Categories
Culture, Society & Family Earth & Climate Fossils & Ruins Plants & Animals Researcher news SMU In The News

Zimbabwe Star: Comet not behind mass extinction at Ice Age end: Study

Meltzer, comet, Ice Age, SMU

The Zimbabwe Star news outlet has covered the research of SMU archaeologist David J. Meltzer with the article “Comet not behind mass extinction at Ice Age end: Study.”

A member of the National Academy of Sciences, Meltzer researches the origins, antiquity, and adaptations of the first Americans who colonized the North American continent at the end of the Ice Age. He focuses on how these hunter-gatherers met the challenges of moving across and adapting to the vast, ecologically diverse landscape of Late Glacial North America during a time of significant climate change.

The Zimbabwe Star, from the IANS news service, highlights Meltzer’s latest study to show that a comet, or any other kind of extraterrestrial impact, was not responsible for sudden climate change at the end of the Ice Age 12,800 years ago. Proponents of the comet-impact theory have pointed to sedimentary deposits that they say prove that an object from outer space hit the Earth, extinguishing the Clovis culture and causing the mass extinction of many animals.

Read the full story.

EXCERPT:

Zimbabwe Star (IANS)
Archaeologists have debunked the cosmic-impact theory that a comet sparked climate change at the end of the Ice Age, causing mass animal extinction.

According to the study, led by archaeologist David Meltzer from Southern Methodist University in Dallas, Texas, 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.

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 supposed impact markers are undated or significantly older or younger than 12,800 years ago. Either there were many more impacts than supposed, including one as recently as five centuries ago, or, far more likely, these are not extraterrestrial impact markers,” Meltzer noted.

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.

Meltzer and his colleagues 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.

Read the full story.

Follow SMUResearch.com on Twitter.

For more information, www.smuresearch.com.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

Categories
Culture, Society & Family Earth & Climate Fossils & Ruins Plants & Animals Researcher news SMU In The News

Daily Mail: A comet impact DIDN’T spark climate change and trigger a mass extinction 12,800 years ago, study claims

Daily Mail, Meltzer, SMU, comet, Clovis, mass extinction

The U.K.’s Daily Mail news outlet has covered the research of SMU archaeologist David J. Meltzer with the article “A comet impact DIDN’T spark climate change and trigger a mass extinction 12,800 years ago, study claims.”

A member of the National Academy of Sciences, Meltzer researches the origins, antiquity, and adaptations of the first Americans who colonized the North American continent at the end of the Ice Age. He focuses on how these hunter-gatherers met the challenges of moving across and adapting to the vast, ecologically diverse landscape of Late Glacial North America during a time of significant climate change.

The Daily Mail piece by Jonathan O’Callaghn highlights Meltzer’s latest study to show that a comet, or any other kind of extraterrestrial impact, was not responsible for sudden climate change at the end of the Ice Age 12,800 years ago. Proponents of the comet-impact theory have pointed to sedimentary deposits that they say prove that an object from outer space hit the Earth, extinguishing the Clovis culture and causing the mass extinction of many animals.

Read the full story.

EXCERPT:

By Jonathan O’Callaghan
Daily Mail

It has long been though that a comet struck Earth 12,800 years ago, bringing an end to the Ice Age.

This event was thought to have not only sparked climate change, but also killed America’s earliest people and caused a mass animal extinction.

But a new study suggests this comet theory is false, as most supposed impact indicators at 29 sites are too old or too young to be remnants of an ancient comet.

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 of the Southern Methodist University in 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.

His 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 after 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.

Read the full story.

Follow SMUResearch.com on Twitter.

For more information, www.smuresearch.com.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

Categories
Culture, Society & Family Earth & Climate Fossils & Ruins Plants & Animals Researcher news SMU In The News

Science: What Caused a 1300-Year Deep Freeze?

