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64-597: These floods have been researched since the 1920s. During the last deglaciation that followed the end of the Last Glacial Maximum , geologists estimate that a cycle of flooding and reformation of the lake lasted an average of 55 years and that the floods occurred several times over the 2,000 years between 15,000 and 13,000 years ago. U.S. Geological Survey hydrologist Jim O'Connor and Spain 's Museo Nacional de Ciencias Naturales scientist Gerardo Benito have found evidence of at least twenty-five massive floods,

128-593: A catastrophic explanation of the geology, ran against the prevailing view of uniformitarianism , and Bretz's views were initially disregarded. The Geological Society of Washington, D.C , invited the young Bretz to present his previously published research at a January 12, 1927, meeting where several other geologists presented competing theories. Another geologist at the meeting, J.T. Pardee , had worked with Bretz and had evidence of an ancient glacial lake that lent credence to Bretz's theories. Bretz defended his theories, which kicked off an acrimonious 40-year debate over

192-486: A biological methane sink for the subglacial ecosystem, and the region was at least during the sample time, a source of atmospheric methane . Based on dissolved methane in water samples, Greenland may represent a significant global methane source, and may contribute significantly more due to ongoing deglaciation. A study in 2016 concluded based on past evidence, that below Greenland's and Antarctica's ice sheet may exist methane clathrates . At every scale, climate influences

256-515: A comment on the Komatsu analysis, Brian Atwater and colleagues observed substantial evidence for multiple large floods, including mud cracks and animal burrows in lower layers, which were filled by sediment from later floods. Further, evidence for multiple flood flows up sidearms of Glacial Lake Columbia spread over many centuries has been found. They also pointed out that the discharge point from Lake Columbia varied with time, originally flowing across

320-564: A drastic negative impact on the global extent and stability of the cryosphere. On the millennial time scales of Pleistocene glacial and interglacial cycles, the pacemaker of glaciation onset and melting are changes in orbital parameters termed the Milankovitch cycles . Specifically, low summer insolation in the northern hemisphere permits growth of ice sheets, while high summer insolation causes more ablation than winter snow accumulation. Human activities promoting climate change , notably

384-555: A global scale, and Earth has been experiencing a relatively warm interglacial period marked by only high-altitude alpine glaciers at most latitudes with larger ice sheet and sea ice at the poles. However, since the onset of the Industrial Revolution , human activity has contributed to a rapid increase in the speed and scope of deglaciation globally. Research published in 2014 suggests that below Greenland 's Russell Glacier 's ice sheet, methanotrophs could serve as

448-617: A large enough scale, an increase in volcanic activity provides a positive feedback to the process of deglaciation as a result CO 2 and methane released from volcanos. Periods of deglaciation are also caused in part by oceanic processes. For example, interruptions of the usual deep cold water circulation and penetration depths in the North Atlantic have feedbacks that promote further glacial retreat. Deglaciation influences sea level because water previously held on land in solid form turns into liquid water and eventually drains into

512-674: A newly published topographic map of the Potholes Cataract . Bretz coined the term Channeled Scablands in 1923 to refer to the area near the Grand Coulee , where massive erosion had cut through basalt deposits. Bretz published a paper in 1923 arguing that the Channeled Scablands in Eastern Washington were caused by massive flooding in the distant past. Bretz's view, which was seen as arguing for

576-675: Is designated a National Wild and Scenic River. The river is not afforded any protection in British Columbia. This has been the subject of 33 years of dispute between the United States and Canada. In 1988 the International Joint Commission , ruled that a proposed open pit coal mine would violate the 1909 Boundary Waters Treaty. Energy development once threatened the North Fork, which was deemed

640-752: The Clark Fork . The river is part of the Columbia River drainage basin, as the Clark Fork is a tributary of the Pend Oreille River , a Columbia River tributary. With a drainage basin extending over 8,795 square miles (22,780 km ) and an average discharge of 11,380 cubic feet per second (322 m /s), the Flathead is the largest tributary of the Clark Fork and constitutes over half of its flow. The Flathead River rises in forks in

