About the “thick ice sheet that melted fast” geomorphology paradigm

Authors

Abstract:

The “thick ice sheet that melted fast” geomorphology paradigm is being introduced in the Missouri River drainage basin research project essays by interpreting large quantities of previously neglected topographic map drainage divide evidence. Fundamental differences between the “thick ice sheet that melted fast” geomorphology paradigm and the prevailing geomorphology paradigm are related to number of ice sheets, elevation of the topographic surface upon which the ice sheet formed, depth of ice sheet erosion, presence of a deep ice sheet-created “hole”, ice sheet thickness, ice sheet relationship to crustal warping and uplift, ice sheet melting rate, melt water flood flow routes, and amount of melt water erosion, to mention just a few.

Paradigms are frameworks upon which future research workers can build and by themselves paradigms are neither correct or incorrect, but instead are evaluated based on how useful they are in solving unsolved research problems. To be considered useful the “thick ice sheet that melted fast” geomorphology paradigm must demonstrate to the geomorphology research community that it offers superior opportunities for solving unsolved geomorphology research problems than the prevailing geomorphology paradigm offers.

The prevailing regional geomorphology paradigm

  • Perhaps the best description of the prevailing regional geomorphology paradigm is found in William Thornbury’s 1965 book, Regional Geomorphology of the United States [1]. While considerable geomorphology research has taken place since 1965, the underlying framework of ideas geomorphology researchers still use when trying to solve problems has not significantly changed. In fact, the prevailing geomorphology paradigm can be traced back much earlier than 1965. In 1931 Nevin Fenneman published his classic work,Physiography of the Western United States [2], in which he summarized problems regional geomorphology researchers had addressed to that date. In doing so, Fenneman defined the regional geomorphology paradigm as it existed in 1931 and also identified a number of problems geomorphology researchers had yet to solve. Interestingly, Thornbury in his 1965 book, while presenting results of research conducted between 1931 and 1965, was not able to report much progress in solving those unsolved regional geomorphology problems. In fact, a close reading of Thornbury’s book reveals numerous unsolved research problems.
  • Since 1965, regional geomorphology as an active research discipline, at least as defined by Thornbury and Fenneman, has almost ceased to exist. While regional geomorphology research of the type Thornbury and Fennenman conducted is today rarely published in scientific journals and/or presented at scientific meetings, geomorphology as a research discipline is thriving. In fact, the Geological Society of America reported in November of 2009 [3] that its Quaternary Geology and Geomorphology Division with 1,630 members was its second largest division. What has happened is the geomorphology research community was unable to solve the regional geomorphology research problems Fenneman and Thornbury identified and has simply moved on to tackle different types of geomorphology research problems. In other words, almost all of the unsolved regional geomorphology problems in 1931 are still unsolved today.

Examples of unsolved regional geomorphology problems

  • Studies leading to the Missouri River drainage basin research project were initiated more than thirty years ago when I tried to solve one of the unsolved problems Thornbury’s book had identified. At the time I was teaching geomorphology and North Dakota geology at Minot State University, which is located in Minot, North Dakota. One of the most obvious Minot area landforms is the Missouri Escarpment, which rises approximately 150 meters in the region immediately south and west from Minot (see map below).
 
Missouri Escarpment and Missouri Coteau southwest of Minot, ND. United States Geological Survey map digitally presented using National Geographic Society TOPO software.
  • Thornbury describes the Missouri Escarpment as follows, “The eastern boundary of the Missouri Plateau is the Missouri Escarpment. This escarpment represents a rise of 500 to 600 feet from the level of the Central Lowlands to the surface of the Missouri Plateau. The origin of this escarpment is uncertain; it apparently is not the product of a particular resistant formation; more likely it marks the boundary between two topographic levels of erosion in the Central Lowlands and the Great Plains.” Here is a major North American landform that has never been satisfactorily explained.
  • My efforts to solve the Missouri Escarpment problem soon led me to neglected southwest North Dakota drainage history problems. One of the most obvious unsolved problems was the asymmetric drainage divide, which provided evidence the north-oriented Little Missouri River had beheaded southeast-oriented drainage routes to the present day Knife, Heart, Cannonball, and Grand Rivers. But just as intriguing were pronounced Knife, Heart, and Cannonball River elbows of capture. West of the elbows of capture these rivers are southeast-oriented, east of the elbows of capture these rivers are northeast-oriented and join the south-oriented Missouri River as barbed tributaries. Thornbury and others describe the northeast-oriented river valley segments as remnants of a northeast-oriented preglacial drainage network, which suggests the Missouri River valley eroded headward along an ice sheet margin.
 
