One of the great unresolved scientific mysteries of our time concerns an extensive body of evidence for extraordinary catastrophic flooding events in the very recent geological history of North America. From the Pacific Coast of Washington State, across the mountains and prairies to the Atlantic Coast of New England, from the region of the Great Lakes to the mouth of the Mississippi, from the arid deserts of the Southwest to the lush forests of the Southern Appalachians, the geomorphological tracks of tremendous floods of truly prodigious scale are etched indelibly into the landscape. Based upon irrefutable field evidence, these colossal floods utterly dwarf anything experienced by modern man within historical times, and yet, by geological standards they occurred exceptionally close to our own time, at the close of the most recent ice age, some 11 to 14 thousand years ago. Familiarity with the currently reigning dogmas regarding the cause of these great ice age floods would leave the casual observer with the impression that the explanation for this diluvial phenomenon has been more or less determined to the satisfaction of a majority of Earth scientists and the work remaining is only in sorting out a few particulars such as the exact number and timing of the floods. However, it is our contention that the model of causation, which is accepted at present by the overwhelming majority of geologists who have investigated the phenomenon, has inherent difficulties. We argue that researchers have not yet grasped an accurate explanation and that the currently accepted hypotheses are beset with unexamined assumptions, inconsistencies and contradictory evidence.

The most impressive evidence for ancient megafloods is found in the Pacific Northwest, primarily in Washington State, Idaho and western Montana. Here the flood features are attributed to a series of events usually referred to as the Missoula Flood, or Floods, and these are blamed upon the repeated failure of a large ice dam that held back an enormous proglacial lake named Lake Missoula, allowing the lake to drain suddenly. The lake is supposed to have occupied the mountain valleys of western Montana, and to have been held in by a large valley glacier in the region of Lake Pend O’rielle in northern Idaho and finally to have drained to the west across southeastern Washington. The floodwater is then assumed to have entered the great valley of the Columbia River from whence it was conveyed to the Pacific Ocean. In the process of Lake Missoula’s repeated draining a massive complex of erosional and depositional features were created that have almost no parallel on Earth.

While they may have been the most spectacular, the Missoula Floods were not the only giant flood events to have occurred in North America as the great Ice Age drew to a close. The effects of mega scale flood flows have been extensively documented in the eastern foothills of the Rocky Mountains in both Canada and the U.S.; across the prairie states; in the vicinity of the Great Lakes; in Pennsylvania and western New York and in New England. All of the Canadian provinces preserve large-scale evidence of gigantic water flows. All regions within or proximal to the area of the last great glaciation show the effects of intense, mega-scale floods.

Complicating the problem is the fact that areas far removed from the immediate proximity of the glaciers have not been spared the ravages of gigantic floods. The arid American southwest preserves extensive evidence of vast flooding on a scale unprecedented in modern times. The Mojave Desert of Southern California is replete with evidence of mighty flood currents drowning entire landscapes. Likewise the Sonoran Desert in Arizona and New Mexico preserves evidence of mighty flood currents. One also finds in the southeastern United States, massive erosional and depositional features in the Appalachians that allow of no other explanation than that of colossal floods. Another great flood is attributed to the catastrophic draining of Lake Bonneville, which, during the latter part of the ice age occupied large intermontane basins in Utah. The Great Salt Lake is but a diminutive remnant of this giant lake. The passage of catastrophic floods has left their mark in Pennsylvania and Western New York.

The scientific documentation of these great floods reaches back into the nineteenth century, with repeated discoveries of various effects that could not be explained by invoking modern fluvial processes operating at a familiar scale, nor could they be explained by invoking glacial phenomenon.

It appears that much of this continent wide flooding occurred during, or at the close of, the most recent ice age. The exact timing of the various events remains to be established. Much of the evidence points to episodic events stretching back tens of thousands of years. However, it also appears that much of this continent wide mega flooding happened concurrently at the end of the last great ice age.