704-665: The Hanford formation , has documented the presence of Middle and Early Pleistocene Missoula flood deposits within the Othello Channels, Columbia River Gorge, Channeled Scabland , Quincy Basin, Pasco Basin, and the Walla Walla Valley . Based on the presence of multiple interglacial calcretes interbedded with flood deposits, magnetostratigraphy , optically stimulated luminescence dating, and unconformity truncated clastic dikes , it has been estimated that

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768-600: The Laurentide Ice Sheet spread over large areas of northern North America, with over 5,000,000 square miles of coverage. The Laurentide ice sheet was 10,000 feet deep in some areas, and reached as far south as 37°N. Mapped extent of the Laurentide Ice Sheet during deglaciation has been prepared by Dyke et al. Cycles of deglaciation are driven by various factors, with the main driver being changes in incoming summer solar radiation, or insolation, in

832-651: The Southern Ocean contain long-sequestered stores of CO 2 which are now being emitted into the atmosphere and are continuing to impact glacial dynamics. The principle of isostasy applies directly to the process of deglaciation, especially post-glacial rebound , which is one of main mechanisms through which isostasy is observed and studied. Post-glacial rebound refers to the increase in tectonic uplift activity immediately following glacial retreat. Increased rates and abundance of volcanic activity have been found in regions experiencing post-glacial rebound. If on

896-469: The Spokane Valley – Rathdrum Prairie immediately downstream of Glacial Lake Missoula, for which several previous estimates had placed the maximum discharge of 17 × 10m/s and the total amount of water discharged equal to the maximum estimated volume of Lake Missoula (2184 km). Neglecting erosion effects, their simulated water flow was based on modern-day topography. Their major findings were that

960-614: The Swan River joins. Near Polson the river leaves the natural basin of Flathead Lake, but first passes through Seli’š Ksanka Qlispe’ Dam (formerly Kerr Dam), which raised Flathead Lake 's natural level by 10 feet (3.0 m). After flowing through the dam the river turns south and meanders through the Flathead Valley west of the Mission Mountains , and at Dixon it is joined by the small Jocko River . At

1024-553: The Whitefish Range and Swan Range via Bad Rock Canyon . All of the headwaters forks are entirely or in part designated National Wild and Scenic Rivers . After the river leaves the canyon it flows into the broad Flathead Valley and arcs southwest, passing Columbia Falls and Kalispell , before it is joined by the Stillwater River and its Whitefish River tributary, and then empties into Flathead Lake , where

1088-507: The "wildest river in the continental United States" by The New York Times in 2004. On February 21, 2008, BP announced to drop plans to obtain drilling rights for coalbed methane extraction in the river's headwaters. The Cline Mining Corporation still intended to start a mountaintop-removal coal mining project. On February 9, 2010, the British Columbia government announced that it would not permit mining, oil and gas development and coalbed gas extraction in British Columbia's portion of

1152-483: The Antarctic melted. As a consequence, sea levels rose roughly 120 metres. These processes did not occur steadily, and they also did not occur at the same time. The process of deglaciation reflects a lack of balance between existing glacial extent and climatic conditions. As a result of net negative mass balance over time, glaciers and ice sheets retreat. The repeated periods of increased and decreased extent of

1216-588: The Channeled Scabland landforms were formed mainly by multiple periodic floods or by a single grand-scale cataclysmic flood from late Pleistocene Glacial Lake Missoula or an unidentified Canadian source continued through 1999. Shaw's team of geologists reviewed the sedimentary sequences of the Touchet beds and concluded that the sequences do not automatically imply multiple floods separated by decades or centuries. Rather, they proposed that sedimentation in

1280-481: The Columbia Gorge would be expected to produce higher flow resistance and correspondingly higher floods. The dating for Waitt's proposed separation of layers into sequential floods has been supported by subsequent paleomagnetism studies, which support a 30–40 year interval between depositions of Mount St. Helens' ash, and hence flood events, but do not preclude an up to 60-year interval. Offshore deposits on

