The Earth is now in a new geological age. The International Union of Geological Sciences said that this age, dubbed the Meghalayan, started 4,250 years ago when drought struck the planet.
We are currently in the Holocene Epoch, which reflects all that have happened over the last 11,700 years, since after the last ice age. The epoch itself, however, is subdivided into different periods called stages or ages, and we are now it its youngest stage.
In a statement released on July 13, the IUGS said this age, the Meghalayan, is one of the three newly named stages for the Holocene Epoch.
The other two are the Greenlandian, which occurred 11,700 years to 8,326 years ago, after the last ice age, and the Northgrippian, which occurred 8,326 years to 4,250 years ago, when Earth abruptly started cooling possibly as a result of the vast amounts of fresh water from melting glaciers.
"The Holocene is now defined by three stages: the Lower Holocene Greenlandian Stage, the Middle Holocene Northgrippian Stage, and the Upper Holocene Meghalayan Stage," the IUGS International Commission on Stratigraphy (ICS) said in a statement. "The lower boundary of each is placed at an carbon isotope excursion that defines the respective climatic event."
The Meghalayan Age
Meghalayan started with a global drought that had devastating impacts on ancient civilizations including those in China, Greece, Mesopotamia, Syria, Palestine, the Indus Valley, and the Yangtze River Valley. The mega-drought, which spanned for 200 years, was likely the result of shifts in ocean and atmospheric circulation.
The name "Meghalayan" is a nod to a rock sample that geologists analyzed from Meghalaya in India. Analysis of stalagmite growing on the ground of Mawmluh Cave revealed that each of the stalagmite layers had different levels of oxygen isotopes.
"The isotopic shift reflects a 20-30 [percent] decrease in monsoon rainfall," said Mike Walker, from the University of Wales, UK. "The two most prominent shifts occur at about 4,300 and about 4,100 years before present, so the mid-point between the two would be 4,200 years before present, and this is the age that we attribute to the [Meghalayan golden spike]."
What Makes The Meghalayan Age Unique?
IUGS Secretary General Stanley Finney said that the Meghalayan is unique from other intervals of the Geologic Time Scale because its beginning marks a major cultural event associated with global climatic events. It fall at a time period when societies sought to recover from the changes in climate.