Evidence for megascale flooding at the end of the most recent ice age, is not limited to North America, but has been documented from all over the world. This evidence supports the conclusion that large scale super-flooding events were globally ubiquitous throughout the ice age, but occurred with exceptional power and size at or near its conclusion. Among the places around the planet from which proof is emerging of floods of extraordinary size – Siberia especially, in the Altai Mountains region near the Siberian/Mongolian border, hosts evidence for massive floods equivalent in scale and power to the largest western USA floods. Across northern Europe megaflood evidence is found in abundance. South America, too, shows extensive evidence for massive catastrophic flooding in the recent geological past, as does Australia, New Zealand, the Middle East and Northern Africa. However, for the time being, our focus will be on the great floods of North America. Eventually, however, it will be our goal to document and correlate this imposing mass of evidence for global catastrophe with a view to understanding its origin and causes. Then, we will be in a better position to address the question of social and cultural consequences.

Emerging evidence of earlier mega flood events, apparently associated with global climate changes and transition phases from glacial to interglacial ages implies a non random distribution in time, perhaps periodic or cyclical.

The geographic distribution of megascale flood events also appears to be non-random, certain areas being affected with greater intensity than others. As stated, the Missoula Floods and Siberian floods were, as far as can be determined from field evidence at present, the greatest known freshwater floods in the history of the Earth. Other areas experienced floods of profound magnitude, but, not apparently on the scale of these two events, although the possibility of future discoveries should not be ruled out. The study of megafloods from tsunamis is a related but distinct area of palaeoflood hydrology, which in any comprehensive purview of catastrophism must be addressed. However, for now we shall limit our discussion to floods involving fresh water, meaning events related to glacial melting or rainfall.

The Missoula floods were the most powerful of the great North American floods. The vast scale, the complexity and the sheer magnitude of the forces involved bestow upon these mighty events a preeminent ranking in any accounting of Earth’s great catastrophes. Even a preliminary acquaintance with the awe-inspiring after effects of this extraordinary deluge can provoke a deep sense of wonder and astonishment. Through a more prolonged acquaintance with this landscape and the story that it tells, comes a humbling realization of the almost inconceivable power of the natural forces involved. No flood events even remotely close in scale are documented from anywhere within historical times. They were one of the most significant geological occurrences in the history of the earth. Their magnitude and the release of energies involved rank them with the greatest forces of nature of which we are aware. For a perspective on this refer to these graphs. But again, what renders these diluvial events of exceptional importance and interest is that they occurred only yesterday in the span of geological time, and, most significantly, well within the time of Man.

Let us place the great floods in context. The final phase of the last ice age, the Late Wisconsin, as it is called in reference to North America’s version of the Great Ice Age, came to a conclusion only some 12,000 to 14,000 years ago. While the effects of the ice age were global, the Late Wisconsin itself was the last episode of major ice expansion in North America at the close of the larger cycle of glacial climate called simply the Wisconsin, The final phase known as the Late Wisconsin appears to have lasted from approximately 25 or 26 thousand years before present to around 10 to 12 thousand years before present, depending upon how one defines the precise point of termination. The entire Wisconsin Ice Age lasted for around 100,000 years. While the timing and extent of glacial recessions and expansions throughout the Wisconsin Ice Age is still being worked out, it is clear that the fluctuations of climate and glacial mass during this time were considerably greater than that experience within historical times.

Three ice ages in North America that were earlier than the Wisconsin have been documented by geologists and named after the states in which their glacial effects are best preserved. From oldest to youngest they were the Nebraskan, the Kansan and the Illinoian. Each of these glacial ages was separated from the next by distinct interglacial periods. The warm interval preceding the Wisconsin Ice Age and following the Illinoian is called the Sangamonian. The European counterpart of the Wisconsin Ice Age is called the Würm, which has been extensively documented in the Alps.