1344-541: The Columbia River gorge, it backed up again at the 1 mile (1.6 km) wide narrows near Kalama, Washington . Some temporary lakes rose to an elevation of more than 400 ft (120 m), flooding the Willamette Valley to Eugene, Oregon and beyond. Iceberg-rafted glacial erratics and erosion features are evidence of these events. Lake-bottom sediments deposited by the floods have contributed to

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1408-797: The Flathead – from Schaffer creek to its confluence with the Flathead River; and the Flathead River – to its confluence with the Clark Fork River, are designated. It is part of the National Wild and Scenic Rivers System . Reaches designated wild and scenic include the entire North Fork south of the Canada–US border, the entire Middle Fork, and the South Fork above Hungry Horse Reservoir. The North Fork Flathead River in Montana

1472-624: The Glacial Lake Missoula basin resulted from jökulhlaups draining into Lake Missoula from British Columbia to the north. Further, Shaw's team proposed the scabland flooding might have partially originated from an enormous subglacial reservoir that extended over much of central British Columbia, particularly including the Rocky Mountain Trench , which may have discharged by several paths, including one through Lake Missoula. This discharge, if occurring concurrently with

1536-620: The Jocko River confluence it turns west, and a few miles after flows into the Clark Fork near Paradise . David Thompson (explorer) explored the area in 1807. Fur traders employed by the North West Company and Hudson's Bay Company entered the Flathead Valley in the early 19th century. Trading posts were established north of Flathead Lake. The 1846 settlement of the Oregon Boundary Dispute established

1600-553: The LGM compared to today, as there was open forest, where today we see desert and steppe. In the United States, the general variation of vegetation implies an overall fall in temperatures of (at minimum 5 °C), a shift of the westerly storm tracks to the south, and a very steep latitudinal temperature gradient. Several landforms visible today are distinctive of the powerful erosional forces at play during, or immediately after, deglaciation. The distribution of such landforms helps to inform

1664-467: The Laurentide ice sheet presented a positive surface mass balance during almost the entirety of its deglaciation, which indicates that the loss of mass throughout its deglaciation was more than likely due to dynamic discharge. It was not until the early Holocene when the surface mass balance switched to become negative. This change to a negative surface mass balance suggested that surface ablation became

1728-664: The Northern Hemisphere. But, as not all of the rises in insolation throughout time caused deglaciation, to the current ice volumes that we witness today. This leads to a different conclusion, one that suggests that there is a possible climatic threshold, in terms of ice sheets retreating, and eventually disappearing. As Laurentide was the largest mass ice sheet in the Northern Hemisphere, much study has been conducted regarding its disappearance, unloading energy balance models, atmosphere-ocean general circulation models, and surface energy balance models. These studies concluded that

1792-708: The Rocky Mountains of northwestern Montana. The largest tributary is the North Fork , which runs from the Canadian province of British Columbia southwards. The North Fork is sometimes considered the main stem of the Flathead River. Near West Glacier the North Fork combines with the Middle Fork to form the main Flathead River. The river then flows westwards to join the South Fork and cuts between

1856-699: The Waterville Plateau into Moses Coulee, but later, when the Okanagan lobe blocked that route, eroding the Grand Coulee to discharge there as a substantially lower outlet. The Komatsu analysis does not evaluate the impact of the considerable erosion observed in this basin during the flood or floods. However, the assumption that flood hydraulics can be modeled using modern-day topography is an area that warrants further consideration. Earlier narrower constrictions at places such as Wallula Gap and through

1920-526: The agricultural richness of the Willamette and Columbia Valleys. Glacial deposits overlaid with centuries of windblown sediments ( loess ) have scattered steep, southerly sloping dunes throughout the Columbia Valley, ideal conditions for orchard and vineyard development at higher latitudes. After analysis and controversy, geologists now believe that there were 40 or more separate floods, although

1984-418: The alteration of ice sheets, to the concentration of greenhouse gases fluctuating, and many other feedbacks that resulted in distinct responses, both globally and regionally. Not only were ice sheets and greenhouse gases experiencing alteration, but also additionally to this, there was sudden climate change , and many occurrences of fast, and sizeable rising of sea level. The melting of the ice sheets, along with

