You are now living in a new era of geological history, but it didn’t just start. Scientists have (mostly) agreed on a new way to divide up Earth’s recent history that includes additions to the accepted geological charts. According to the latest version of the International Chronostratigraphic Chart from the International Union of Geological Sciences (IUGS), we are living in the Meghalayan Age.
There are several different ways of breaking up the 4.6 billion year geological history of Earth. We currently live in the Holocene Epoch, which is not a new concept. This period started 11,700 years ago at the end of the last ice age. What is new is the segmentation of the Holocene Epoch into three distinct periods. The earliest block is now known as the Greenlandian Age (11,700 to 8,300 years ago), and following that was the Northgrippian (8,300 to 4,200 years ago). The current Meghalayan Age began 4,200 years ago and runs to this very day.
Each division in the International Chronostratigraphic Chart corresponds to some distinctive change in the strata of Earth. For example, the end of the Cretaceous is marked by iridium sediments most likely deposited by an asteroid impact. The Meghalayan Age is indicated by a much more subtle change, which has naturally led to some disagreement in the scientific community.
The latest version of the International Chronostratigraphic Chart/Geologic Time Scale is now available! New #Holocene subdivisions: #Greenlandian (11,700 yr b2k)#Northgrippian (8326 yr b2k)#Meghalayan (4200 yr before 1950) https://t.co/IhvZHfHnWh#ChronostratigraphicChart208 pic.twitter.com/8Pf9Dnct7h
— IUGS (@theIUGS) July 13, 2018
The concept of the Meghalayan Age was only proposed six years ago by the International Commission on Stratigraphy (ICS). The IUGS recently ratified that proposal. Scientists point to shifts in oxygen isotopes caused by a massive global drought around 4,200 years ago. Researchers believe this drought may have lasted up to a century and caused the collapse of many early civilizations, including the Old Kingdom of Egypt, the Akkadian Empire in Mesopotamia, and the Liangzhu culture of China. The few contemporary sources from this era report drastically reduced rainfall.
Those who oppose the change contend that the shifts used as markers of the Meghalayan Age may not have been truly global in nature. From that perspective, it doesn’t belong on the International Chronostratigraphic Chart. They also complain that the IUGS moved unusually fast to make this change and didn’t take the time to consider opposing viewpoints.
There may be even more changes coming, too. Some researchers think the chart should recognize an even newer slice of time known as the Anthropocene Epoch. That would recognize the global changes precipitated by human activity. That modification is still far from official, though.
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