The signature of the Wisconsin Ice Age was, obviously, the presence of huge volumes of glacial ice where no such ice now exists. In North America this was most of Canada and a substantial amount of the northern United States. The northern boundary of the great North American ice sheet reached to the Arctic Ocean. From there south to the area now occupied by the Great Lakes the entire region was entirely buried under glacial ice. At the southern glacial margin the ice reached almost to the Ohio River in the eastern half of the U.S. New York lay under a half mile to a mile of ice. Most of the states of Wisconsin and Minnesota were buried as well as the Dakotas. The ice reached out of Canada across what is now the border, from Montana to the Pacific Ocean, with several major incursions further south in Idaho along the Rocky Mountains and in Washington State. Great glaciers also occupied many areas of the Cascades and the Sierra Nevada mountains. In all, some 6 million square miles was buried beneath a mantle of ice, about the same size as that now occupying the South Polar Region on Antarctica. Reference to this map will help to give you the big picture of the Late Wisconsin Ice Age.

At the peak of the Late Wisconsin, around 18,000 to 15,000 years before present, the great ice mass reached from the Atlantic to the Pacific. However, there were actually two separate ice sheets that began separately some 5 to 7 thousand years earlier and eventually grew until they coalesced near the final stage of the Late Wisconsin. The easternmost and the larger of the two was named the Laurentide Ice sheet after a region in Quebec where it appears the ice first began accumulating. This ice sheet appears to have formed from the convergence of two centers of nucleation and outflow, one center to the east of present day Hudson Bay and one to the west. A separate ice sheet formed over the Canadian Rockies and has been designated the Cordilleran Ice Sheet by glaciologists after the collective term for the great mountain chain that forms both the Rocky Mountains and the Andes. As the Late Wisconsin reached its maximum it appears that these three ice sheets coalesced in an essentially single mass. One controversial question relates to the timing and extent of an ice free corridor between the Laurentide and Cordilleran Ice sheets, either prior to their convergence, or after, during the retreat phase. A supposition would be that humans could have utilized such an ice free corridor to migrate to the lower United States from Alaska, after crossing the Bering Land Bridge, which, of course, was exposed during the lowered sea levels of the Ice Age.   

As described in more detail elsewhere, through most of the late Nineteenth century and the first half of the Twentieth, it was believed that the most recent ice age was essentially an unbroken episode of global cooling and ice growth which for the most part continued uninterrupted for some 150 thousand years, or longer. It was also believed that the transitions into and out of an ice age were protracted episodes lasting tens of thousands of years.

However, during the second half of the Twentieth Century, with improved dating, and with more precise and detailed stratigraphy available, it became apparent that the climate changes associated with the onset and termination of ice ages occurred much more rapidly than believed by earlier workers. As the Twentieth Century drew to a close, high-resolution records bore witness to climate changes that occurred with astonishing speed and severity. 

The most recent episode of widespread catastrophic flooding occurred at the termination the Late Wisconsin. Some of these floods were associated directly with melting of the glacial ice. Others are only indirectly linked to glacial melting.  The most powerful of the terminal ice age floods was the complex of events known as the Missoula Flood, although current theory would suggest a much more complex series of floods rather than a single large scale event. The effects of the Missoula Floods can be found imprinted upon the landscape of the Pacific Northwest from western Montana to the Pacific Ocean, and, in addition to Montana include the states of Idaho, Washington and Oregon. Our intention will be to convey an understanding of these awesome floods and to raise some questions concerning important issues that have not yet been answered, nor even addressed under the current state of research.

The other catastrophic floods which occurred during this period of transition out of the ice age, roughly from 13,000 to 11,000 years ago, will be examined in an effort to understand the phenomenon accompanying the end of the Great Ice Age, and which, hopefully, will shed light on the most important question, which remains “What factor, or combination of factors, brought about the abrupt and extreme climate changes which terminated the ice age, and provoked catastrophic melting of the ice complex?”

Our purposes here will be several— first, to acquaint the interested catastrophist researcher with the field evidence which proves the reality of the great floods; second—to present a summary of the scientific thinking and research to date; third—to call into question some of the ingrained dogmas that are invoked in the effort to explain these floods by means of familiar, known processes; and, finally—to offer an alternative hypothesis, one that we believe better fits the evidence and makes greater sense, albeit one that invokes forces from outside the experience of modern historical man.


