might best be treated as a distinct genus."

Tweedy's pussypaws is popular with gardeners, and has received the Royal Horticultural Society’s Award of Garden Merit. From Curtis's Botanical Magazine, 1899 (more here).

This story ends (for now) in Santiago, Chile, where Hershkovitz, who had studied Cistanthe and its relatives for years, was dismissed from the University for lack of funding. Living on the streets with support from friends, strangers, McDonalds employees, and the Reshet Foundation, he "abandoned mathematical interventions and statistical analyses" and considered alternative evolutionary models. Tweedy's pussypaws is likely a hybrid, explaining its similarity to both Lewisia and Cistanthe. Hershkovitz called it Lewisiopsis tweedyi.

Speciation by hybridization is not some wild idea from a crazed street person. In fact, it's now (finally) widely accepted that "The origin of species is more complex than Darwin envisaged ..." For more, see How hybrids have upturned evolutionary theory in The Economist.

Tweedy's pussypaws by any name would be just as lovely! Photo by Richard Droker.

Notes

[1] In the mid to late 19th century, natural history was at its heyday in North America. Exploratory expeditions often included a botanist.

[2] Wife Katherine Brandegee also was a botanist. The couple made many important and long-lasting botanical contributions, especially in California and Baja California (see Carter's excellent article).

[3] It has been proposed that plants be given names independent of evolutionary relationships. Then they wouldn't have to be changed as our understanding changes. I have just a vague memory of this, from systematics classes 40 years ago. If you're familiar with such proposals, please leave a Comment.

[4] Currently, three names are commonly used: Lewisia tweedyi; Lewisiopsis tweedyi, e.g., in Wikipedia and among gardeners; and Cistanthe tweedyi, which seems to be the most popular one among taxonomists, at least for now.

Acknowledgements and Sources (in addition to links in post)

Once again, a huge "thanks" to Biodiversity Heritage Library for providing quick and easy access to older botanical literature. I couldn't have done this without you! Tropicos Name Search was essential for tracing the tortuous path of Tweedy's pussypaws—both its names and the characters involved. 

Carter, Nancy Carol (2011). "The Brandegees: Leading Botanists in San Diego." Journal of San Diego History. 14 (4): 191–216. PDF

Goode, R.U. 1883 (1990). Ed. C.W. Tazewell. The Goode Diary: A personal journal of the Northern Transcontinental Survey, 1883. Virginia Beach: WS Dawson Co., 1990.

Govaerts, Rafaël. 1999. (ca. 1996 originally). World Checklist of Seed Plants 3(1): 21. (Lewisiopsis tweedyi)

Gray, A. 1887. Contributions to American botany. Proc. Amer. Acad. Arts 22:270-314. (Calandrinia tweedyi)

Hershkovitz, M.A. 1990. Nomenclatural changes in Portulacaceae. Phytologia 68:267-270. (Cistanthe tweedyi)

Hershkovitz, M.A. 2019. Systematics, evolution, and phylogeography of Montiaceae (Portulacaceae). Phytoneuron 2019-27:1–77. Don't miss the Acknowledgements, p. 65 (Lewisiopsis tweedyi)

Howell, T.J. 1893. Rearrangement of American Portulacaceae. Erythea 1(2): 32. (Oreobroma tweedyi)

Lesica, P., and Kruckeberg, A. 2017. Frank Tweedy (1854-1937); in Potter, R., and Lesica, P., eds. Montana's Pioneer Botanists. Montana Native Plant Society.

Robinson, B.L. 1895-97. Lewisia; in Gray, A. Synoptical flora of North America, v. 1 pt. 1. (Lewisia tweedyi)

Schmid, R.C. 1996. Govaerts, Rafael. "World checklist of seed plants" [book review]. Taxon 45:579-580.

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.

How the Palouse was Lost

On the Outlaws Trail by Sharon Bodily.  Available at Western Art Association Auction Art.

