The Washington State scablands........Lake Missoula glacial dam breach and the massive flood and its geological effects.
J Harlen Bretz
And The Great Scabland Debate
Introduction
One of the most interesting debates in the history of geology has to do with the origins of the Channeled Scabland region in eastern Washington State – so named by J Harlen Bretz because of the region’s distinctive channels with intervening “scabs” of loess or soil covering the underlying basaltic rock. But how, exactly, were these channels and scabs formed? Were they formed over millions of years of time by process of erosion currently active in the region or were they formed by some other means?
By the time of the early twentieth century, the most prominent scientists of the day were decidedly “uniformitarian” in their thinking.1,2 That is, they believed that the regular observed processes of usual geologic events acting over vast periods of time were able to explain most if not all of the observed geologic record. J Harlen Bretz, who earned his Ph.D. in geology from the University of Chicago, was the first geologist to seriously challenge this notion, but it was by no means an easy. The process to change the prevailing dogma of the day was a tremendous struggle for Bretz despite his use of a great deal of very good evidence – and that is what is most interesting about this story.
The Evidence for a Catastrophic Flood
Many people think that scientists are dispassionate in their investigations, conclusions and their general search for truth. As we will soon discover, most scientists have always been very passionate people who, just like most of the rest of us, do not like to admit a long-held error even in the face of otherwise overwhelming evidence.
Bretz’s interest in the Scablands was first aroused in 1910 by the newly published Quincy topography map of the area. This map clearly revealed great potholes now known as the Potholes Cataract. During this same year, Joseph Thomas Pardee published a paper describing the geomorphological evidence for a great glacial lake occupying the intermountain basins of western Montana during the late Pleistocene. He described the prominent horizontal shorelines or “strandlines” previously noted by T. C. Chamberlin. This lake, which was to eventually play a prominent role in this story, was named for Missoula Montana, where its strandlines were particularly prominent. 2
Bretz began the field research of the Scablands in 1922 with the help of a few advanced geology students. He continued these summer outings over the course of seven years, traveling largely byfoot. What he saw was truly remarkable. For example, the cliffs of Dry Falls are 3.5 miles wide and drop some 400 to 600 vertical feet.1,4 By comparison, Niagara Falls is only a measly 1.5 miles wide and drops just 165 vertical feet. Bretz took note of the very steep sides of the channels and their relatively straight pathways as well as the presence of very large gravel bars deposited by water. Also, throughout the scablands Bretz saw huge islands of land protruding from the surrounding landscape with streamlined features as if they were carved by massive torrents of water. 2
Bretz first presented his initial observations in 1923 to the Geological Society of America. In that first paper he simply described what he saw on his various field trips. He deliberately took special care not to present any sort of explanation or interpretation for his observations. He did note, however, that the observed channel erosion required large non-specified quantities of water. On the other hand, in his second 1923 paper Bretz decided to stir up his fellow geologists just a little bit. In the second paper Bretz presented his theory that a truly huge catastrophic flood was in fact the creator of the most prominent features of the Scabland region. 2
Uniformitarian Bias Blinds Scientists
Of course this conclusion was less than enthusiastically received by Bretz’s fellow geologists. In fact, Bretz was openly and vigorously ridiculed for presenting such a ludicrous notion as a flood model for the scablands since this region had obviously been carved out over millions of years by uniformitarian processes. In support of this derision, Pardee’s brief 1922 paper concerning the scabland region near Spokane, Washington (the Cheney-Palouse Scabland Tract) was used to discredit Bretz. In that paper Pardee proposed that unusual glaciation, acting over very long periods of time, created the Scablands.
