NEW DELHI: It's official, we live in the Meghalayan Age. Scientists have created a new phase in Earth's geological history and named it Meghalayan, after a stalagmite from a cave in the Indian state of Meghalaya that helped define climatic events 4,200 years ago, marking the beginning of the phase that continues till today.The Meghalayan Age began with a mega global drought that devastated ancient agricultural civilisations from Egypt to China. It is part of a longer period known as the Holocene Epoch, which reflects everything that has happened over the past 11,700 years.The Meghalayan is unique because it is the first interval in Earth's geological history that coincided with a major cultural event, as agricultural societies struggled to recover from the shift in climate, said Stanley Finney, secretary general of the International Union of Geological Sciences (IUGS). Evidence of the climatic event has been found in sediments on all seven continents, including those from Meghalaya.The droughts over a 200-year period resulted in human migrations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus valley and the Yangtze river valley.The change in global climate was likely triggered by shifts in ocean and atmospheric circulation.The commission then forwarded these proposals to its parent body, the IUGS, for consideration, and the executive committee of IUGS voted unanimously to ratify them.Two other ages — the Middle Holocene Northgrippian Age and the Early Holocene Greenlandian Age — with beginnings defined at climatic events that happened about 8,300 years and 11,700 years ago, respectively, were also approved by the International Commission on Stratigraphy, which is responsible for standardising the geologic time scale.Geologists divide the 4.6-billion-year existence of Earth into distinct periods. Each period corresponds to significant events such as the break-up of continents, shifts in climate, and the emergence of particular types of animals and plant life.These units of the geologic time scale are based on sedimentary strata that have accumulated over time and contain within them sediment types, fossils and chemical isotopes that record the passage of time as well as the physical and biological events that produced them.The three new ages of the Holocene Epoch are represented by a wealth of sediment that accumulated worldwide on the sea floor, on lake bottoms, as glacial ice, and as calcite layers in stalactites and stalagmites.Those intervals of sedimentary strata on which the ages are based are referred to as stages, and together the strata of three new stages comprise the Holocene series.The lower boundary of the Greenlandian and Northgripppian stages are defined at specific levels in Greenland ice cores. The lower boundary of the Meghalayan stage is defined at a specific level in a stalagmite from a cave in the northeastern Indian state.The ice cores and the stalagmite are now identified as international geostandards, and have been placed in protected archives accessible for further study.