Posted on 05/17/2014 12:06:11 PM PDT by Renfield
Controversy over what sparked the Younger Dryas, a brief return to near glacial conditions at the end of the Ice Age, includes a theory that it was caused by a comet hitting the Earth.
As proof, proponents point to sediments containing deposits they believe could result only from a cosmic impact.
Now a new study disproves that theory, said archaeologist David Meltzer, Southern Methodist University, Dallas. Meltzer is lead author on the study and an expert in the Clovis culture, the peoples who lived in North America at the end of the Ice Age.
Meltzer's research team found that nearly all sediment layers purported to be from the Ice Age at 29 sites in North America and on three other continents are actually either much younger or much older.
Scientists agree that the brief episode at the end of the Ice Age — officially known as the Younger Dryas for a flower that flourished at that time — sparked widespread cooling of the Earth 12,800 years ago and that this cool period lasted for 1,000 years. But theories about the cause of this abrupt climate change are numerous. They range from changes in ocean circulation patterns caused by glacial meltwater entering the ocean to the cosmic-impact theory.
The cosmic-impact theory is said to be supported by the presence of geological indicators that are extraterrestrial in origin. However a review of the dating of the sediments at the 29 sites reported to have such indicators proves the cosmic-impact theory false, said Meltzer.
Meltzer and his co-authors found that only three of 29 sites commonly referenced to support the cosmic-impact theory actually date to the window of time for the Ice Age.
The findings, "Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago," were reported May 12, 2014, in the Proceedings of the National Academy of Sciences.
Co-authors were Vance T. Holliday and D. Shane Miller, both from the University of Arizona; and Michael D. Cannon, SWCA Environmental Consultants Inc., Salt Lake City, Utah.
"The supposed impact markers are undated or significantly older or younger than 12,800 years ago," report the authors. "Either there were many more impacts than supposed, including one as recently as 5 centuries ago, or, far more likely, these are not extraterrestrial impact markers."
Dating of purported Younger Dryas sites proves unreliable
The Younger Dryas Impact Hypothesis rests heavily on the claim that there is a Younger Dryas boundary layer at 29 sites in the Americas and elsewhere that contains deposits of supposed extraterrestrial origin that date to a 300-year span centered on 12,800 years ago.
The deposits include magnetic grains with iridium, magnetic microspherules, charcoal, soot, carbon spherules, glass-like carbon containing nanodiamonds, and fullerenes with extraterrestrial helium, all said to result from a comet or other cosmic event hitting the Earth.
Meltzer and his colleagues tested that hypothesis by investigating the existing stratigraphic and chronological data sets reported in the published scientific literature and accepted as proof by cosmic-impact proponents, to determine if these markers dated to the onset of the Younger Dryas.
They sorted the 29 sites by the availability of radiometric or numeric ages and then the type of age control, if available, and whether the age control is secure.
The researchers found that three sites lack absolute age control: at Chobot, Alberta, the three Clovis points found lack stratigraphic context, and the majority of other diagnostic artifacts are younger than Clovis by thousands of years; at Morley, Alberta, ridges are assumed without evidence to be chronologically correlated with Ice Age hills 2,600 kilometers away; and at Paw Paw Cove, Maryland, horizontal integrity of the Clovis artifacts found is compromised, according to that site's principal archaeologist.
The remaining 26 sites have radiometric or other potential numeric ages, but only three date to the Younger Dryas boundary layer.
At eight of those sites, the ages are unrelated to the supposed Younger Dryas boundary layer, as for example at Gainey, Michigan, where extensive stratigraphic mixing of artifacts found at the site makes it impossible to know their position to the supposed Younger Dryas boundary layer. Where direct dating did occur, it's sometime after the 16th century A.D.
At Wally's Beach, Alberta, a radiocarbon age of 10,980 purportedly dates extraterrestrial impact markers from sediment in the skull of an extinct horse. In actuality, the date is from an extinct musk ox, and the fossil yielding the supposed impact markers was not dated, nor is there evidence to suggest that the fossils from Wally's Beach are all of the same age or date to the Younger Dryas onset.
At nearly a dozen other sites, the authors report, the chronological results are neither reliable nor valid as a result of significant statistical flaws in the analysis, the omission of ages from the models, and the disregard of statistical uncertainty that accompanies all radiometric dates.
For example, at Lake Cuitzeo, Mexico, Meltzer and his team used the data of previous researchers and applied a fifth-order polynomial regression, but it returned a different equation that put the cosmic-impact markers at a depth well above that which would mark the Younger Dryas onset.
The authors go on to point out that inferences about the ages of supposed Younger Dryas boundary layers are unsupported by replication in more cases than not.
In North America, the Ice Age was marked by the mass extinction of several dozen genera of large mammals, including mammoths, mastodons, American horses, Western camels, two types of deer, ancient bison, giant beaver, giant bears, sabre-toothed cats, giant bears, American cheetahs, and many other animals, as well as plants.
I haven't looked at your posting history so I don't know if you're a hit and run type or not. It is a curiosity to me that some people, when offered compelling data opposing their views, fall off a cliff, or something. You are still around, aren't you???
No matter. SunkenCiv probably spent a good deal of time compiling a somewhat dated(now) but exhaustive FR list on the subject that you might find interesting; or not, HERE.
Let me know if you would like to see additional stuff or if you would just as soon discontinue the conversation.
I took a brief look, but I’ve never been much of a believer in Atlantis and Mu and such. I have a scientific POV, and little interest in what I, to be frank, classify as woo-woo stuff.
I also didn’t want to argue the point with a true believer, since I don’t feel any kind of a need to disprove their existence either. So I got bored and left.
No offense intended, just didn’t see how either of us would profit by continued conversation on the subject.
I realize that wasn’t particularly polite. I should have expressed my lack of interest in continued conversation on the subject. The Web, due to its anonymous nature, has a tendency to encourage less than courteous behavior.
My apologies.
I’ve been away a lot, real life stuff.
No offense taken of course. My expressed sensitivity was more tongue in cheek than anything else, but you probably know that.
...just didn’t see how either of us would profit by continued conversation on the subject.
Interesting. You can not or will not be swayed by arguments presenting evidence contrary to your, er, faith??? And you have to admit your opinions on the subject are what you choose to believe as much as anything else. Scientific POV? I dunno. Regardless, I like a good debate and I CAN be swayed with compelling evidence.
Up until about fifteen years ago or so I was what I would classify an agnostic. I probably leaned towards catastrophism but didn't know what to believe and honestly didn't care much one way or the other. Furthermore I couldn't see that it really made much difference. Until I discovered malfeasance by many in the scientific community™.
I can't even begin to guess how many hundreds of hours I have spent digging, searching, studying and scratching my head in an effort to find out what was and is going on. Much of that done here on FR with the able assistance of other Freepers or spun off from FR. I even discovered that Darwin himself didn't know what to make of the obvious devastation that apparently occurred during historical times(pick an arbitrary date of, say, less than 20K years ago). It was everywhere he looked, particularly in the Americas. It seems his work was co-opted by his benefactor and mentor Charles Lyell who turned it into the uniformitarian/gradual evolutionary nonsense we see til this day. To what purpose I haven't a clue, but there it is.
Have a good day.
Been off more than on the last few months myself but more a matter of frustration with FR than any real life stuff.
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