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The official history of the Earth has a new chapter. Geologists have just ranked the last 4,200 years as a definite age in the history of our planet. The new geological age is called Megalaya Age or Megalayense and began when a great drought affected many civilizations.
The new classification means that the famous International Chronostratigraphic Charter, the famous diagram of the geological history of the Earth taught, must be updated.
The decision announced this week by the International Stratigraphy Commission of the International Union of Geological Sciences has caused surprise and controversy in the scientific community. Several researchers say that there was not enough debate since a study raised the possibility of Megalayense seven years ago.
200 Years of Drought
Geologists divide the 4.6 billion years of the Earth's history. temporary stripes. Each corresponds to a significant event, such as the separation of continents, dramatic changes in climate or the emergence of certain species of plants or animals.
Currently, we live in the geological Holocene, which includes everything that has happened since 11,700 years ago, when a great warming ended the last ice age, but the Holocene itself was now divided into ages by the International Stratigraphy Commission.
Each of these ages marks dramatic changes in the climate of the planet. The most recent, Megalayense, has grown from 4200 years to the present day and began with a drought, the effects of which have been felt for 200 years. The drought has caused the collapse of civilizations and migrations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus Valley and the Yangtze River.
Scientists believe that this devastating atmospheric drought In addition to the Megalayense, the other two Holocene subdivisions are Greenlandic (11,700-8,300 years ago) and Norgripian (8,300-4,200 years old).
These phases were defined by global climatic changes recorded by isotopic markers on ice cores from two different holes in central Greenland at depths of 1,492 and 1,228 meters, respectively.
The other name, Norgripian, refers to one of those Greenlandic polls called NGRIP1 (North Greenland Ice Core Project No. 1). Megalaya, a state in India
For a phase to be classified as distinct, it must reflect some change in overall impact and be associated with a rock or sediment that clearly shows it. The limit, for example, that 66 million years ago marked the passage from Cretaceous to Tertiary can be observed in traces of the element iridium in sediments.
This metal was scattered around the planet after the impact of the asteroid. In the case of Megalayense, the best record can be seen in layers of stalagmites or mineral deposits in the caves of Megalaya, a state in northeastern India.
"Now it's official"
Questioning about the impact of climate change used in the new classification and ensuring that she is premature.
Several geologists also questioned the approval of new subdivisions while discussing a possible new phase that reflects the impact of humans on the planet
This phase was provisionally called Anthropocene and is currently being studied what would be the precise definition and its beginning.
"After the study seven years ago and the consideration of several committees, they make a sudden announcement and change the pattern" Mark Maslin, professor of geography at University College London and l & # 39; 39, one of the leading scientists in the debate on the Anthropocene, told the BBC.
"Now, it's either fici, we're in a new age, who would say it?" We now have definitions that (& mldr;) can go against what most scientists see as the most significant change on Earth in the last 10,000 years. "
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