Hi Sterling, all - A brief summary of the end of the last ice age, which is set out in depth in Man and Impact in the Americas:
1)Earlier there are warm currents off the west coast of today's Canada. The Lenape were hunting sea turtle there. These warm currents resulted in snow in today's Canada, snow which reflected the Sun's heat back into space, and the Earth got colder. 2)An impact created the Alaskan and Siberian mucks, and changed the currents in the North Pacific. Colder water now came down from further north, cooling the current off the coast of Canada. Less snow on Canada, more sunlight absorbed, the Earth warmed. This is pretty much what the physical evidence shows, and pretty much what the peoples remembered. I can't speak beyond that: 10,000 years ago. What I can say about the earlier ice ages is that you have to consider that the land which bounded those early currents may have changed. Finally, mt DNA shows the Iroquoian and Algonquin peoples crossed Beringia earlier. Beringia was not there later. All this (in detail) and much much more in "Man and Impact in the Americas", and list members can contact me off list for the special deal for a signed copy. I hope those who obtained their copies in Tucson are enjoying them, and I hope I will be able to write a little more about the peoples and meteorites soon, having covered the peoples and impacts in the book. But then hell, I still need to write my Tucson thank you note to everyone. good hunting, Ed --- "Sterling K. Webb" <[EMAIL PROTECTED]> wrote: > Hi, list, and E.P. > > who said: > > The "present ice age" is not going to return... > [due to] > > a massive impact at the end of the last ice age > [which > > altered currents]... > > The problem with this theory is that the current > mild > spell (which is NOT the "end" of the ice age) is > mediated > by warm midlevel currents (which do not seem to need > an extraordinary explanation). Full glaciation is > the > result of the absence of these currents. If impacts > are > involved in any way (and they may be), they would > produce > coolings (and help ice ages) rather than preventing > or > ending them (or, more correctly, making them > milder). > > The planet has long eons during which natural > ice > does not accumulate or persist more than momentarily > anywhere on the planet at any time of the year. > Ever. > Often this "greenhouse" age lasts for many 10's or > even > 100's of millions of years. During these times, the > ocean > bottom is anaerobic because the oceans do not > circulate, > because their bottom layers are the warmest level of > the > oceans, being highly saline. The temperature > differential > from equator to pole is much less than we are > accustomed > to, and the planet as a whole is much warmer than > the > maddest dreams of "global warmists." > > In an "Ice Age," the oceans circulate in short > time > scales (<1000 years), the bottom waters are the > coldest > layers of the ocean, the sediments are aerobic. The > temperature differential from equator to pole is, > well, > pack an extra sweater if you visit Antarctica. There > are > substantial portions of the planet where ice can be > found > at any time of the year. If this sounds oddly > familiar, > this is because this is the familiar world which we > presently live in. This (look around you) is what an > ice age is. This is an Ice Age, nor are we "out" of > it. > > How'd it get that way? > > About 15 mya (million years ago), a serious > cooling > trend began. East Antarctica acquired the beginnings > of > its ice sheet 14 mya, the first ice in Antarctica in > many ten's > of millions of years. The earliest glaciers in > Alaska show > up 9 mya. West Antarctica started its ice sheet 6.5 > mya. > The first South American glaciers appear 5.5 mya. > Due to > the uptake of water by ice, sealevels declined > during > this time. > > At 3.25 mya, cyclical glaciation world-wide > (what most > folks call "ice-ages") began. Sealevels dropped > sharply, > and cooling became more intense. At 2.4 to 2.2 mya, > the > cooling trend steepened again. Another outcome of > The Ice is global declines in the water content of > the > atmosphere (the cold trap), and world-wide droughts > result after about 2.0 to 1.8 mya. > > About 800,000 years ago (Australasian "tektite" > impact?), the cooling trend steepened more > drastically. > By 700,000 years ago, the North Polar Sea Ice > persisted > through the summer, thus becoming "permanent" (as if > there were such a thing). > > We can see more "detail" in the last 128,000 > years, > of course, and it presents a fascinating picture: > 128,000 to 115,000 ya (years ago) was a long > "interglacial" or warm spell like today, one of the > longest warm spells. It was very slightly warmer > that it is today, which is the horrible state all > the > global warmists all fear, 2 to 4 degrees warmer than > today. However, it was still a full blown ice age > with > all the ice age markers present: ice caps, glaciers, > year-round sea ice, and so forth. > At 115,000 ya, there was a "false ice age." > There's > another "false" ice age at 95,000 ya. A "false" ice > age > is a sudden sharp drop into extreme glacial > conditions > that doesn't last, but "fails" after a few (2? 