New evidence supports the coastal path for the American people

New evidence supports the coastal path for the American people

Transport of rocks through glaciers.

Transport of rocks through glaciers.
PhotoIan Watkinson / EGU

New evidence suggests that the opening of the ice-free corridor connecting Beringia in the interior of North America occurred thousands of years after the first human migration to the continent. Scientists say the discovery reinforces the notion that ancient humans traveled to the United States by sea, but other researchers are skeptical.

New ones Research The processes of the National Academy of Sciences date back to about 13,800 years ago with the appearance of the ice-free corridor connecting Beringia to the Great Plains. Previous estimates suggest that the bass appeared about a thousand years ago, at the end of the last ice age. According to Previous archeological works, The first human migration to the North American continent occurred about 15,000-16,000 years ago, and 20,000 years ago. The authors of the new study reinforce their findings on the hypothesis of coastal migration, in which the first humans to reach the United States traveled along the Pacific coast.

“The snow-free corridor has always played an important role in the demographics of the United States, but our results provide strong evidence that the ice-free corridor is not open and inaccessible for this purpose,” Jury Clark said. Paper and Science Land, Ocean and Atmosphere College researcher at Oregon State University explained in an email. “This has already been decided, but the evidence for the age of the snow-free trail is very uncertain and cannot be used conclusively to solve this question in any way.”

Clark and colleagues used a dating method called “cosmic nuclide surface exposure dating”, which “works by dating when an iceberg was first moved from the site, indicating how long ago that ice was deposited. First by ice.” It also revealed to the atmosphere: “In simple terms, they calculated cosmic ray attacks to find out how long a rock has been on the Earth’s surface.

In an email, Ben Potter, an archaeologist at the Center for Arctic Studies at Liacheng University in China, who is not involved in new research, said he “did not believe” the paper. Dating with cosmic exposure gives a minimum age, not a maximum age, and researchers have so far given no reason for other attempts to open the ice. Research This shows that a snow-covered, lake-free valley appeared at least 15,000 years ago.

Since this has implications for Clovis’ first hypothesis, it is important to determine the timing of the land route connecting Eurasia and North America. The theory is that people living in Alaska and Yukon traveled to the large plains in the southern interior, where they settled the Clovis culture, which was named for their unique stone tools. Recent archaeological and genetic evidence has cast doubt on this theory, pointing out that the massive Cordilleran and Laurentite glaciers retreated, instead pointing to Clovis’ earlier immigration to the United States. Scientists wrote in a new study that “solving this debate on immigration is essential to answering questions about when and how Americans first arrived.”

Clark said previous studies using other dating techniques were limited. For example, “The radiocarbon date of a portion of organic fossils dates back to the time when fossils were alive, which could have been any time after the ice-free path opened – we do not know how long before the date. The Foundation opened the International Fund.” It is defined in terms of geographical purpose and number of samples analyzed, compared to previous research using cosmic exposure from the history of the ice-free corridor.

For the new analysis, Clark and his team explored 745 miles (1,200 km) of ice-displaced rocks in the Cordilleran-Laurentite ice sheet, which allowed them to be sampled from 64 manifestations of the universe. He explained that the team “was able to assess a number of uncertainties in the data and obtain a strong average date for each location”. The use of cosmic rays to date rocks may seem strange, but Clark likened it to brown.

“When a rock is first placed by retreating ice, it will be exposed to the atmosphere for the first time, including cosmic rays coming from space, traveling through the atmosphere and hitting the Earth’s surface,” Clark explains. “It feels like sitting outside for the first time after being indoors all winter and starting to emerge in the sun. As soon as the rock is first exposed, cosmic rays penetrate the rock and produce new elements – cosmic nuclides – inside the rock, so the concentration of these elements increases over time.

Scientists can measure the concentration of these elements in the laboratory, and because they know how many new elements are produced each year, “the retreat of ice can calculate the time it took for the rock to first appear,” Clark said. “Some people will question our dating system, but we hope that age adjustment will not change our basis,” Clark said. “We are very confident in our results.”

Potter did not share this belief, using only one standard deviation to explain the team when two were needed. When using a more conservative value, the new evidence suggests a minimum age for ice exposure for some period between 13,000 and 15,600 years, he said. This uncertainty is consistent with optically induced and infrared induced fluorescence dating efforts, suggesting a snow-free corridor formed at least 15,000 years ago, Potter said.

One of the key findings of the new study is that the viable route for the first wave of people to enter North America via land did not exist until at least 13,800 years ago, and should have been done by previously displaced people. Pacific coast. It may not be like that. Not surprisingly, other evidence, such as 15,000-year-old archeology, was given Guide On the Coopers Ferry in Idaho.

Potter thinks we should not rule the inner way yet. 11,500 and 14,000 years ago, he said, “there is no widespread consensus as to whether the old age of coal scattered on the Cooper Boat was related to occupation.” Thus, 15,000 years later, Potter wrote, “the ice-free path to the early clearings south of the glaciers cannot be ruled out.” As he points out, there are no sites undoubtedly dated along the North Pacific coast 12,600 years ago, and 9,000 years ago from the Kuril Islands to the Aleutian Islands and south-central Alaska, which is a fair thing. .

Clark seems to agree with this last comment. “While we’re answering the question about America’s first settlers, did they really get to the coast? If so, we still need to learn a lot more about how they traveled – we need to find archaeological sites from this region,” he said. She said in the email.

The question of when an inner passage appeared and how early humans were able to find their way to the continent remains unresolved. Like archeology, we need additional evidence if we are to truly understand this significant period in human history.

See also  From Africa to the Americas: Many Red Devils have already arrived before Alderwild

Leave a Reply

Your email address will not be published.