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2048-678: The bed of the Pacific at the mouth of the Columbia River include 120 meters of material deposited over a several thousand-year period corresponding to multiple scabland floods seen in the Touchet Beds. Based on Waitt's identification of 40 floods, this would give an average separation between floods of 50 years. Deglaciation Deglaciation is the transition from full glacial conditions during ice ages , to warm interglacials , characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to

2112-415: The border with British North America and that the Flathead Valley was firmly American. The first settlers began arriving in the 1860s. Irrigation agriculture began in the 1880s. The river was affected by the 2022 Montana floods . The river is a Class I river in Montana for purposes of recreational access. The South fork of the Flathead, from Youngs Creek to Hungry Horse reservoir ; Middle fork of

2176-473: The breach of the Lake Missoula ice dam, would have provided significantly larger volumes of water. Further, Shaw and the team proposed that the rhythmic Touchet beds result from multiple pulses or surges within a larger flood. In 2000, a team led by Komatsu simulated the floods numerically with a 3-dimensional hydraulic model. They based the Glacial Lake Missoula discharge rate on the rate predicted for

2240-564: The calculated water depth in each flooded location except for the Spokane Valley–Rathdrum Prairie was shallower than the field evidence showed. For example, their calculated water depth at the Pasco Basin–Wallula Gap transition zone is about 190 m, significantly less than the 280–300 m flood depth indicated by high-water marks. They concluded that a flood of ~10m/s could not have made the observed high-water marks. In

2304-744: The catastrophic floods, which he called the Spokane floods , in the 1920s. He was researching the Channeled Scablands in Eastern Washington , the Columbia Gorge , and the Willamette Valley of Oregon . Beginning In the summer of 1922, Bretz conducted field research on the Columbia River Plateau for the next seven years. He had been interested in unusual erosion features in the area since 1910 after seeing

2368-522: The condition of snow and ice on Earth's surface. In colder periods massive ice sheets may extend toward the Equator , while in periods warmer than today, the Earth may be completely free of ice. A significant, empirically demonstrated, positive relationship exists between the surface temperature and concentration of Greenhouse gases such as CO 2 in the atmosphere . The higher concentration, in turn, has

2432-404: The cracks, generating more heat, allowing even more water to flow through the cracks. This feedback cycle eventually weakened the ice dam so much that it could no longer support the pressure of the water behind it. It failed catastrophically. This process is known as a glacial lake outburst flood , and there is evidence that many such events occurred in the distant past. As the water emerged from

2496-483: The driver that resulted in the loss of mass of ice in the Laurentide ice sheet. It is concluded then that the Laurentide ice sheet only began to exhibit behaviours and patterns of deglaciation after radiative forcing and summer temperatures began to rise at the beginning of the Holocene. When the Laurentide ice sheet progressed through the process of deglaciation, it created many new landforms and had various effects of

2560-403: The east was populated by cold-tolerant conifer forests, while the southeast and northwest of the United States sustained open forests in locations that have closed forests today, which suggests that during the LGM temperatures were cooler and overall conditions were much drier than those that we experience today. There is also indication that the southwest of the United States was much wetter during

2624-545: The end of the Last Glacial Maximum to the early Holocene (ca. 19k-11k years ago), shows changes in greenhouse gas concentrations and of the Atlantic meridional overturning circulation (AMOC), when sea-level rose by 80 meters. Additionally, the last deglaciation is marked by three abrupt CO 2 pulses, and records of volcanic eruptions show that subaerial volcanism increased globally by two to six times above background levels between 12 ka and 7 ka. Between roughly 19ka,

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2688-478: The end of the Last Glacial Maximum (or LGM) to 11ka, which was the early Holocene, the climate system experienced drastic transformation. Much of this change was occurring at an astonishing rate, as the earth was dealing with the end of the last ice age. Changes in insolation was the principal reason for this drastic global change in climate, as this was linked with several other changes globally, from

