The Earth has entered a new geological age: the Meghalayan, the third and last period since the beginning of the Holocene era started almost 12,000 years ago, announces the International Stratigraphy Commission (ISC), the organization responsible for establishing a geological time scale of the planet.
This age would have started more precisely 4,250 years ago, when a global drought struck our planet, estimates the International Union of Geological Sciences (IUGS). The Meghalayan is one of three newly named ages: the other two are Greenlandian (between 11,700 to 8,326 ago ) and Nordgrippian (between 8,326 to 4,250 ago).
Geologists have systematically divided and named the different periods of Earth’s history since its birth 4.54 billion years ago. These durations are known as eons, era, periods, epochs and ages. We are currently in the Phanerozoic eon, during the Cenozoic era, during the Quaternary period, in the Holocene epoch, and finally in the Meghalayan age.
To determine the start date of each age, scientists examine the unique chemical signatures found in the rock samples: each of them relates to a large climatic event. The Greenlandian, the earliest Holocene (Early Holocene) age, began 11,700 years ago, as the Earth left the last ice age. The NorthGrippian (Middle Holocene) began 8,300 years ago, when the Earth began to cool, probably because large amounts of fresh water from glaciers melted in the North Atlantic and disrupted ocean currents.
Meanwhile, the Meghalayan (Late Holocene) began 4,250 years ago, when a mega-drought devastated civilizations around the world, including Egypt, Greece, Syria, Palestine, Mesopotamia and the Middle East. This drought — which would have lasted 200 years – would have been caused by changes in ocean and atmospheric circulation.
Geologists chose the name “Meghalayen” as a nod to a rock sample they analyzed from Meghalaya, a state in northeastern India, whose name means “the home of the clouds” in Sanskrit. By analyzing a stalagmite that grows on the ground of the Mawmluh cave, geologists have noticed that each layer of stalagmites has different levels of oxygen isotopes (or oxygen versions) with different numbers of neutrons. This change would mark here the weakening of the conditions of the monsoon at the time.