The Great Missoula Floods


The generally accepted theory as to the cause of the Missoula Flood, or floods, is that a dam of glacial ice, moving out of Canada, filled the mouth of the Clark Fork River just east of its present day confluence with Lake Pend Oreille, near the Idaho-Montana state line. This glacial dam blocked the westward flow of the Clark Fork River causing it to rise against the dam until it eventually reached a depth of close to 2,100 feet, all the while backing up hundreds of miles into the mountain valleys of western Montana. Eventually the lake held over 500 cubic miles of water. At this point, so the theory goes, the dam gave way, allowing the impounded water to flow out across the Idaho Panhandle, through the valley in which the city of Spokane is now located, then to spill out over the great Columbia basalt plateau of eastern Washington, carving a series of branching erosional scars and canyons, flowing south until it reached Wallula Gap, a topographic bottleneck at the southwestern margin of the plateau, from whence it entered the Columbia River Valley to begin the final leg of its journey to the sea. Finally, having traversed the gorge from Wallula Gap the waters crossed the area where Portland is now located, then flowed north and west into the Pacific Ocean. But so great was the volume of flood water that the valley north of Portland could not convey all of it, causing the excess to back-flood far south into the Willamette Valley of Oregon, forming a temporary ponding of water 400 feet deep.

Above the Wallula Gap bottleneck, in the Pasco Basin, the waters backed up into adjacent river valleys such as the Yakima and Walla Walla forming a temporary lake nearly a thousand feet deep. 

While a number of geologists, explorers and researchers played a role in the discovery of the Missoula Flood during the late Nineteenth Century, the two key players during the first half of the Twentieth Century were J Harlan Bretz, a geologist with the University of Chicago and J. T. Pardee with the U.S. Geological Survey. Bretz primarily studied the remarkable erosional and depositional effects over the region of the Columbia basalt plateau in eastern Washington in the early 1920's and proposed catastrophic flooding as the primary cause. To this region he gave the name “Channeled Scabland” after a descriptive colloquialism employed by settlers and farmers for the agriculturally useless land which had been swept clean of topsoil and presented a scarred and scoured appearance to the casual observer. Pardee, on the other hand, studied the evidence for the former existence of a massive body of water, which he assumed to be a lake, in the mountain valleys of western Montana. To this ancient lake he gave the name Glacial Lake Missoula, after the city in Montana that is, at present, located at a place that was at the bottom of one of the primary reservoirs of the lake. At this site the water stood about 1000 feet deep and left visible shorelines along the local mountainsides.

Initially, Bretz’s ideas met with considerable resistance from the geological community, who felt geology had advanced beyond the untenable Diluvialism of earlier generations, which, it was assumed, was based upon scriptural dogmas rather than scientific evidence. The doctrine of Uniformitarianism had only gained ascendancy over rival interpretations a generation earlier and many geologists felt that Bretz was stepping outside the bounds of acceptable convention with his descriptions of colossal catastrophic floods. To these geologists Bretz represented a throwback to a less scientific time. In some ways the uniformity minded geologists can’t be blamed for their initial objections, because, what Bretz was proposing, was in fact, truly incredible. The Doctrine of Uniformity demanded a reference to modern, observable processes in the interpretation and explanation of past events, after Archibald Geikies’ famous dictum that ‘the present is the key to the past,’ and quite frankly, nothing in modern experience even remotely approached the phenomenal scale of the events Bretz was invoking to explain the origin of the Channeled Scabland.

Throughout the Twenties and Thirties Bretz wrote a series of papers describing his findings and responding to his critics. The controversy that raged provides an exceptionally interesting lesson in the workings of the scientific method, and an example of the tenacity with which entrenched dogmas can prevail over widespread evidence to the contrary. Eventually Bretz was vindicated and towards the end of his long life he was the recipient of the Penrose Medal, the highest honor bestowed upon a geologist.