4? > 6?) thousand > years instead of persisting for ten's of thousands > of years > like a "real" ice age. > Because it can be shown that "false" ice ages go > to > full glaciation conditions in less than a century, > perhaps > less than a decade, most likely they are the result > of > impacts. These impacts cannot be identified with any > impact structures, so the suspects are: oceanic > impact, > shower of cometary objects, passage through an > interstellar dust cloud, or anything else that would > obscure radiant input. > But at 73,000 ya, there's a very severe and > sharp drop > in temperatures, followed by a long ice age with > short, > weak warm spells; it's easier to just point out them > in > the record. > Ice starts at 72,000 ya. > Ice maximum at 62,000 ya > Very short warm spell at 58,000 ya, with weak > warm > spells at 52,000 to 47,000 ya. Short mild spells > between > 40,000 ya and 30,000 ya, all with more glaciation > between > them. > Then, at 28,000 ya another very severe and sharp > drop > like the one in 73,000. This is the ice age that > just "ended" > 10,600 years ago. It didn't "end," of course. We're > just > having another interglacial. Again. Nice, but they > don't last. > > "Ended" is a total misnomer. Do you see any > natural ice > anywhere on this planet? If the answer is "yes," > then it's an > ICE AGE. 18,000 ya, the French Riviera was > permafrost tundra > and the dominant fauna there were reindeer. This > peak glaciation > ended as they all do: repeated weak warm spells that > fail, > with re-cooling, until the warmth finally > successfully switches > on the midlevel currents that perpetuate the mild > warming > of an interglacial episode. The present warm > midlevel currents > self-limiting.They warm the poles enough to cause > melt > whose cold fresh water influx blocks and then shuts > off the > warming currents, and everything gets back to > "normal" if > the orbital timing is right. Interglacials are > episodes; they > never last. > > It's still an "ice age." It's been an "ice age" > for 14 my, or > 5-6 my, or 3.25 my or 2.2 my, depending on your > prejudices. > One thing is certain: it's an on-going condition. > Mountain glaciers, > continental glaciers, permanent sea ice, ice caps > miles thick: > they have merely shrunk --- they're still there. > There's still > permafrost and reindeers; they're just not located > in the > vicinity of the French Riviera right now. Don't sell > your > beachfront property yet. Just wait a while. > > We are a young species, whose entire evolution > has > been conducted during this same ice age; we regard > these > conditions as "normal." We are also accustomed to > this brief > pause in the usual severity, during which we crafted > the > entire mechanism of human "civilization," which has > quadrupled > our lifespan, and increased our population by a > factor of > one thousand, and given men the appearance of > magical > powers of flight, communication, and wizardly > devices. > (We are so evolved that there are even humans stupid > enough to weep at the thought that a few more > degrees of > warming would cause the permanent loss of even one > inch > of Our Beloved Ice. It's almost enough to cause one > to wish > that they were right. Intriguingly, these > disastrously sharp > coolings at 73,000 ya and 28,000 ya that precede > long and > bitter glaciations seem to have been themselves > immediately > preceded by a much shorter but very intense warming > episode.) > > Yes, we humans are Hot Stuff, obviously destined > to > "conquer" the solar system and this local short arm > of the > galaxy at the very least. If so, we had better get > up off our > bottoms and do it while we can. When (I didn't say > "if") The > Ice returns, all bets are off. The Ice is not an > enemy we can beat. > We are no more prepared to deal with it than our > paleolithic > ancestors were, and we will fare no better unless we > happen > to widely and comfortably inhabit the entire solar > system > and can simply use the Earth as an exotic winter > resort and > deep-ice history museum. > > That little fantasy is, of course, an optimistic > vision based on > the notion that humans are intelligent, foresightful > and purposed. > The Smart Money is on chewing reindeer hides to > soften them > for clothing, eating way too much red meat, hoping > your teeth > don't fall out before the first spring green edible > appears, trying > to maintain the art of the alphabet even though our > kids think > it's stupid and useless, and waiting for the Aliens > to show up. > > OK, OK, both are fantasies. Reality will depend > on dozens of > factors we can only guess at: the rate of changes, > the duration > of events, the depth of a future glaciation, how > cold? We could > possibly adapt to a gradual enough shift, assuming > we're willing > to give up the use of a portion of the planet, > double or triple or > more our population density, limp along from year to > year, > provided we're not pushed too hard. I suppose it all > depends > on how lucky we are. > > Like big impacts, continued glaciation is a > long-term certain > and short-term negligible risk (unless, of course, > runaway > Global Warming is our salvation in disguise). In the > immortal > words of Clint Eastwood's Dirty Harry, "Do you feel > lucky, > punk? Well, do ya?" > > > Sterling K. Webb > -------------------------------------------------------------------------------- > ----- Original Message ----- > From: "E.P. Grondine" <[EMAIL PROTECTED]> > To: <meteorite-list@meteoritecentral.com> > Sent: Thursday, March 29, 2007 9:55 AM > Subject: Re: [meteorite-list] Abstract: EL3 > Chondrite (not > Aubrite)NorthwestAfrica 2828 > > > Hello Sterling - > > The "present ice age" is not going to return. The > currents of the Pacific Ocean were altered by a > massive impact at the end of the last ice age, and > most likely that impact was what ended it. > > The important point here is how long NWA meteorites > have been accumulating, and as you point out it has > been a relatively short period. > > Ed > E.P. Grondine > Man and Impact in the Americas > $34.95 at amazon, or contact me off list > > ____________________________________________________________________________________ Food fight? Enjoy some healthy debate in the Yahoo! 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