Southwest North Dakota rivers and elbows of capture.National Geographic Society map digitally presented using National Geographic Society TOPO software.
  • While Thornbury’s implication the Missouri River valley eroded headward along an ice sheet’s southwest margin made sense and was consistent with commonly published interpretations, there are no published explanations for the Knife, Heart, and Cannonball River elbows of capture. Further, some published reports suggested the north-oriented Little Missouri River valley had existed in Eocene time, which made no sense at all, considering the easily eroded local bedrock and evidence the Little Missouri River valley had beheaded southeast-oriented flow to the Knife, Heart, Cannonball, Grand River drainage basins.

  • What was even more puzzling were published descriptions of the hypothesized preglacial drainage network. The hypothesized preglacial valleys had been traced in several different published reports across North Dakota and the adjacent Canadian provinces of Saskatchewan and Manitoba, and some of these reports use rather impressive maps to illustrate how these preglacial rivers flowed to Hudson Bay. However, the bedrock in North Dakota, southern Saskatchewan, and southwest Manitoba is easily eroded and much of this region according to commonly published interpretations was supposedly covered with Pleistocene continental ice sheets four or more times. What did not make sense was how could these preglacial river valleys, which had been eroded in easily eroded bedrock, survive the erosive action of continental ice sheets during multiple glacial events, including melt water erosion when each of the multiple continental ice sheets melted?

  • Searching the geologic literature I discovered another geomorphology researcher who was also asking the same questions. William White in 1972 published a paper titled “Deep glacial erosion by continental ice sheets” [4]  in which he suggested deep glacial erosion of more than 120 meters had exposed the Canadian Shield and otherwise significantly altered the North American landscape. However, White’s paper was not well received. Several researchers published scathing criticisms. For example, in 1976 D. E. Sugden published a paper titled “A case against deep erosion of shields by ice sheets” [5] and other critics included Gravenor in 1975 [6]. Among the criticisms raised are the presence of glacial deposits in the hypothesized north-oriented preglacial river valleys and fossil evidence suggesting northern Great Plains topographic surfaces have seen little erosion since middle Cenozoic time. In other words, critics said the river valleys existed before at least the last glaciation. While White’s hypothesis received some support (e.g. Bell and Laine, 1985[7]), the overwhelming majority of the geomorphology research community either rejected it or simply ignored it.

  • Much of what White said made sense to me and was consistent with evidence I was seeing. However, there were legitimate criticisms of White’s hypothesis and until those criticisms could be answered, the hypothesis could go nowhere. Trying to solve an unsolved geomorphology research problem simply led to more unsolved and even more perplexing geomorphology research problems. I then spent several years tracing lag gravels included in western North Dakota alluvial deposits to Rocky Mountain source areas. Those gravel studies convinced me the north-oriented Little Missouri River valley and Yellowstone River valley were not preglacial valleys. However, there was still the problem of glacial deposits in those valleys further to the north.

  • I have not included data from my gravel studies in the Missouri River drainage basin research project essay series. Alluvium I traced has been found in sediments containing Oligocene fossils. Data I gathered convinced me the alluvium had been transported by glacial melt water, which moved along an ice sheet margin. However, paleontologists refuse to budge on the fossil ages. The Missouri River drainage basin research project essay series builds a case for the “thick ice sheet that melted fast” geomorphology paradigm completely independent of the northern Great Plains alluvium deposits, although any converts need to be aware the new paradigm probably challenges previously established and well-accepted sediment and fossil ages.

