Studies show that it was not until 138 years ago that the ice wall blocked the land of America-

A long-debated question about American settlement is whether the first humans arrived there through Siberia-Alaska land called Bering Root or by boat along the Pacific coast. Now, a new study published in the Proceedings of the National Academy of Sciences (PNAS) studies whether there was an ice-free corridor along the Bering Gorge route from Asia to the Great Plains of North America during the first human migration. They found that until about 13,8 years ago, a huge ice wall 3, feet high (914 meters high) blocked the land passage. This means that before the huge ice wall melted 13 thousand years ago, this sea route was the only way for the earliest immigrants.

According to ATI, an international research team led by Jorie Clark, a geologist and archaeologist at Oregon State University, tried to solve the dispute about when and how the first human settlers arrived in North America by determining the exact age of the ice-free corridor.

The focus of this latest research is when the huge ice wall in North America existed and when it didn't exist, and how it related to the migration of human beings using any land route before the ice wall receded about 13, years ago. This map shows the extent of Cordilleran and Laurentide ice fields after they first opened the ice-free corridor 13, years ago, and the location of rock samples used to prove their theory. Journal of the National Academy of Sciences (PNAS)

How the ice wall theory changed Clovis theory

The question about land or sea migration actually depends on when the first humans arrived in America. For a long time, people thought that Clovis was a group of hunter-gatherers of prehistoric ancient Americans, who came to North America from Siberia along the inland ice-free corridor (IFC) formed after the last ice age about 13,5 years ago. Clovis people got their names from their unique stone tools, which were first discovered near Clovis people in New Mexico in the 192s.

Recently, however, scientists have found evidence of human existence in America long before Clovis. According to Life Science, in 221, 6 ancient human footprints were discovered in New Mexico, dating back to 23, years ago. In 22, stone tools about 26,5 years ago were unearthed in central Mexico. At this time, the Bering land bridge was covered by a huge ice wall, which blocked the way for people who wanted to immigrate to North America.

the theory of ice wall and ice-free corridor tends to travel by sea

The land route hypothesis is based on the dating of the ice-free corridor (IFC) in the Rocky Mountains. To find out when immigrants began to use this land route, Clark and his team collected 64 geological samples from six locations, which spanned 745 miles. It is said that this corridor once existed in what is now British Columbia and Alberta. By observing the radioactive elements in these rocks, they determined the time when these rocks were exposed to the sun.

"We used a method called cosmogenic nuclide exposure time labeling, which is a" rock clock "that can tell us how long the rocks on the earth's surface were exposed to the sun after the glacier retreated."

Clark told Life Science that they found that about 13,8 years ago, the area might be covered by huge ice sheets. "In the area covered with ice-free corridors, it might be 1,5 to 3, feet (455 to 91 meters) high .... We now have strong evidence that the ice-free corridor is not open and available to the first people in America. "

Early research shows that the ice-free corridor was formed about 15, years ago. The discovery of Clark's team promoted the view that the corridor was "completely open" to some extent.

the researchers added other ideas. They clarified that they did not mean that the ice-free corridor was not used for human migration at all, but that the first batch of human immigrants to America did not use it. Clark said that once the corridor is opened, later people may choose a more direct land route.

"We have closed the door of the ice-free corridor. This study clearly shows that when people first entered America about 2, years ago, the corridor was not opened as a migration route, "said Dr. Dylan.

But Clark warned that there is still a lot to know about whether the first immigrants really used coastal routes and, if so, what kind of ships they took. In order to further reveal the earliest wave of human migration to America, it is necessary to explore archaeological sites from migration routes.