2752-405: The exact source of the water is still being debated. The peak flow of the floods is estimated to be 27 cubic kilometers per hour (6.5 cubic miles per hour). The maximum flow speed approached 36 meters/second (130 km/h or 80 mph). Up to 1.9×10 joules of potential energy were released by each flood (the equivalent of 4,500 megatons of TNT ). For comparison, this is 90 times more powerful than

2816-517: The extensive use of fossil fuels over the last 150 years and the resulting increase in atmospheric CO 2 concentrations, are the principal cause of the more rapid retreat of alpine glaciers and continental ice sheets all across the world. For example, the West Antarctic Ice Sheet has receded significantly, and is now contributing to a positive feedback loop that threatens further deglaciation or collapse. Newly exposed areas of

2880-466: The global cryosphere (as deduced from observations of ice and rock cores, surface landforms, sub-surface geologic structures, the fossil record, and other methods of dating) reflect the cyclical nature of global and regional glaciology measured by ice ages and smaller periods known as glacials and interglacials . Since the end of the Last glacial period about 12,000 years ago, ice sheets have retreated on

2944-539: The greatest density, and most salt content during the LGM. The discharge of such sequestered carbon was perhaps a direct outcome of the deep Southern Ocean overturning, driven by heightened wind-driven upwelling, and sea-ice retreat, which are directly correlated to the warming of the Antarctic, and also coinciding with the cold events, the Oldest and Younger Dryas, in the north. Throughout the LGM in North America,

3008-427: The ice bergs were split and shed (calved) off. Large lakes became prevalent, but so did smaller, shallower, relatively short-lived lakes. This appearance and disappearance of small, shallow lakes influenced much of the plant growth, spread and diversity that we see today. The lakes acted as barriers to plant migration, but when these lakes drained, the plants could migrate and spread very efficiently. The period between

3072-473: The land. First and foremost, as huge glaciers melt, there is a consequently large volume of meltwater. The volumes of meltwater created many features, including proglacial freshwater lakes, which can be sizable. Not only was there meltwater that formed lakes, there were also storms that blew over the inland freshwater. These storms created waves strong enough to erode the ice shores. Once ice cliffs were exposed, due to rising sea levels and erosion caused by waves,

3136-559: The largest discharging about 10 cubic kilometers per hour (2.7 million m³/s, 13 times that of the Amazon River ). Alternate estimates for the peak flow rate of the largest flood range up to 17 cubic kilometers per hour. The maximum flow speed approached 36 meters/second (130 km/h or 80 mph). Within the Columbia River drainage basin , detailed investigation of the Missoula floods' glaciofluvial deposits , informally known as

3200-472: The largest of the boulders moved by the flood. He estimated the water flow was 9 cubic miles per hour (38 km/h), more than the combined flow of every river in the world. More recent estimates place the flow rate at ten times the flow of all current rivers combined. The Missoula floods have also been referred to as the Bretz floods in honor of Bretz. As the depth of the water in Lake Missoula increased,

3264-442: The last 100 years has been accelerating as a result of climate change , partly brought on by anthropogenic changes to greenhouse gases . The previous deglaciation took place from approximately 22  ka until 11.5 ka. This occurred when there was an annual mean atmospheric temperature on the earth that increased by roughly 5 °C, which was also accompanied by regional high-latitude warming that exceeded 10 °C. This

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3328-433: The most powerful nuclear weapon ever detonated, the 50-megaton " Tsar Bomba ". The cumulative effect of the floods was to excavate 210 cubic kilometres (50 cu mi) of loess, sediment, and basalt from the Channeled Scablands of eastern Washington and to transport it downstream. The multiple flood hypothesis was first proposed by R.B. Waitt Jr. in 1980. Waitt argued for a sequence of 40 or more floods. Waitt's proposal

3392-488: The ocean. The recent period of intense deglaciation has resulted in an average global sea level rise of 1.7 mm/year for the entire 20th century, and 3.2 mm/year over the past two decades, a very rapid increase. The physical mechanisms by which deglaciation occurs include melting , evaporation , sublimation , calving , and aeolian processes such as wind scouring. Throughout the Pleistocene Epoch,

