A new phase in the Earth’s geological history was created by the scientists and is named as Meghalayan after a stalagmite discovered in a cave in Meghalaya. This stalagmite helped geologists define climatic events that took place 4,200 years ago and marks the beginning of the geological phase that continues till date.
This unique Meghalayan age initiated with a major drought that devastated agricultural civilisations from Egypt to China. It is unique because it is the first interval in the Earth’s geological history that coincides with a major cultural event. Moreover, this age is a part of a long period called the Holocene Epoch which contains everything that happened over the last 11,700 years.
Sediments have been found from all seven continents including those from Meghalaya which provided evidence of this climatic event. The droughts lasting over 200 years caused humans to migrate to Egypt, Greece, Syria, Palestine, Mesopotamia, Indus Valley and also in the Yangtze River valley. This global climatic change was most likely triggered due to oceanic shifts and atmospheric circulations.
These proposals were then forwarded to the IUGS for consideration where the executive committee unanimously voted to approve them. Also, two other ages namely the Middle Holocene Northgrippian age and the Early Holocene Greenlandian age with beginnings defined at climatic events that occurred around 8,300 years and 11,700 years ago respectively were approved by the International Commission of Stratigraphy.
Geologists divide the existence of Earth since 4.6 billion years into distinct periods. Each period is generally related to a significant event that occurs during that time such as climatic shifts, continental breakups and appearance of particular types of plant and animal species.
These geological periods are based on sedimentary layers accumulated over time and also contain different sediment types, fossils and chemical isotopes that record the events happened in time and the physical and biological events that caused them.
The three new ages of the Holocene Epoch are signified by the huge amount of sediments that are accumulated all over the world on sea floors and lake bottoms as glacial ice and calcite layers in stalactites and stalagmites.
These intervals of sedimentary layers are referred to as stages and the defined ages are based on them and together the sedimentary strata of the three new stages make the entire Holocene series.
For Greenlandian and Northgrippian stages, the lower boundary is defined at specified levels in Greenland ice cores. Similarly, for the Meghalaya stage, the lower level of the stage is defined at a specific level in a stalagmite found from the cave in Meghalaya. Now, the ice cores and stalagmites are identified as international geo-standards and are placed in a protective archive for further studies.

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