Evidence leading to a new paradigm

Anastomosing channel complex east of Minot, North Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.
  • Attempting to solve one unsolved regional geomorphology problem simply led to additional unsolved regional geomorphology research problems, far more than can be listed in this brief essay. However, one perplexing problem was solved when A. E. Kehew published an explanation [8] for what I now consider to be an anastomosing channel complex east of Minot. Prior to Kehew’s publications I could not satisfactorily explain the channel complex, nor could other workers who had provided previous explanations. After learning of Kehew’s explanation I was puzzled because I had seen anastomosing channel complexes elsewhere, and some of those other locations were nowhere near an ice sheet or a glacially dammed lake. It took several years before the full implications of Kehew’s explanation began to emerge. During that time I spent many thousands of hours studying detailed topographic maps looking at escarpments, barbed tributaries, elbows of capture, through valleys, and drainage divides.
Boxelder Creek-Little Missouri River drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.
  • What I kept seeing over and over again is illustrated in the Boxelder Creek-Little Missouri River drainage divide map. The drainage divide is crossed by multiple through valleys. Some of the through valleys are large and deep. Other through valleys are much more subtle. Some of the through valleys are little more than saddles notched into high level ridges. But each of these through valleys is evidence of a former drainage route. By looking at drainage divides to the northwest and southeast these former drainage routes could be reconstructed.
  • In the case of the Boxelder Creek-Little Missouri River drainage divide the through valleys provide evidence of multiple southeast-oriented drainage channels, which moved water from what is today the northeast oriented Boxelder Creek drainage basin to what is today the northeast and north oriented Little Missouri River drainage basin. These multiple through valleys are also evidence of a southeast-oriented anastomosing channel complex, which is evidence a large southeast-oriented flood once moved across the drainage divide. Note also how the southeast ends of the through valleys are drained by southeast-oriented streams, which join the northeast-oriented Little Missouri River as barbed tributaries. The southeast-oriented drainage routes were captured by headward erosion of what must have been a deep Little Missouri River valley. Further, note how the northwest ends of the through valleys are drained by northwest-oriented streams. Those northwest-oriented stream valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow channels when headward erosion of the deep northeast-oriented Boxelder Creek valley next beheaded those flood flow channels.
  • Once I realized large floods had crossed drainage divides I started to look for drainage divides, which anastomosing channel complexes had not crossed. During this search drainage divides throughout the United States were systematically studied, and restudied multiple times, because when looking at the east-west continental divide from this new perspective, the evidence said the immense floods had crossed the east-west continental divide (and other high mountain drainage divides). Where had these immense floods originated and how did the flood waters cross what are today high mountain ranges? Answering those questions took many more years of reconstructing flood flow routes, which ultimately led into the heart of what I finally concluded had been a thick North American ice sheet, that had been located in a deep “hole.” The Missouri River drainage basin research project essay series is being written to illustrate what I saw. To properly evaluate the “thick ice sheet that melted fast” geomorphology paradigm the entire essay series needs to be considered.

Why the “thick ice sheet that melted fast” concept is a new regional geomorphology paradigm

