No one knew about the glistening proof from a stalagmite found from a cave of Meghalaya would define an entirely new era of Earth’s 4.54 billion year history, setting a new age that dawned 4,200 years ago.
The carbonate formed by the dripping water in the cave presents a detailed record of a mega-drought that followed a dramatic climatic change washing away ancient civilizations of Egypt, Greece, Syria, Palestine, the Indus Valley, Mesopotamia and the Yangtze River Valley.
The Need To Define The “Meghalayan Age”
With Earth’s recorded history divided into a period, eon, era, epoch and age, the age is the smallest unit of geographical time and epoch is the reference point from which the origin of an era is measured.
In order to understand the Meghalayan Age, we need to recognize the state of the longer period known as the Holocene Epoch which started around 11,700 years ago reflecting the dramatic warming that meant the exit of the last ice age.
According to the International Commission on Stratigraphy, the Holocene Epoch is itself subdivided into three stages.
a. The Meghalayan age is the youngest stage from 4,200 years to the present beginning with a drought causing the demise of many ancient civilizations relying on agriculture.
b. The severe drought in many low altitude regions followed by increased precipitation in the high altitude regions was likely caused by the shifts in ocean and atmospheric circulations.
c. The middle stage known as the Northgrippian runs from 8,300 years ago up to the start of the Meghalayan Age generated by the abrupt cooling accounting for the increased volumes of freshwater from melting glaciers in Canada up to the North Atlantic causing a primal shift in ocean currents.
d. The oldest phase is the Greenlandian justifying the exit from the ice age.
The Chemical Signal Found In The Cave
The classification of the geological period is based on the exhaustive cross-examination of the sedimentary deposits, ice cores and deposits below the seafloor that preserve the chemical composition citing dramatic changes on earth taking place.
Following the similar analysis trail of ice cores from Greenland laying the foundation of the Greenlandian and Northgrippian ages, the global proof corroborating the presence of the new age is the persistence of isotopes of oxygen atoms found in the layers of stalagmite growing from the floor of Mawmluh Cave in Meghalaya.
According to Mike Walker of the University of Wales (UK) who led the proposal team for the division of the new age, the isotopic shift meant a 20-30% decrease in monsoon rainfall.
Studying the particular way oxygen atoms changed, a substantial weakening of the rainfall forced by severe drought was suggested linking the Meghalayan age to a cultural event- the blatant end of many thriving civilizations.
The Debate Over The Meghalayan Age
The introduction of the Meghalayan Age has drawn fire from scientists around the world who believe the new geographic slice of time to be in contention with the concept of new Epoch called the Anthropocene.
The concept states that the intervention of humans on Earth’s chemistry and climate has cut short the 11,700-year-old Holocene Epoch ushering in the “Great Acceleration” referring to the period that started around the 1950s.
The Great Acceleration refers to the number of chemical and socio-economic changes such as concentrations in the air of Carbon dioxide, methane and stratospheric ozone, surface temperatures, population growth, tropical forest loss etc that kick off in the mid-century.
The Meghalayan age is said to impact only the civilizations in the Middle-East, India, China, and North-Africa barring out the civilizations existing in Northern Europe and America which is a signal that the episodes affected were not entirely global in scope.
But there is no denying that the stalagmites captured in the cave have preserved a high-resolution record signifying a major event in Earth’s history.