At https://phys.org/news/2022-03-dating-boulders-ice-free-corridor-beringia.html … researchers have found evidence there was an ice free corridor between Beringia and the Great Plains, so it is said. The results are somewhat ambiguous as Beringia may have been drowned at the end of the Late Glacial Maximum – or a good deal of it. Are they saying Beringia still existed almost to the onset of the Younger Dryas? It is an article based on a dating technique. Interesting, nonetheless, and throws up some possibilities which are however not discussed. Basically, they are saying that the ice free corridor existed from 13,800 years ago. This is long after the end of the Late Glacial Maximum, after which sea levels rapidly rose, and within the warm period between the Oldest and the Younger dryas episodes. All somewhat mysterious. The idea of course is to pinpoint the arrival of humans into the Americas. What immediately sticks out is that 13,800 years ago is not that far away from the Clovis First dictum that was upended a few years ago, after a lot of resistance by the mainstream. Are they still clinging to the previous paradigm? Probably not. Some archaeologists have found evidence humans were in the Americas 15,000 years ago, and still others toy with the idea they were there 20,000 years ago.
Cosmogenic nuclide surface exposure involves measuring the effect of cosmic rays penetrating an object. In this case, a boulder. Of course, one cannot see inside a boulder unless you break it up so one assumes they were looking at the surface of the boulder. When cosmic rays strike they produce beryllium 10. This is the basic assumption of the dating claim. Sunlight, and cosmic rays, were blocked prior to 13,800, and the most obvious reason would be, they were covered in ice. The assumption is that an ice sheet covered the region yet there is a lot of evidence to say there was not an ice sheet in Beringia, Alaska, or parts of the Yukon during the Late Glacial Maximum. Therefore, ice during the post ice sheet phase is unlikely. Does that mean scientists should look at other reasons for a lack of beryllium 10? What was the sun doing at this time, and what might restrict an onslaught of cosmic rays?