Pardees’ work on Lake Missoula was published in two principle papers which bracketed his career like bookends – his first paper on Lake Missoula was his first professional publication, in 1910, and his second paper was his last, published in 1942 at the conclusion of his professional career with the U.S.G.S.  In the first paper he documented the horizontal lineation on the mountain slopes in the Missoula, Bitteroot and Flathead valleys, which, he realized were shorelines of an ancient lake and these he assumes to have been formed during Ice Age times by glacial damming somewhere to the west, in the valley of the Clark Fork River. This idea he attributes to geologist T.C. Chamberlin who studied the geology of western Montana in the late 19th Century. In his final paper he cites evidence for what he interprets as evidence for rapid draining of Lake Missoula. This evidence includes giant current ripples in Camas Prairie Basin, extensive scouring throughout the valley of the Clark Fork River and large delta deposits at the mouths of various tributary valleys along the major lake drainage routes. 

It is our impression that the theory of a glacially dammed lake, first proposed in the Nineteenth Century by T. C. Chamberlin, has been accepted far too uncritically by Uniformitarian minded geologists, who assume one can simply extrapolate upwards from the conditions of modern ice dammed lakes and the outburst floods which are frequently associated with them. We would suggest, however, that an examination of modern glacial lakes and outburst floods indicates the total inadequacy of glacial ice to act as any kind of barrier to the flow of water under pressures exceeding a couple of hundred pounds per square inch. Pardees’ endorsement of an ice dam formation of Lake Missoula is offered rather tentatively. He states: “Belief that the lake was ice-dammed was suggested by certain of the phenomena of this area, but is based mainly on information derived from the writings of others, from which also the probable location of the dam is determinable.” (Pardee, 1910, The Glacial Lake Missoula, Journal of Geology, vol. 18, no. 4, p. 376) The “writings of others” to which Pardee refers is primarily that of Chamberlin, who only speculated upon the existence of an ice dam but did no investigation of the region of the putative ice dam for actual evidence of such. Upon the strength of this statement, the theory that an ice dam was responsible for the formation of Glacial Lake Missoula ultimately rests, and, hence the corollary that it was the failure of this ice dam and subsequent draining of the impounded lake that created the suite of catastrophic flood features found throughout the region.

The most frequently cited argument by Bretz’s critics was the lack of a source for the prodigious amounts of floodwater, and their rejection of any plausible mechanism capable of provoking the degree of accelerated glacial melting demanded by his theory. Yet, through dogged determination, season after season, Bretz continued to document the field effects that, taken as a whole, could not be explained by any other cause than flooding on a scale totally beyond anything ever imagined by geologists. The ice dam model appeared to provide the means whereby geologists could accept the inevitable implication of Bretz’s massive documentation of catastrophic flooding without betraying the ideal of Uniformitarianism, which had become established as the cornerstone of 20th Century geological thinking.

It should be emphasized that in Bretz’s early work he conjectures that the flooding was caused by accelerated glacial melting, augmented by intensified warm rainfall, possibly associated with a short lived climatic warming. The field evidence he eventually amassed in support of the reality of catastrophic flooding was incontrovertible, and much of that evidence seemed consistent with his concept of combined melting and rainfall, however, he generally neglected the question of causation― what would provoke melting on the scale adequate to produce the magnitude of the flooding implied by the vast erosional complex of the Channeled Scabland. Critics pointed to the lack of any known agency to produce such melting and concluded, therefore, that there had been no floods of the dimension advocated by Bretz.

However, general acceptance of his vision of a vast megaflood sweeping over large portions of the Pacific Northwest began after Pardee’s second publication of 1942.  This paper, already referred to, was rather circumspectly entitled “Unusual Currents in Glacial Lake Missoula, Montana.” Pardee proposes an extremely rapid draining of Lake Missoula due to failure of the hypothetical ice dam suggested in his 1910 paper. It was clear from Pardee’s studies in the Clark Fork River valley that great currents of water had passed through it flowing westward, towards eastern Washington and the Channeled Scablands. From Pardee’s time to the present, with almost no exception, geologists have subscribed to the belief that this flow of water and the ensuing flood was the result of the failure of an ice dam after it had managed to retain a gigantic glacial lake, which, at the region of the ice dam itself would have been at least 2,000 feet deep.