“I tell ya Tom ... there was a time when these hills were all in grass, rich and lush and filled with flowers in the summer.  Deer and cattle grew fat, there was plenty for all.  Then came the farmers.  They fenced, they plowed, they built houses, roads and towns.  I miss the old times.  They were wild, there were outlaws, a man had to fend for himself ... but at least he was free.”

There’s a kind of grassland in eastern Washington and adjacent Idaho called Palouse Prairie, growing on rolling hills of windblown silt called loess.  Where the loess came from is debated.  Perhaps it was deposited by dust storms during an arid windy interglacial period (Allen et al. 2012).  In any case, the loess forms a thick blanket up to 250 feet thick on top of basalt bedrock (Bjornstad 2006) over an area of many hundreds of square miles.

The Palouse (pah-LOOS); from Wikimedia Commons.

Today's Palouse Prairie in the fall.  Source.

Loess soils are deep and fertile and ideal for grasses.  That’s why the Palouse has largely disappeared -- most of it was plowed and planted with domestic grass (wheat) in the late 1800s.  Like so many North American grasslands on fertile soils, the Palouse Prairie is now an endangered ecosystem (Looney and Eigenbrode 2012).

Photo by Anne McKinnell from her 8 types of Light ebook (recommended!); used with permission.

But farmers were not the only factor in destruction of the Palouse.  There was a time even further back when not only grassland was destroyed but the loess as well.  It was a different time, colder, snowier, with herds of giant beasts roaming the prairie -- caribou, mammoths, long-haired bison, camels.  The rolling grasslands extended uninterrupted for as far as a mammoth or perhaps a hunter could see.  This was during the last glacial advance, at the time of the great floods.

If you’ve been following this series of posts, you know that 15,000 to 18,000 years ago 1) a lobe of the Cordilleran ice sheet extended as far south as Sand Point, Idaho; 2) it impounded a lake of gigantic proportions -- Glacial Lake Missoula; 3) it repeatedly failed; 4) some of the resulting floods were massive, swift and destructive at a scale hard to imagine.  Water hundreds of feet deep roared across eastern Washington at speeds of up to 60 or even 80 miles per hour, traveling some 500 miles to the Pacific coast in only two or three days!

This much water traveling at these speeds is powerful enough to scrape, scour and carry away plants, soil and dirt all the way down to bedrock.  An estimated 16,000 square miles were ravaged, producing mosaics of grassland and scabland, best appreciated from the air.

Anastomosing channels of the scablands; from Google Earth, click photo for better view.

The braided, anastomosing patterns of exposed basalt are highly suggestive of flooding.  Channels split then reunite, very different from familiar drainages where smaller streams consistently join to make larger ones flowing downstream.  The pattern of scabland channels looks very much like “water seeking its way over fresh terrain” in the absence of established drainages (Allen et al. 2012), for example when a creek flows across constantly refreshed sand to the sea.  These patterns are easy to see from the air, but they were first recognized as flood topography before aerial photos were available, by geologist J Harlan Bretz (1923).  At that time, a catastrophe at such a scale was quite a conceptual leap, and many years passed before others accepted his explanation.

You can experience the mosaic of loess and basalt by driving across eastern Washington.  At first the wheat fields seem unending, but then dark objects appear low on the horizon, becoming scattered pines on rough black rock.  Then it’s back to wheat fields -- the Palouse of today.

After all the wheat, we were excited by our first scabland experience, though it was pretty tame compared with what came later!

Scabland in the Telford tract off Interstate 90.  Once/if our government shutdown ends, you can google Telford Washington BLM for more information.

Ponderosa pine in scabland.

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

Sources

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, JH.  1923.  The Channeled Scabland of the Columbia Plateau.  J Geol 31:617-649.

Looney, C, and Eigenbrode, SD.  2012.  Characteristics and distribution of Palouse Prairie remnants.  Nat Areas J 32:75-84.