3456-662: The oldest of the Pleistocene Missoula floods happened before 1.5 million years ago. Because of the fragmentary nature of older glaciofluvial deposits, which have been largely removed by subsequent Missoula floods, within the Hanford formation, the exact number of older Missoula floods, which are known as ancient cataclysmic floods , that occurred during the Pleistocene cannot be estimated with any confidence. Geologist J Harlen Bretz first recognized evidence of

3520-580: The origin of the Scablands. Both Pardee and Bretz continued their research over the next 30 years, collecting and analyzing evidence that led them to identify Lake Missoula as the source of the Spokane flood and creator of the channeled scablands. After Pardee studied the canyon of the Flathead River , he estimated that flood waters above 45 miles per hour (72 km/h) would be required to roll

3584-480: The period of Deglaciation. During the Last Glacial Maximum (LGM), there were apparent low atmospheric concentration of Carbon Dioxide (CO 2 ), which was believed to be as a result of larger containment of carbon in the deep ocean, via the process of stratification within the Southern Ocean. These Southern Ocean deep waters contained the least δ13C, which consequently resulted in them being the location with

3648-409: The pressure at the bottom of the ice dam increased enough to lower the freezing point of water below the temperature of the ice forming the dam. This allowed liquid water to seep into minuscule cracks present in the ice dam. Over a period of time, the friction from water flowing through these cracks generated enough heat to melt the ice walls and enlarge the cracks. This allowed more water to flow through

3712-467: The retreat of a glacier , an ice sheet or frozen surface layer, and the resulting exposure of the Earth 's surface. The decline of the cryosphere due to ablation can occur on any scale from global to localized to a particular glacier. After the Last Glacial Maximum (ca. 21,000 years ago), the last deglaciation begun, which lasted until the early Holocene . Around much of Earth, deglaciation during

3776-445: The rising sea levels did not happen until after 11ka. Nonetheless, the globe had arrived at its present interglacial period, where climate is comparatively constant and stable, and greenhouse gas concentrations exhibit near pre-industrial levels. This data is all available due to studies and information gathered from proxy records, both from the terrestrial and ocean, which illustrates overall global patterns of changes in climate whilst in

3840-504: The successive geomorphic processes after exposure due to deglaciation: Flathead River The Flathead River ( Salish : člq̓etkʷ ntx̣ʷetkʷ , ntx̣ʷe , Kutenai : kananmituk ), in the northwestern part of the U.S. state of Montana , originates in the Canadian Rockies to the north of Glacier National Park and flows southwest into Flathead Lake , then after a journey of 158 miles (254 km), empties into

3904-425: The top of the Touchet beds. The two layers of volcanic ash are separated by 1–10 centimetres (0.4–3.9 in) of airborne nonvolcanic silt. The tephra is Mount St. Helens ash that fell in Eastern Washington. By analogy, since there were 40 layers with comparable characteristics at Burlingame Canyon, Waitt argued they all could be considered to have similar separation in deposition time. The controversy about whether

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3968-435: The understanding of the glacial dynamics and geologic periods of the past. Studying exposed landforms can also inform the understanding of the present and near future as glaciers all over the world retreat in the current period of climate change. In general, recently deglacialized landscapes are inherently unstable and will tend to move towards an equilibrium. A sampling of common landforms caused by deglaciation, or caused by

4032-457: Was also followed by noteworthy deep-sea and tropical-sea warming, of about 1–2 °C (deep-sea) and 2–4 °C (tropical sea). Not only did this warming occur, but the global hydrological budget also experienced noticeable changes and regional precipitation patterns changed. As a result of all of this, the world's main ice sheets, including the ones located in Eurasia, North America and parts of

4096-630: Was based mainly on analysis from glacial lake bottom deposits in Ninemile Creek and the flood deposits in Burlingame Canyon. His most compelling argument for separate floods was that the Touchet bed deposits from two successive floods were found to be separated by two layers of volcanic ash ( tephra ), with the ash separated by a fine layer of windblown dust deposits, located in a thin layer between sediment layers ten rhythmites below

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