Two more late Ice Age megafloods discovered
Posted on homepage: 13 July 2012 (GMT+10)
It took 40 years for mainstream geologists to accept the Lake Missoula flood, despite hundreds of pieces of obvious evidence.1 The acceptance forced many geologists to shift from strict uniformitarianism (the reason they rejected the Lake Missoula flood in the first place) to believing in neo-catastrophism—the idea that the earth in rare instances does have huge catastrophes. The meteorite impact hypotheses for the extinction of the dinosaurs2 and Ager’s discovery that some sedimentary units were quickly laid down over hundreds of kilometers3 has reinforced the trend towards neo-catastrophism among mainstream geologists.
Numerous Ice Age megafloods
It is interesting that once the Lake Missoula flood was accepted in the 1960s, numerous other Ice Age megafloods have come to light. Geologists could not comprehend or see any evidence for these megafloods before the possibility entered their minds. Similar to the effect of the Ice Age megaflood controversy, I believe the worldview of mainstream scientists keeps them from seeing the copious evidence for the Genesis Flood in the rocks and fossils.
Some of the megafloods discovered include the Bonneville flood down the Snake River of southern Idaho and southeast Washington, caused by pluvial Lake Bonneville overspilling a low point in southeast Idaho with the top of the lake dropping over 100 m.4 A dammed glacial lake burst in the Altai Mountains of south central Siberia sending a huge flood on the scale of the Lake Missoula flood down the Chuja and Katun Rivers.5 The floor of the eastern English Channel is now believed to have been carved by the catastrophic drainage of a huge lake in the area of the southern North Sea (figure 1).6 Two megafloods have been postulated,7 but, regardless, the flood/s probably severed England from mainline Europe.
Numerous Ice Age megafloods from glacial Lake Agassiz in central Canada have been claimed.8 These floods are believed to have flooded south down the Mississippi River, east through the Great Lakes and Saint Lawrence Seaway, north into Hudson Bay and out into the North Atlantic, and northwest down the Mackenzie River and into the Arctic Ocean.
Glacial Lake Wisconsin was formed along the edge of the Green Bay Lobe of the Laurentide Ice Sheet. As the ice receded, the lake breached catastrophically and flowed down the Wisconsin River.9 This flood overtopped another ridge, creating what is now a water gap. Many water gaps were also formed during the Lake Missoula flood. Both of these floods provide analogs for the thousands of water gaps across the Earth caused by the channelized runoff of the Genesis Flood.10
These are only the well-established Ice Age megafloods. There is also the category of superfloods, around an order of magnitude larger, that supposedly flowed under the ice sheets and out the edge. The study of these superfloods has been pioneered by John Shaw of the University of Alberta in Edmonton, Alberta, Canada. Shaw has published numerous papers linking unique landforms to subglacial floods.11 Superfloods issuing from under the ice are also postulated for southwestern Russia and Antarctica. Subglacial superfloods are not popular with the majority of scientists, but the evidence for them seems substantial.12
Two new megafloods
Recently, at least two new megafloods have been added to the list. The first is actually an old one, but is now considered much larger based on new evidence. This is an outburst megaflood from glacial Lake Agassiz that swept northwest into the Mackenzie River and out into the Arctic Ocean.13
The second megaflood is one of several postulated to have spilled out of the intermontane Cooper River Basin of south central Alaska. As the Alaska Range ice cap in southern Alaska melted, a huge lake, called Lake Atna, was trapped in the Cooper River Basin and overtopped several outlets. One outlet passed westward down the Matanuska Valley through Wasilla and into Cook Inlet.14 The amount of water released is estimated to have been 500–1,400 km3, with a depth over the Wasilla area of 34–70 m, and a flow velocity estimated between 13–57 m/sec. The evidence for the flow of water can be seen from space in a series of long north-south mega-ripple marks.
Did the megaflood down the Mackenzie River cause the Younger Dryas?
The megaflood into the Arctic Ocean from glacial Lake Agassiz (figure 2) is claimed to have caused the Younger Dryas, a cold snap that occurred during deglaciation, when temperatures were warming. The claimed temperature drop of around 10°C, based on oxygen isotope data, occurred mainly in the Northern Hemisphere.
