The calving of icebergs of Greenland glaciers can transport rocks on the distant banks
Professor Ross Mitchell
The rocks transported from Greenland to Iceland by icebergs add to proof that the climate in Europe has become much colder for a century or two from 540 AD – a “Ice mini” which could have played a role in the fall of the Roman Empire.
This cold period in the northern hemisphere, which was previously indicated by studies on trees of trees and sediment nuclei, has been linked to a number of historical events around the worldFrom the collapse of the Northern Wei dynasty in China to the decline in the state of the city of Teotihuacan in Central America. Justinian's plagueWho affected the Eastern Roman Empire after the fall of the Western Roman Empire in 476, may also have been partly caused by a colder climate.
Christopher Spencer At Queen's University in Kingston, Canada, and his colleagues decided to explore a beach on the west coast of Iceland because the satellite photos showed that it was light rather than the basalt black of almost all the other beaches in Iceland.
This lighter color turned out to be due to the presence of many shells, but walking in the region, Spencer has spotted pavement granite stones. For him, it was instantly clear that these rocks were not Iceland. “It's a bit annoying how easy it was to discover,” he says.
Indeed, an analysis of the rocks confirmed that they came many different places in Greenland, which is located about 300 kilometers from Iceland at the nearest points. This means that the rocks that Spencer found must have been transported by icebergs that have gripped the Greenland glaciers and were washed on the beach.
The layer of the beach in which the Greenland rocks are present has already been dated 500 AD, explains Spencer. While the Icebergs of Greenland still reach this area, the Greenland rocks were not found in any other layer of the beach.
A collection of old rocks analyzed in the study, which were found in Greenland
Dr Christopher Spencer
Thus, the discovery shows that a large number of icebergs in Greenland get up on this beach during the period when this layer was formed. This suggests that due to colder conditions, the Greenland glaciers grew up and has dressed many more icebergs during this period, explains Spencer.
This is carefully linked with evidence of a colder period sometimes called the little antique late glacial period. The cause of this event is not clear – some think He was triggered by volcanoesothers by fragments of a comet striking the earth. Spencer thinks that it was simply orbital changes affecting the amount of heat from the sun reaches the earth.
While the extent to which the climate has contributed to events such as the fall of Rome remains debated, there is more and more proofs Climate change has shaped the fate of many civilizations.