SMU, comet, Meltzer, Clovis points, Science

Science, the widely read news outlet of the American Association for the Advancement of Science, covered the research of SMU archaeologist David J. Meltzer with the article “What Caused a 1300-Year Deep Freeze?

A member of the National Academy of Sciences, Meltzer researches the origins, antiquity, and adaptations of the first Americans who colonized the North American continent at the end of the Ice Age. He focuses on how these hunter-gatherers met the challenges of moving across and adapting to the vast, ecologically diverse landscape of Late Glacial North America during a time of significant climate change.

The Science piece by Michael Balter highlights Meltzer’s latest study to show that a comet, or any other kind of extraterrestrial impact, was not responsible for sudden climate change at the end of the Ice Age 12,800 years ago. Proponents of the comet-impact theory have pointed to sedimentary deposits that they say prove that an object from outer space hit the Earth, extinguishing the Clovis culture and causing the mass extinction of many animals.

Read the full story.

EXCERPT:

By Michael Balter
Science

Things were looking up for Earth about 12,800 years ago. The last Ice Age was coming to an end, mammoths and other large mammals romped around North America, and humans were beginning to settle down and cultivate wild plants. Then, suddenly, the planet plunged into a deep freeze, returning to near-glacial temperatures for more than a millennium before getting warm again. The mammoths disappeared at about the same time, as did a major Native American culture that thrived on hunting them. A persistent band of researchers has blamed this apparent disaster on the impact of a comet or asteroid, but a new study concludes that the real explanation for the chill, at least, may lie strictly with Earth-bound events.

The study “pulls the rug out from under the contrived impact hypothesis quite nicely,” says Christian Koeberl, a geochemist at the University of Vienna. Most evidence for the extraterrestrial impact hypothesis, he says, was conjured up “out of thin air.”

The 1300-year big chill is known as the Younger Dryas, so-called because of the sudden worldwide appearance of the cold-weather flowering plant Dryas octopetala. A number of causes have been suggested, including changes in ocean currents due to melting glaciers and volcanic activity. In 2007, a diverse group of 26 researchers, led by nuclear chemist Richard Firestone of the Lawrence Berkeley National Laboratory in California, formally proposed what is known as the Younger Dryas impact hypothesis, in which one or more extraterrestrial bodies blew up over North America, leading to widespread wildfires and strewing sun-blocking dust and debris across the globe.

In a series of papers, Firestone and his colleagues claimed various kinds of evidence for the hypothesis, including deposits of the element iridium (rare on Earth but abundant in meteorites), microscopic diamonds (called nanodiamonds), and magnetic particles in deposits at sites supposedly dated to about 12,800 years ago. The notion was popularized in television documentaries and other coverage on the National Geographic Channel, History Channel, and the PBS program NOVA. These claims were sharply contested by some specialists in the relevant fields, however, who either did not detect such evidence or argued that the deposits had other causes than a cosmic impact. For example, some say that nanodiamonds are common in ordinary geological formations, and that magnetic particles could come from ordinary fires.

Now comes what some researchers consider the strongest attack yet on the Younger Dryas impact hypothesis. In a paper published online this week in the Proceedings of the National Academy of Sciences, a team led by David Meltzer, an archaeologist at Southern Methodist University, Dallas, in Texas, looks at the dating of 29 different sites in the Americas, Europe, and the Middle East in which impact advocates have reported evidence for a cosmic collision. They include sites in which sophisticated stone projectiles called Clovis points, used by some of the earliest Americans to hunt mammals beginning about 13,000 years ago, have been found, such as Chobot in Alberta, Canada, Murray Springs in Arizona, and Paw Paw Cove in Maryland; the site of Abu Hureyra in Syria, where evidence of plant-cultivating hunter-gatherers occurs; and sites in Greenland, Germany, Belgium, and the Netherlands where other evidence for an impact has been claimed. The team argues that when the quality and accuracy of the dating—which was based on radiocarbon and other techniques—is examined closely, only three of the 29 sites actually fall within the time frame of the Younger Dryas onset, about 12,800 years ago; the rest were probably either earlier or later by hundreds (and in one case, thousands) of years.