The Younger Dryas has been detected in many climatic records, such as ice cores.15 Although these ice core records have been dated using uniformitarian assumptions, in particular that annual layers can be counted to near the bottom of Greenland ice cores, the Younger Dryas is still represented by a large negative deviation in the oxygen isotope ratio during the time when the oxygen isotopes are strongly increasing during deglaciation.
The major suggestion for how such a megaflood pulse cools the atmosphere is that freshwater floating over denser saltwater stops the North Atlantic thermohaline circulation.16 The thermohaline circulation is part of the large-scale ocean circulation, or meridional overturning of the ocean water, that is driven by ocean density gradients, caused by differences in temperature and salt content. Such a freshwater pulse would result in much more sea ice that would reflect more sunlight back to space and stop evaporation from the capped ocean, thus cooling the atmosphere, especially in the Northern Hemisphere.
However, the origin of the Younger Dryas is still much debated.17 It has been assumed that the pulse of freshwater had to have entered the North Atlantic Ocean by e.g. the St. Lawrence Seaway, but the traces of such a megaflood flowing directly into the North Atlantic have been hard to find.18 So, some researchers think that a pulse into the Arctic Ocean could have made it to the North Atlantic Ocean.19 That is why some researchers are excited about the enhanced megaflood from glacial Lake Agassiz into the Arctic Ocean. But how does the pulse affect the North Atlantic?
There are several problems with the Younger Dryas originating from the freshening of the Arctic Ocean. First, the freshwater pulse may become so diluted moving from the Arctic Ocean into the North Atlantic as to be of no consequence for the thermohaline circulation.
Second, it is assumed that a pulse of freshwater from a megaflood would have floated on the denser seawater and under the sea ice. But the megaflood meltwater pulse would also have been very muddy and possibly dense enough to sink to intermediate depths or to the ocean bottom. In the latter case, the meltwater pulse would have become a turbidity current and dissipated in the deep Arctic Ocean.
The idea of a freshwater pulse capping the North Atlantic Ocean and stopping the North Atlantic thermohaline circulation, although widely believed,20 is still controversial.21 Researchers are finding out that the ocean circulation is driven more by ocean current eddies and wind and not so much by density differences:
“The wind and its spatial structures are drivers of the entire top-to-bottom [ocean] circulation, including that part which many authors regard as buoyancy driven. Oceanic response to wind-driving is generally extremely fast and efficient.”22
Therefore, a pulse of freshwater flowing out into the North Atlantic, either directly through the St Lawrence Seaway or indirectly through the Arctic Ocean, likely would not stop the thermohaline circulation. Besides, one megaflood, even into the North Atlantic, likely would not be significant enough to stop the circulation because of the large size of the North Atlantic Ocean.
Creationist Ice Age implication
All these megafloods reinforce the idea that the Ice Age ice sheets melted catastrophically.23 Furthermore, the creationist Ice Age model has the potential to cause the Younger Dryas cold snap because there was very little sea ice, even in the Arctic Ocean, late in the Ice Age. (It is difficult to freeze the top of seawater, but a less dense cap of freshwater makes it much easier.) So pulses of freshwater floating over the saltwater from many megafloods and the catastrophic melting of the ice in general could have triggered the Younger Dryas.24 The effect would have been most dramatic over the Arctic Ocean. Of course, the Younger Dryas in the creationists scheme did not last on the order of a thousand years, as assumed by uniformitarian scientists, but would have been on the order of tens of years.
- Oard, M.J., The Missoula Flood Controversy and the Genesis Flood, Creation Research Society Books, Chino Valley, AZ, 2004. Return to text.
- Alvarez, L.W., Alvarez, W., Asaro, F. and Michel, H.V., Extraterrestrial cause for the Cretaceous–Tertiary extinction, Science 208:1095–1108, 1980. Return to text.
- Ager, D., The New Catastrophism: The Importance of the Rare Event in Geological History, Cambridge University Press, Cambridge, UK, 1993. Return to text.
