Posted on 01/10/2006 2:47:01 PM PST by blam
Different events. I believe the one out west that carved the Snake River happened after this chill.
The Oldest Dryas was about 18,000 ya, IIRC.
The Younger Dryas was dated about 13,000 - 11,500 ya and de4scribed in Wikipedia as follows:
The prevailing theory holds that the Younger Dryas was caused by a significant reduction or shutdown of the North Atlantic thermohaline circulation in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. This theory does not explain why South America cooled first.
The event described in the article was 8,200 ya but seems to have about the same cause as the Younger Dryas. It would seem that this might be a recurring type of event happening as the glacial ice sheets retreat.
ice age is not a movie just for kids, it's beats the junk science with a stick
I am not a one of the environmental nuts, I know the planet and solar system does whatever it is scheduled to do. Something like an immediate drop of several degrees Centigrade would be awful. I am sure many Canadians wouldn't be happy, nor many of our northern brothers. Heck, they would all come down here and we wouldn't be happy. Disaster.
There was once on Discovery a talk about some eggheads who went to some lake in Canada and took core samples of the sediments.
From decoding the pollens and sizes of the sediments they were able to determine how long it took one of the ice age periods to go from temperate climate to full-bore ice age glaciation.
Drum roll..............
90 years.
Less than a blink of an eye in geologic terms.
I would very happy - think how long the ski season would be, for one; how nice Phoenix and the Havasu Lakes would be with a more moderate summer; as well as the entire beautiful, but currently too hot Mexican Desert. I think there'd be plenty of room for all the Canadians that wanted to come.
Pat's circuit breaker tripped last week; it'll reset itself in a month or so.
You are referring to Glacial Lake Missoula. It was a tiny fraction of the size of the lake referred to in the article. I've seen an artist's rendering of this lake, and it covered most of Saskatchewan, Manitoba, North Dakota, and parts of Alberta, Minnesota, and South Dakota. It was huge.
I knew about this years ago. The National Academy of Sciences is just now finding out?
Prior to the Pleistocene glaciations, much of what is now the Missippi drainage flowed North into the area of what now is Hudson's Bay. This includes the Tennessee, Kentucky, Ohio, and Monongahela Rivers, and their adjacent drainages. The glaciers stopped this natural pattern and turned the rivers around to flow south.
Ughh - which way to the UN conference on climate change!
That's funny - thanks!
You're thinking of Lake Bonneville in Utah, of which the Great Salt Lake is a tiny remnant. Bonneville would still be there today (covering much of Utah) except for one pesky volcano. That volcano erupted, redirecting the Bear River into the lake (it had previously flowed elsewhere). The influx of water caused Bonneville to grow until it finally found a low spot at the Red Rock Pass in Idaho. The pass didn't exist before the water overtopped it, but was carved in a matter of hours as the water scoured it to the bedrock. Bonneville, which had extended from Idaho into central Utah, emptied in two days.
No doubt it was global in a sense, but there were regions that were fairly comfortable. Even in the US south of the ice sheet there would be summer or at least some fairly decent days. The interior of Alaska was pretty much the same as it is now, although the sabertooth tigers and mammoths are gone. Large regions might be on average a little cooler but that might not be a bad thing such as in iraq and India. Was the Arctic Ocean iced over at all? There are winters in upstate New York that don't seem far removed from the Ice Age. It kind of makes one wonder if the Ice Age is really such a big deal.
Catastrophic Flooding from Ancient Lake May Have Triggered Cold Period
Imagine a lake three times the size of the present-day Lake Ontario breaking through a dam and flooding down the Hudson River Valley past New York City and into the North Atlantic. The results would be catastrophic if it happened today, but it did happen some 13,400 years ago during the retreat of glaciers over North America and may have triggered a brief cooling known as the Intra-Allerod Cold Period.
Assistant Scientist Jeffrey Donnelly of the Woods Hole Oceanographic Institution presented the findings at the American Geophysical Union’s fall meeting in San Francisco today. Donnelly and colleagues analyzed data from sediment cores, walrus fossils and pollen to precisely date the discharge from Glacial Lake Iroquois down the Hudson River Valley at 13,350 years ago. The flood waters broke through a spot of land where the Verazanno Narrows Bridge now stands to reach the North Atlantic.
The discharge of glacial freshwater into the North Atlantic has long been thought to drive fluctuations in past climate because the huge volume of freshwater would alter thermohaline circulation in the ocean. Directly linking discharge events with individual climatic changes has been difficult because of the challenges in pinpointing the location, timing and amount of the discharge.
