New Ruling Decides the Boundaries of Earth’s History
The decision has been made by the International Commission on Stratigraphy (ICS), the authority of geological science has moved to end decades of dispute to formally declare when the Quaternary period, covering both the ice age and the time began to use primitive tools, began.
In the 18th century history of the Earth is divided into four periods, Primary, Secondary, Tertiary and Quaternary. Although the first two have been renamed Paleozoic and Mesozoic, respectively, the latter have remained in use by scientists from more than 150 years. There was a lengthy discussion on the position and state of Quaternary geologic time scale and intervals of time it represents.
“It has long been agreed that the Quaternary Period limitation should be placed at the first sign of cooling of global climate,” said Professor Philip Gibbard. “What we have achieved is the definition of the limits of the Quaternary international recognition and a fixed point representing a natural event, the beginning of ice ages on a global scale.
The controversy about exactly when the Quaternary Period began has been debated for decades, attempts in 1948 and 1983 to define the era. In 1983 the limit was set at 1.8 million years, a move that sparked the argument in the community of earth sciences at this point was not a “natural boundary” and had no particular geological significance.
So far it has been felt in the scientific community that the boundary should be located before, in a time of major change in the Earth’s climate system.
“For practical reasons such boundaries ideally as easy as possible to identify worldwide. The new limit of 2.6 million years is just that,” concluded Gibbard, “therefore, we are delighted to finally achieve our goal of eliminating the limit on this first point. ”
“The decision is very important to the scientific community working in the field,” said Journal Editor Professor Chris Caseldine. “It gives us a point in geological time, when it is actually moved into a new age-like weather reconnaissance geological present.
More information: Gibbard.P, Head.M Formal ratification of the Quaternary System/Period and the Plestocene series/Eoch with a base at 2.58 Ma, Journal of Quaternary Science, Wiley-Blackwell, 2009; DOI: 10.1002/jqs.1338
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