Read the full story.

Follow SMUResearch.com on Twitter.

For more information, www.smuresearch.com.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

Categories
Culture, Society & Family Earth & Climate Fossils & Ruins Plants & Animals Researcher news SMU In The News

Nature: Prehistoric impact idea smacked down — dates of reported cosmic collision can’t explain North American extinctions

Meltzer comet, Nature mag

Widely followed science magazine Nature covered the research of SMU archaeologist David J. Meltzer with the article “Prehistoric impact idea smacked down.

A member of the National Academy of Sciences, Meltzer researches the origins, antiquity, and adaptations of the first Americans who colonized the North American continent at the end of the Ice Age. He focuses on how these hunter-gatherers met the challenges of moving across and adapting to the vast, ecologically diverse landscape of Late Glacial North America during a time of significant climate change.

The Nature piece by Alexandra Witze focuses on Meltzer’s latest study to show that a comet, or any other kind of extraterrestrial impact, was not responsible for sudden climate change at the end of the Ice Age 12,800 years ago.

Proponents of the comet-impact theory have pointed to sedimentary deposits that they say prove that an object from outer space hit the Earth, killing the Clovis culture and causing the mass extinction of many animals.

Read the full story.

EXCERPT:

By Alexandra Witze
Nature

One of the most controversial ideas about prehistoric North America — that an impact by an extraterrestrial object 12,800 years ago triggered a cold snap that killed off mammoths and decimated early human populations — is under fresh attack. Independent archaeologists have reanalysed the dates of geological material that reportedly represents the impact, and found that they do not match.

Supporters of the impact theory have put forth 29 sites, from North America to Europe and beyond, that contain a thin layer of sediments said to date to the start of the cosmic impact event. The latest study checked to see whether those sites were all really 12,800 years old.

Only 3 of the 29 are, the researchers report today in the Proceedings of the National Academy of Sciences1. The other sites either have not been dated using the usual radiometric methods, or are much older or younger than the reported impact. “The chronology doesn’t hold up,” says team leader David Meltzer, an archaeologist at Southern Methodist University in Dallas, Texas.

There is no doubt that something important happened in this region around 12,800 years ago. Temperatures in the Northern Hemisphere plummeted in a cold spell known as the Younger Dryas, and sophisticated hunters known as the Clovis people vanished from what is now the western United States. Many of North America’s famous large mammals, such as mammoths, went extinct

Carbon footprint
Impact proponents say that many lines of evidence point to a cosmic object crashing into Earth at the time2. These include reported tiny diamonds formed in the high pressure of an impact, and soot and charcoal from fires possibly triggered by the smash. Opponents counter that there are other explanations for these materials, and that a comet blast should have left a huge fingerprint in the geological record — but nothing of the sort has been found.

Meltzer’s team includes experts on North American Palaeoindians. “We know some of these sites, we’ve worked at some of these sites,” he says. “When we started to read the details [of the impact theory], it just didn’t add up.”

Read the full story, with audio.

Follow SMUResearch.com on Twitter.

For more information, www.smuresearch.com.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]

Categories
Culture, Society & Family Earth & Climate Fossils & Ruins Plants & Animals

Comet theory false; doesn’t explain cold snap at the end of the Ice Age, Clovis changes or mass animal extinction

Most supposed impact indicators at 29 sites are too old or too young to be remnants of an ancient comet that proponents claim sparked climate change at the end of the Ice Age, killed America’s earliest people and caused a mass animal extinction

Comet, Meltzer, SMU, Clovis, boundary layer

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, 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.

Meltzer is the Henderson-Morrison Professor of Prehistory in the SMU Department of Anthropology in Dedman College and a member of the National Academy of Sciences. — Margaret Allen

Follow SMUResearch.com on Twitter.

For more information, www.smuresearch.com.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.