Two other, previous Ages were declared by the ICS: the Early Holocene Greenlandian Age that began about 11,700 years ago, and the Middle Holocene Northgrippian Age that began 8,300 years ago, before being supplanted by the Meghalayan. Our Meghalayan Age began with a mega-drought, the effects of which lasted for two centuries.
All three ages comprise the "Holocene Epoch", which began at the end of the last Ice Age and have been characterized by a wealth of sediment found on the sea floor and of the mineral calcite found in caves. Together, these three stages stretch across the Holocene Epoch, which is the "epoch" or "series" we've been living in for the past 11,700 years.
The commission has released International Chronostratigraphic Chart to show all the divisions in the Earth's 4.6 billion-year history. The new grouping is named after a particular rock formation found in a cavern in the upper east of India. But the Holocene itself can be subdivided, according to the International Commission on Stratigraphy (ICS). This latest geological epoch of Earth started with a global warming event that pushed the planet out of the last Ice Age. The onset for this age was an abrupt cooling, attributed to vast volumes of freshwater from melting glaciers in Canada running into the North Atlantic and disrupting ocean currents. Analysis of stalagmite growing on the ground of Mawmluh Cave revealed that each of the stalagmite layers had different levels of oxygen isotopes.
The lower boundary of the Greenlandian and Northgripppian stages are defined at specific levels in Greenland ice cores.
It should be said, however, there is disquiet in the scientific community at the way the change has been introduced.
"The isotopic shift reflects a 20 to 30 percent decrease in monsoon rainfall", geologist Mike Walker of the University of Wales explained to BBC News. The Meghalayan, the youngest stage, runs from 4,200 years ago to 1950. The proposals were developed by a dedicated, global team of Holocene scientists led by Mike Walker of the University of Wales. Agricultural-based societies that developed in several regions after the end of the last Ice Age were impacted severely by a 200-year drought, a climatic event that resulted in the collapse of civilisations and human migrations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus Valley, and the Yangtze River Valley. Mark Maslin, a geography professor at University College London, tells BBC News, "After the original paper and going through various committees, they've suddenly announced [the Meghalayan] and stuck it on the diagram. Beautiful, I know!" someone commented, but we recommend that you follow the entire thread on Twitter. This epoch, which has yet to be submitted to or approved by the ICS, would recognize the geological impact humans have had on the planet.
The new updates help understanding more about Earth's full geological history.