- O’Connor, J.E., Hydrology, Hydraulics, and Geomorphology of the Bonneville Flood, GSA Special Paper 2974, Geological Society of America, Boulder, CO, 1993. Return to text.
- Rudoy, A.N., Glacier-dammed lakes and geological work of glacial superfloods in the Late Pleistocene, Southern Siberia, Altai Mountains, Quaternary International 87:119–140, 2002. Return to text.
- Gupta, S., Collier, J.S., Palmer-Felgate, A. and Potter, G., Catastrophic flooding origin of shelf valley systems in the English Channel, Nature 448:342–345, 2007. Return to text.
- Silvestru, E., Wild, wild floods! J. Creation 22(1):12–14, 2008. Return to text.
- Teller, J.T. and Leveringson, D.W., Glacial Lake Agassiz: a 5000 yr history of change and its relationship to the δ18 O record of Greenland, GSA Bulletin 116(5/6):729–742, 2004. Return to text.
- Clayton, J.A. and Knox, J.C., Catastrophic flooding from glacial Lake Wisconsin, Geomorphology 93:384–397, 2008. Return to text.
- Oard, M.J., Flood by Design: Receding Water Shapes the Earth’s Surface, Master Books, Green Forest, AR, pp. 94–109, 2008. Return to text.
- Shaw, J., The meltwater hypothesis for subglacial bedforms, Quaternary International 90:5–22, 2002. Return to text.
- Silvestru, E., Catastrophic subglacial drainage and rapid landscape formation in Canada, with special emphasis on the Niagara Escarpment; in: Proceedings of the Sixth International Conference on Creationism, Snelling, A.A. (Ed.), Creation Science Fellowship and Institute for Creation Research, Pittsburgh, PA, and Dallas, TX, pp. 357–370, 2008. Return to text.
- Murton, J.B., Bateman, M.D., Dallimore, S.R., Teller, J.T. and Yang, Z., Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean, Nature 464:740–743, 2010. Return to text.
- Wiedmer, M., Montgomery, D.R., Gillespie, A.R. and Greenberg, H., Late Quaternary megafloods from glacial Lake Atna, Southcentral Alaska, USA, Quaternary Research 73:413–424, 2010. Return to text.
- Oard, M.J., The Frozen Record: Examining the Ice Core History of the Greenland and Antarctic Ice Sheets, Institute for Creation Research, Dallas, TX, pp. 123–132, 2006. Return to text.
- Broeker, W.S., Thermohaline circulation, the Achilles Heel of our climate system: will manmade CO2 upset the current balance? Science 278:1582–1588, 1997. Return to text.
- Broecker, W.S., Denton, G.H., Edwards, R.L., Cheng, H., Alley, R.B. and Putnam, A.E., Putting the Younger Dryas cold event into context, Quaternary Science Reviews 29:1078–1081, 2010. Return to text.
- De Vernal, A., Hillaire-Marcel, C. and Bilodeau, G., Reduced meltwater outflow from the Laurentide ice margin during the Younger Dryas, Nature 381:774–777, 1996. Return to text.
- Peltier, W.R., Vettoretti, G. and Stastna, M., Atlantic meridional overturning and climate response to Arctic Ocean freshening, Geophysical Research Letters 33:doi:10.1029/2005GL025251, 2006. Return to text.
- Schiermeier, Q., River reveals chilling tracks of ancient flood, Nature 464:657, 2010. Return to text.
- Lozier, M.S., Deconstructing the conveyer belt, Science 328:1507–1511, 2010. Return to text.
- Wunsch, C., Greenland—Antarctic phase relations and millennial time-scale climate fluctuations in the Greenland ice-cores, Quaternary Science Reviews 22:1,641, 2003. Return to text.
- Oard, M.J., Frozen in Time: Woolly Mammoths, the Ice Age, and the Biblical Key to Their Secrets, Master Books, Green Forest, AR, pp. 95–106, 2004. Return to text.
- Goodenow, S., A catastrophic cause for the Younger Dryas, Master’s Thesis, Institute for Creation Research Graduate School, Dallas, TX, 2004. Return to text.