The Intra-Allerod Cold Period lasted only about 150 years and occurred just before the Younger Dryas, a sudden cold climate period lasting some 1,200 years and ending about 11,000 years ago. Many scientists believe the Younger Dryas was caused by the shutdown of the Gulf Stream in response to a sudden influx of fresh water from deglaciation in North America. Global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the North Atlantic Ocean.
The team compared their evidence for the massive flood down the Hudson Valley with data from sediment cores taken from the Cariaco Basin off Venezuela in the Caribbean, which show a slowing of thermohaline circulation and heat transport into the North Atlantic at that same time.
Donnelly and his colleagues were able to determine the timing of this event by analyzing data from sediment cores from the Hudson River Valley and the continental shelf. Sediment samples collected near the Tappan Zee Bridge indicate that ocean water flooded the lower Hudson Valley just after the flood event occurred. Pollen data from the first marine sediments deposited near the Holland Tunnel correlate with those from radiocarbon-dated sediments from nearby Sutherland Pond in New York and provide further constraint on the timing of the flood. Walrus remains recovered from gigantic sediment lobes deposited offshore during the flood were carbon dated to further pinpoint a precise time period.
Large rocks the size of Volkswagens, also associated with these sediment lobes, have been photographed on the outer continental shelf off the mouth of the Hudson River, where sediments normally are the size of grains of sand or smaller. Donnelly says the large rocks most likely came from the melting glacier and were carried down to the Atlantic in the floodwaters.
Glacial Lake Iroquois, in the same location and about three times the size as modern day Lake Ontario, was formed as the Laurentide Ice Sheet receded from its maximum extent along southern Long Island, New York, and northern New Jersey to southern Canada from about 21,000 to 13,000 years ago. Several other glacial lakes, Glacial Lake Albany and Glacial Lake Vermont, existed for several thousand years and deposited thick layers of silt and clay in the Hudson River Valley and Champlain Lowlands.
Donnelly says a dam north of the Adirondack Mountains in upstate New York holding back the ancient lake collapsed, allowing lake water to drain into the Hudson River Valley and the North Atlantic, dropping the level of Glacial Lake Iroquois some 120 meters (about 400 feet). Following the collapse of Glacial Lake Iroquois, another lake, Glacial Lake Candona, formed in the Ontario, Saint Lawrence and Champlain Lowlands, controlled in level by a sill or rock dam near Fort Ann, Vermont.
Lake Candona existed only about 100 to 200 years before it drained to the Atlantic when the ice sheet blocking the St. Lawrence Valley collapsed. Following the drainage of Lake Candona, seawater invaded the St. Lawrence and Champlain Lowlands and formed the Laurentian Seaway and the Champlain Sea. Glacial Lake Candona dropped about 40 meters (125 feet) as it drained into the North Atlantic via the Saint Lawrence River Valley. This opening of the St. Lawrence Valley as a conduit for glacial meltwater about 13,000 years ago likely played a role in causing the onset of the Younger Dryas cold interval.
The team will publish the results of the complete study in the February 2005 issue of the journal Geology. Donnelly’s research was funded by the Postdoctoral Scholar Program, The John E. and Anne W. Sawyer Endowed Fund, The J. Lamar Worzel Assistant Scientist Fund, and the Ocean and Climate Change Institute at the Woods Hole Oceanographic Institution.
Woods Hole Oceanographic Institution (WHOI) is a private, independent marine research and engineering and higher education organization located in Falmouth, MA. Its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. Established in 1930 on a recommendation from the National Academy of Sciences, the Institution operates the US National Deep Submergence Facility that includes the deep-diving submersible Alvin, a fleet of global ranging ships and smaller coastal vessels, and a variety of other tethered and autonomous underwater vehicles. WHOI is organized into five departments, interdisciplinary institutes and a marine policy center, and conducts a joint graduate education program with the Massachusetts Institute of Technology.
More information: www.whoi.edu/media/2004_donnelly_lake_iroquois.html
www.whoi.edu
The Wisconsin Dells were formed by a developer who had a vision to turn the entire area into a year round Indoor Water Park.
You have paraphrased what I said. The issue is whether there is a net accumulation after a winter/summer cycle. If the net is positive over the long term, you have an ice age.
... even worse, a number of SUVs have been discovered in the prehistoric runoff...
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