Ice-dammed lakes do presently exist, and sometimes these lakes do burst through their retaining dam of glacier ice, causing locally catastrophic flooding. Additionally, there is in Iceland a type of glacial outburst flood caused by sub glacial volcanic melting that can produce a considerable amount of glacial melt water. This meltwater, under pressure, finds its way to the ice sheet perimeter where it bursts out in the form of a short lived flash flood called in Icelandic “jökulhlaups.” 

The essence of the creed of Uniformitarianism is to explain all past phenomenon in terms of presently observed phenomenon. So, when the theory emerged of an out bursting ice dammed lake, albeit larger than any modern example, it provided the rational needed by Uniformitarianism and thereby appeared to obviate the necessity of abandoning the dogma of modern analogy in order to accept the now virtually indisputable evidence for a diluvial cataclysm. In other words— for years geologists had rejected the idea of a massive flood because no modern, observable mechanism was in operation that could produce the required amounts of water called for by Bretz’s theory, and dogmatic Uniformitarianism demanded exactly that to be considered serious geological science. However, with the appearance of the idea of a glacially dammed lake and subsequent draining, which does, in fact, have a modern counterpart, the requirements of Uniformity were met, i.e. ‘the present is the key to the past.” It didn’t seem to matter that modern, self-dumping glacial lakes and their resulting floods are miniscule when compared with their ancient glacial counterpart in the Pacific Northwest. The tacit assumption was made that one could simply extrapolate upwards as necessary to generate a conceptual framework within which to explain events otherwise utterly beyond anything within modern human experience.

It is perhaps understandable why Bretz, after so many years of rejection, would eventually endorse the ice dam model, because, after all, this model of flood generation was responsible for the belated acceptance of his work by the geological community, never mind that in all of his early work his  interpretation was one of accelerated glacial melting. We can only assume that Bretz finally conceded that no natural mechanism existed capable of melting the quantities of ice necessary to generate such tremendous water flows as implied by the vast erosion of the Columbia Basalt Plateau.

It is not our intention in this limited summary to examine the competing theories offered in response to Bretz’s early interpretations. Suffice it to say that they have been discarded as historical relics. We would state, however, that certain of the alternate ideas offered actually had merit, particularly the work of Ira Allison, who rejected the pace of erosion demanded by Bretz, but in fact proposed a mechanism that undoubtedly did play a significant role in the totality of the process – namely ice berg jamming. We will address Allison’s work in a more extended treatment of this revisionist interpretation in which we shall see that it does more effectively explain certain evidence, namely rhythmical deposition of sediment layers, than do the alternatives.

For our purposes here, let it be explained that during the two decades subsequent to Pardee’s work of the early 1940’s on Glacial Lake Missoula and its draining, the idea of a catastrophic flood gained general acceptance by the geological community. The evolution of Bretz’s thinking during this time, and undoubtedly resulting from additional workers contributing ideas, led him to conclude that rather than a single, extremely large flood, there had actually been a number of catastrophic floods operating over a longer time span. Eventually, he concluded, there may have been as many as seven floods. This, of course, required the formation of multiple Lake Missoula’s and therefore of multiple ice dams, unless it could be shown that there were other potential sources of water. Later geologists, on a number of occasions tentatively offered certain suggestions as to causes and sources, but nothing substantial enough to replace the theory of an out bursting, glacially dammed lake as the sole, or at least the primary cause of the flooding.

It should be emphasized that the evolution to multiple floods began with the abandonment of the idea of accelerated glacial melting and acceptance of the ice dam model. In fact, the ice dam model demanded the endorsement of multiple floods in order to explain the totality of flood-produced features in all their complexity. In fact, as studies evolved into the 1980’s and 90’s it became necessary to invoke as many 80 floods in an effort to account for the shear diversity and widespread distribution of the erosional and depositional phenomena attributed to gigantic water flows. 