However, when Bretz went to visit this area a couple years later he found that Pardee’s “glacial” deposits were actually flood bars. What is even more interesting is that, after hearing of Bretz’s ideas, Pardee seemed to change his mind. He actually wrote to Bretz in 1925 suggesting that Bretz consider the draining of a glacial lake as a possible source for his suggested cataclysmic flood. In reference to this communication, Bretz wrote the following to J. C. Merriam:
Mr. Pardee of the Federal Survey, who has seen much of the scablands, has suggested that his glacial Lake Missoula might have afforded the water for these enormous rivers if it were suddenly drained out across the plateau. This comment indicates that his former view of the scablands by land ice and concomitant subglacial drainage under ordinary climatic melting has been abandoned. Even our ultraconservative in Pleistocene geology, Dr. Alden, wrote that the phenomena I describe certainly appear to be river work “if you could only show where all the water came from in so short a time.” 2
Later, in a 1943 correspondence with Hobbs, Pardee himself wrote:
The “drift” referred to in the article Science consists of bouldery deposits which at that time (1922) I interpreted as a gravelly till transported and deposited by glaciers that extended far over the Columbia Plateau. The principal feature of the deposits that suggests glacial action is the presence of large boulder, some of them of foreign origin. From information of the region that has been made available since 1922, however, I have concluded that the deposits are more likely the work of flood waters, such as postulated by Bretz, rather than of glacial ice. That is — I do not regard them as conclusive evidence of glaciation. On the other hand the deposits are indirectly, if not directly, related to glaciation and may have been formed by streams that gouged out the channels and basins under an ice cover as you suggest.2
It seems then that Pardee actually considered the flood hypothesis with Lake Missoula as the source, but was probably dissuaded from pursuing such a heretical notion any further by Alden and Kirk Bryan (Pardee’s superiors at the time). This idea is at least consistent with Pardee’s silence when Bretz presented his rather shocking catastrophic flood idea at the now infamous 1927 “scabland debate”. 2
Sometime before 1927 geologists were catching on to the seriousness of what Bretz was suggesting. If true, Bretz’s theory would undermine the very foundation of Uniformitarianism. Just as anticipated, the general outcry against any hint of a catastrophic model was very loud indeed. In fact, there was a very strong desire to publicly discredit and humiliate Bretz. So, to this purpose, Bretz was asked to present his ideas in public forum to the Geological Society of Washington. Bretz himself was rather unaware of the underlying purpose of this gathering or just how hostile his audience actually was to his ideas. Unawares to Bretz, six “challenging elders”, as Bretz later referred to them, were chosen to counter Bretz’s claims and beat him in public debate.6
The first to speak in response to Bretz’s presentation was W. C. Alden. Alden suggested that many of the features Bretz observed could be explained as collapsed lava caves. He also noted that a flood large enough to create the features observed by Bretz would require an incredible volume of water, and he confidently declared that such a volume of water was simply impossible to achieve. Therefore, another source for the origin of these features must be responsible. Other challengers agreed arguing that the relatively small rivers already existing in the region were in fact responsible, in their current state given enough time, for the observed formations. Instead of a catastrophic flood of magnificent proportions sweeping over the region in a few days they suggested that the rivers took several million years to carve out the scabland features and that Bretz should abandon his ludicrous catastrophic notions.6
Bretz was not easily defeated however. He came to this meeting very well prepared with a great deal of evidence to support his position. He countered all six speakers by pointing out that the channels and bars found in the scablands were much too large, even for a very swollen Columbia River to create over millions of years. The great weight of observational evidence suggested in fact that a huge amount of water traveling at tremendous speed had carved out the entire region in just a few days.2,5,6
Despite the overwhelming evidence in support of Bretz’s interpretations, the “six elders” would have none of it. Nothing would convince them of such a catastrophic model, especially since Bretz was unable to identify or explain the source of so much water. Though the uniformitarian hypothesis did not fit the observed evidence nearly as well as Bretz’s catastrophic model, no one would openly admit to believing Bretz and thus be forced to admit that holy Uniformitarianism was nothing more than an empty dogma.
Though Pardee was at this debate, he said nothing in Bretz’s defense. He simply sat silently listening to the debates. Perhaps if Pardee had spoken up earlier, things might have been different for Bretz. But, as it was, the Uniformitarianism of the geology community was not going to even consider a catastrophic origin for the scabland formations. After all, everybody knew that such geological features were perfectly consistent with slow formation over very long periods of time – even without considering the rather overwhelming fieldwork evidence that Bretz was presenting. So, the opposition against Bretz was vigorously continued for many many years.As Long as it’s Not Noah’s Flood
It was not until June 18, 1940 that things began to slowly change for Bretz. At the American Association for the Advancement of Science in Seattle Washington, many papers were presented in a session entitled, Quaternary Geology of the Pacific, which strongly supported a non-catastrophic origin for the channeled scablands. A post-meeting field trip was also organized during which Richard Foster Flint of Yale University proposed to demonstrate the evidence for the non-cataclysmic model. Bretz was invited to attend both the meetings as well as the field trip, but he refused. Perhaps he was just tired of being constantly held up to public ridicule after so many years? In any case, Flint gave a fine synopsis of his complex argument of proglacial outwash along with stream aggradation and incision. Flint boldly proposed that the surface form of the scabland flood bars was that of “non-paired stream-cut terraces in various states of dissection.” E. T. Hodge followed with his scenario of involving glacial erosion associated with complex damming and diversions by river ice. I. S. Allison then countered Flint just a bit by comparing Flint’s “fill” hypothesis with his own “ice-jam” uniformitarian hypothesis. Finally, Pardee, the eight speaker of the session, spoke benignly about the “Ripple Marks in Glacial Lake Missoula.” 2
