New Delhi:
Several geologists have sorted the last 4,200 years as being a distinct age in the story of our planet. Named after the ‘Meghalayan Age’, which was marked by a mega-drought that wiped off a number of civilisations across the world.
The International Chronostratigraphic Chart, the diagram visualising the timeline for Earth's history will be updated.
Geologists have divided up the 4.6-billion-year existence of Earth into slabs of time.
Each slab corresponds to significant happenings - such as the break-up of continents, shifts in climate, and the emergence of particular types of animals and plant life.
We currently survive in what is called the Holocene Epoch, which mirrors everything that has happened over the past 11,700 years - since a dramatic warming kicked us out of the last ice age. But the Holocene itself can be subdivided, according to the International Commission on Stratigraphy (ICS).
It is the official keeper of time and it proposed three stages be introduced to breakdown the epoch's upper, middle and lower phases.
These all record major climate events. The Meghalayan, the youngest stage, runs from 4,200 years ago to 1950. It began with a destructive drought, whose effects lasted two centuries, and severely disrupted civilisations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus Valley, and the Yangtze River Valley.
The Meghalayan Age is unique as it is the beginning that coincides with a global cultural event produced by a global climatic event, says Stanley Finney, professor of geological sciences at Long Beach State University and Secretary-General of the International Union of Geological Sciences (IUGS), which ratified the ICS proposal.
The middle phase of the Holocene will be termed as the Northgrippian, and runs from 8,300 years ago up to the start of the Meghalayan.
The oldest phase of the Holocene will be known as the Greenlandian.
For the Meghalayan, the spike is epitomised in specific chemical signatures, the finest example of which can be seen in the layers of rock formations on the floors of caves in the northeastern Indian state of Meghalaya.
Already the decision to differentiate ages within the Holocene has drawn fire from some scientists who believe the move is premature. They question whether some of the climate shifts used as anchors for the new ages were truly global in their impact.
They are also concerned that the divisions have been approved when there is still an active debate about assigning a new geologic slice of time to reflect specifically the influence of humans on the planet.
Tentatively referred to as the Anthropocene, its precise definition - its beginning point and the spike used to denote its initiation - is the subject of ongoing research.