With the departure of J Harlan Bretz, who co-authored his last paper on the subject in 1969, a new era of research was embarked upon by a new generation of geologists in the 1970’s. The most important work of this period was probably that of Victor Baker, then with the University of Texas, who analyzed the flood processes in terms of quantitative hydrology, and actually concluded that Bretz’s and Pardee’s estimates as to peak flood volume were too low. He focused primarily on the flood reach in the Spokane Valley, just below the assumed point of flood release in the region of Lake Pend Orielle. His startling conclusion was that through this reach of the flood, peak discharge was some 752,000,000 million cubic feet per second, perhaps even greater. This is a phenomenal water flow. It has been stated that it is some ten times greater than the total combined flow of all rivers on Earth. However, an unresolved discrepancy emerged with the new calculations. Pardee’s 1944 estimate as to the peak flow passing through the Clark Fork Valley, the presumed outflow of the lake subsequent to ice dam breach, was in the order of 390,000,000 cfs. Baker’s estimate indicated a peak flow almost double that calculated by Pardee. To the very limited extent that this discrepancy has been addressed in the literature, it was merely to say that Baker’s more sophisticated formula yielded or more accurate estimate as to actual peak discharge. However, Pardee’s more simple formula

By relying on the mechanism of a glacially dammed lake the larger significance of the Missoula Flood has been obscured. This orthodox model confines the phenomenon of the flood to within the limits of the lower Columbia River watershed. While the flood would admittedly have been a catastrophic event for anyone in its vicinity, certainly anyone in the path of the floodwaters, it would not necessarily be of any consequence to someone living elsewhere on the continent, much less somewhere else on Earth. But we believe that the evidence now in hand indicates that the Missoula Flood was the regional manifestation of a much larger event. The extreme meltwater flooding was not confined to the Channeled Scabland or to the Columbia Gorge, but was present in all areas of the continent with watersheds heading on or near the ice sheet.  In addition, severe flooding effects are also present in most of the watersheds of North America that were not adjacent to the ice sheets. What makes the Missoula Flooding so spectacular are the steep gradients over which the waters traveled on their way to the sea as compared with other meltwater routes discharging from other areas of the ice sheet margin.  In the next part of this exposition we will examine the evidence for trans-continental flooding.


Sources and Reading List


Allen, John Eliot; Burns, Marjorie & Sargent, Sam C. (1986) Cataclysms on the Columbia:  Timber Press, Inc. Portland Oregon.  211 pp.

Alt, David (2001) Glacial Lake Missoula and Its Humongous Floods:  Mountain Press Publishing; Missoula, Montana.  197 pp.

Bjornstad, Bruce (2006) On the Trail of the Ice Age Floods: A geological field guide to the Mid-Columbia Basin:  Keokee Books, Sandpoint, Idaho.  303 pp.

Mason, Charles L. (1996) The Geological History of the Wenatchee Valley and Adjacent Vicinity:  Gig Harbor Press.  172 pp.

Weis, Paul & Newman, William L. (1974) The Channeled Scablands of Eastern Washington; The Geologic Story of the Spokane Flood:  U.S. Dept. of the Interior; 2nd ed. pub. by Eastern Washington University Press (1999)  24 pp.

These books will provide a comprehensive and generally not too technical introduction to the Missoula Flood phenomenon. They all have their merits. Bjornstad’s book is the best and most comprehensive field guide to features in the area of the Channeled Scabland in Washington but does not provide coverage of the Lake Missoula region in Idaho and Montana. This deficiency is balanced by David Alts and Allen, Burns and Sargents books that include sites from those areas. Weis and Newman’s book is the best short and quick introduction to the flood story. Mason’s book focuses on the area of the Wenatchee Valley, as the title indicates.


Some of these articles are written for a general audience but most of them would be considered technical, written for geologists and other scientists in relevant disciplines. We will list some of the more important ones.

Parfit, M. (1995) The Floods that Carved the West:  Smithsonian, vol. 26, no. 1, pp. 48-59.

Bjornstad, B. N. (1980) Sedimentology and Depositional Environment of the Touchet Beds, Walla Walla River Basin, Washington:  Eastern Washington University Masters Thesis, Cheney, Washington,  83 pp.