In a low key manner Pardee described the huge “ripple marks” of Camas Prairie in northwestern Montana, with heights of up to 15 meters and spacings of as much as 150 meters, as well as his old theory that Lake Missoula was the source of the water that obviously created the unusual current beds found in the Montana prairie region. He went on to suggest that about 2,000 km3 of water were held in the lake and that the evidence showed that a glacial dam had once blocked off the mouth of this lake. He presented convincing evidence, to include severely scoured constrictions in the lake basin, huge bars of current-transported debris, and giant current ripple marks, which all strongly suggested that the ice dam had been breached in a very dramatic fashion.2,3,5,6 Pardee went on to propose that the way this occurred was that the ice dam had blocked the water until the water became deep enough to lift up the ice dam and allow the blocked water to rush out with almost unimaginable force so that the lake was completely emptied within just 48 hours. He suggested that the lobe of the Cordilleran Glacier was the actual plug or dam that blocked the Clark Fork River. This ice dam caused the formation of Lake Missoula (4,150 feet above sea level) to reach a depth of about 2,000 feet over some 3,000 square miles.5 When the ice dam failed, 500 cubic miles of water rushed out of Lake Missoula at 50 to 60 miles per hour (or 9.46 cubic miles per hour), which translates into a 2,000 foot wall of water smashing with Herculean force all the way to the pacific ocean.4Bretz Vindicated
Today it is believed that this huge flood of water rushed across Idaho’s northern Rathdrum Prairie and into eastern Washington where it divided into three huge flows, each up to 600 feet deep traveling at 45 miles per hour. 5 To understand a bit of this magnitude, this flow was ten times more massive than the flow of all the rivers in the entire world today. As this flood raged across the Spokane Valley and out across the loess-covered basalt plateau, it carved out the 20-mile-wide Cheney-Palouse Tract, the 14-mile-wide Crab Creak Channel, and the 50-mile-long Grand Coulee as well as numerous cross or “braded” channels. When blocked by Horse Heaven Hills on the west and the Blue Mountains to the south, the water raced to Walula Gap where the Columbia River heads west to the Pacific Ocean. Since this gap was too narrow to allow the massive flood to flow through fast enough, the flood waters reversed themselves up the Snake River all the way past Lewiston, Idaho. Eventually however, the water drained down to the Pacific and flooded Oregon’s Willamette Valley along the way. During this time, Portland would have been under some 400 feet of water.5
Of course, Pardee’s evidence for the origin of massive amounts of flood waters was just what Bretz needed. This evidence was just enough proof for Bretz to confirm the source for and cause of the watery cataclysm that he knew must be there somewhere. The rest all fell into place since all the information to back up the effects of such a cataclysm had already been ready and waiting for many years. Interestingly enough though, Pardee did not himself state the obvious connection of the Lake Missoula features to the Channeled Scabland features of Washington State. Some have suggested that he generously left that point for Bretz to make.2
In 1952 Bretz made yet another field trip to the scablands and returned with even more evidence to include detailed maps, aerial photographs, and sedimentological information. In his subsequent 1956 paper, Bretz concluded that the most convincing evidence for a cataclysmic flood proved to be the presence of giant current ripples on bar surfaces. These ripples clearly showed that bars up to 30 meters high were completely inundated by phenomenal flows of water. Numerous examples of giant current ripples were found on the same bars that Flint had interpreted as normal river terraces. As it turns out, Pardee’s recognition of the giant current ripples of Lake Missoula was followed by Bretz’s documentation of 15 more scabland ripple fields and then by Baker’s and Nummedal’s identification of 100 more rippled areas. Such features could only have been produced by the flow of very deep water at velocities of truly enormous catastrophic proportions. This was the beginning of early acceptance and painful recognition of the validity of Bretz’s position by geologists.2
Bretz’s remarkable work was built painstakingly over many years, but he had to fight great opposition for many decades for its final acceptance. Finally, in 1979, the geological establishment publicly acknowledged Bretz’s work by awarding him the prestigious Penrose Medal – the most prestigious honor in the field of geology.3 Bretz was in his late 90s, and had been holding the line for more than 50 years before finally realizing general acceptance of his “insane” catastrophic model for the formation of the Channeled Scablands of eastern Washington State.
References
- Allen, J. E., Burns, M., Sargent, S. C., Cataclysms on The Columbia, Timber Press, (1986),Samuel Strok book review for Geology 103 at Bellevue Community College – Winter, 2003 (http://scidiv.bcc.ctc.edu/rv/103/reviews/docs/Strok.ncl )
- Baker, V., Joseph Thomas Pardee and the Spokane Flood Controversy, GSA Today, 5:(9), September 1995 (http://gsahist.org/gsat2/pardee.htm )
- Helfferich, C., Boulders, Braids, and J Harlen Bretz, Alaska Science Forum, Article #1160, November 17, 1993 ( http://www.gi.alaska.edu/ScienceForum/ASF11/1160.html )
- Spokane Astronomical Society, 1998 (http://www.webmaker-nw.com/bustomars/mars-dry-falls-1.html )
- Kids Cosmos, 2001 (http://www.kidscosmos.org/kid-stuff/mars-trip-scablands.html )
- Newman, J., Missoula Floods, Oregon Field Guide, Episode 1001, 2002-2004 (http://www.opb.org/programs/ofg/episodes/1001/missoula/index.php )
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