Geologists have discovered evidence that, at the end of the glacial era, about 56,000 years ago, the great canyon in the United States-one of the largest lands on the ground-turned for several hundred years into a very deep lake, following an earthquake caused by a meteorite.
According to Oxu.az, citing TASS, the information was communicated by the press service of the State University of New Mexico (US).
“We have prepared a large set of arguments in favor of the hypothesis of the ‘meteorite’, but we do not exclude other unusual events that could have blocked the course of Colorado River, including a local earthquake or a landslide. However, dating the traces of that lake – 55,600 years – it argues that the idea that it appeared in the same time,” Carl Karlstrom from the University of New Mexico, quoted by the institution’s press service.
Geologists have reached this conclusion by studying the fragments of some ancient logs, discovered by the teacher of the teacher-archaeologist-from the middle of the last century in one of the caves on the slopes of the great canyon.
Recently, their age was established with the new radiocarbon dating methods, and the researchers found that these trees have been in the cave for 56,000 years. This discovery attracted the attention of the geologists who studied the Barringer crater, appeared in the same period, a few tens of miles south-east.
This coincidence caused geologists to return to those caves, to collect new samples of rocks and organic debris, but also to make similar excavations in other rocky shelters on the territory of the great canyon. Subsequent measurements, made by two different methods in independent laboratories in Australia and New Zealand, have shown that all these samples were formed in the same period-now about 55,000-56,000 years.
According to Professor Karlstrom, some of the flooded wood samples were discovered in caves 940 m above the bottom of the big canyon, which contradicts the hypothesis that they were brought there by beavers, other animals or floods or temporary currents. For this reason, the researchers believe that the respective fish were flooded at the end of the glacial era and were either on the bank or under the waters of a prehistoric lake that covered much of the big canyon at that time.
According to the researchers, the lake appeared after the impact with the meteorite generated where the powerful seismics that caused the collapse of rocky formations in the Nankoweap region, where the geologists had previously found traces of a natural dam that would temporarily block the course of Colorado. When the water level reached the top of the dam, the rock remains were quickly eroded by the river currents, leading to the disappearance of the temporary lake that had occupied a large part of the big canyon, the scientists concluded.
