Geologists have marked a new phase in the history of earth after
discovering evidences in Meghalaya, India
The current age which we are living in has been recently officially designated at the ‘Meghalayan Age’ by the International Geologic Time scale. This scale divides the history of our planet into different eons, eras, periods, epochs and ages. The timing of events on the basis of which these time periods are divided is collated by geologists and archaeologists worldwide and is based upon substantial events like continents breaking up, dramatic change in climatic conditions, extinction or emergence of certain animals and plants. The units of this scale are based upon proof and evidence of sedimentary layers which have collected over time and these layers contain different sediments, fossils and chemical isotopes. Such strata bear recordings through a passage of time which also convey associated physical and biological events. This is called geologic age dating where each of such material are assigned an age and then the likely events around it are predicted. This is how we know today that earth is 4.6 billion years old. The International Commission on Stratigraphy (IUGS) is chiefly responsible for regulating the Geologic Time Scale.
The current era that we live in, - the Holocene epoch - has been updated and subdivided into three new geological ages which are Early Holocene called Greenlandian, Middle Halocene called Northgrippian and Late Halocene called the Meghlayan age. Greenlandian age is marked when the ice age came to an end and warming started on earth around 12000 years ago. Northgrippian age started around 8000 years ago. Both these ages are marked by ice cores found in Greenland. A new distinct Meghalayan age which has now been identified started 4,200 years ago and is till today. The agency International Union of Geological Sciences is responsible for these international standards in geology. Researches have taken up to eight years to mark the dates for the Meghalayan age.
All ages have been assigned unique names based upon their origin or start. The Greenlandian and Northgrippian ages are named for the NorthGRIP site in Greenland. This site depicts the swift warming of the planet signifying the culmination of ice age followed by a swift universal cooling at the start of Northgrippian age which was caused by entry of melted ice water into the North Atlantic. Further, around 4,200 years ago, a significantly drier phase or aridification has been identified by researchers which they have designated as the start of Meghlayan Age. The Meghalayan age is termed after a stalagmite (a type of rock formation) in Mawmlul cave located in the north eastern state Meghalaya in India to mark the exact origin of this age. The word “Meghalaya’ means “the abode of clouds” in Sanskrit. The timestamp of this age is understood by explaining that this stalagmite was deposited on the floor of the cave from minerals deposits over several thousands of years because of the rain water seeping inside the cave through ceiling drippings. This occurred most probably because of ocean shifts and atmospheric circulation. The mineral layers depict the change in precipitation over time as their chemical signatures show that a single stalagmite’s change in oxygen atom isotopes led to the area experiencing 20-30 percent decrease in monsoon rainfall. This is being considered as significant evidence for this discovery. In fact, such evidence has been discovered on all seven continents on Earth. This ‘mega draught’ launched the new geological age. Such extreme climatic conditions also would have left to collapse of civilizations and uprooting of human settlements especially those engaged in agriculture near the Mediterranean Sea, the Middle East and Asia as indicated in studies. The effects of this ‘mega draught’ appear to have lasted for over 200 years. Many experts believe this event to be vastly connected with social and economic reasons.
The smallest global climatic event in the history of our planet has been discovered for the first time and it furthers our understanding of Earth’s complete geological history. This is a remarkable discovery and an addition into the history of Holocene and also archaeology. Geologists are planning to add a new epoch after the Holocene which is being called the Anthropocene which would mark the impact of humans on the geology of the planet after industrialization.
International Commission on Stratigraphy, www.stratigraphy.org, accessed Aug 5, 2018