  • Thomas Kuhn in his book, The Structure of Scientific Revolutions [9], argues that science is not a steady, cumulative acquisition of knowledge. Instead, science is a series of peaceful interludes punctuated by intellectually violent scientific revolutions. The peaceful interludes are characterized by “research firmly based upon one or more past scientific achievements that some scientific community acknowledges for a time as supplying the foundation for its further practice.” These acknowledged intellectual achievements are called paradigms and normal science according to Kuhn is “an attempt to force nature into the preformed and relatively inflexible box that the paradigm supplies.” There is no effort to discover anomalous evidence, new types of phenomena, or to invent new theory, and there is little tolerance for scientists who try to do so. However, by focusing attention on a small number of relatively esoteric problems, the paradigm forces scientists to investigate some part of nature in detail and depth that would otherwise be unimaginable.
  • While “normal science does not aim at novelties of fact or theory and, when successful finds none, new and unsuspected phenomena are, however, repeatedly uncovered by scientific research.” Discovery for Kuhn begins with awareness of anomaly or recognition that nature has violated the paradigm-induced expectations that govern normal science. Kuhn further argues that normal science makes anomalies appear, because the anomalies appear only against the background provided by the paradigm. Kuhn continues by saying that recognition and acknowledgment of anomalies cause crises that result in the emergence of new paradigms. To Kuhn all scientific crises begin with a blurring of a paradigm and a loosening of the rules of normal science. Kuhn then argues the crises are resolved in one of three ways. Sometimes normal science may prove capable of handling the problem and normal science returns. Other times, the problem persists and is recognized and labeled, but is set aside for a future time when better research tools are available. Or, finally the “crisis may end with the emergence of a new candidate for paradigm and with an ensuing battle over its acceptance.”
  • The “thick ice sheet that melted fast” paradigm emerged after going through all the steps Kuhn describes. Thornbury’s book [1] identifies numerous regional geomorphology problems that were set aside by past regional geomorphology researchers in the hope better research tools would become available. Better research tools have become available, but normal science is using those better research tools to solve a different set of geomorphology problems. The regional geomorphology problems identified by Thornbury still exist and many, if not all of those problems can be resolved when evidence is viewed from the “thick ice sheet that melted fast” paradigm perspective. While the “thick ice sheet that melted fast” paradigm has emerged, it has yet to gain acceptance. Resistance to paradigm change is natural and is to be expected.
  • Kuhn states, “the transfer of allegiance from paradigm to paradigm is a conversion experience that cannot be forced.” Kuhn further argues, “probably the single most prevalent claim advanced by the proponents of a new paradigm is that they can solve the problems that led the old one to a crisis. When it can legitimately be made, this claim is often the most effective one possible.” The Missouri River drainage basin landform origins research project essay series is a claim and demonstration the “thick ice sheet that melted fast” paradigm can solve previously shelved and neglected regional geomorphology problems, including the origin of drainage divides, barbed tributaries, through valleys, elbows of capture, erosional escarpments, and drainage route orientations. The new paradigm is being presented here for use by future regional geomorphology research scientists.
  • Like with any new paradigm being introduced for the first time the Missouri River drainage basin landform origins research project essay interpretations only begin to illustrate the “thick ice sheet that melted fast” regional geomorphology potential. The essay interpretations are based almost entirely on the illustrated topographic map evidence. Use of more detailed topographic maps, mosaics of topographic maps covering larger areas, and introduction of other types of evidence can help researchers flesh out additional paradigm details. Also, future researchers will find ways to significantly improve upon these first attempt interpretations. Hopefully, however, these initial interpretations will provide sufficient guidance to help future geomorphology researchers view evidence from what they will discover to be a very productive and useful regional geomorphology paradigm.
  • The project goal is to address drainage divides between all major Missouri River tributaries and also with all adjacent drainage basins. The project was completed in early 2013 and discussion with other interested scientists is invited either on this website or off site at eric2clausen@gmail.com

References

  1. Thornbury, William D.,1965, Regional Geomorphology of the United States, John Wiley and Sons, New York, 609 pages.
  2. Fenneman, Nevin M., 1931, Physiography of the Western United, McGraw-Hill Book Company, New York, 534 pages.
  3. Geological Society of America, 2009, Stay connected with GSA’s divisions, GSA Today, volume 19, number 11, pages 20-21.
  4. White, W. A., 1972, Deep erosion by continental ice sheets. Geological Society of America Bulletin volume 83, pp. 1037-56.
  5. Sugden, D. E., 1976, A case against deep erosion of shields by ice sheets. Geology volume 4, pp 580-2.
  6. Gravenor, C. P., 1975, Erosion by continental ice sheets. American Journal Science volume 275, pp. 594-604.
  7. Bell, M., and Laine, E.P., 1985, Erosion of the Laurentide Region of North America by glacial and glaciofluvial processes. Quaternary Research volume 23, pp. 154-174.
  8. Kehew, A. E., 1979, Evidence for Late Wisconsin catastrophic flooding in the Souris River area, north central North Dakota, Proceedings North Dakota Academy of Science, volume 33, p 32.
  9. Kuhn, Thomas S., 1962, The Structure of Scientific Revolutions (second edition, enlarged), The University of Chicago Press, 210 pages

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