IUGS Commission on Stratigraphy
Stalagmite indicating the beginning of the Meghalayan ageIUGS Commission on StratigraphySome 4,200 years ago, Earth’s climate cooled, altering global rainfall patterns. As a result, a 200-year drought hit the great agricultural civilizations of the Mediterranean, the Middle East, and Asia, leading some, such as Mesopotamia, to collapse. This global cooling and subsequent drought left its mark on rocks and sediments all over the planet, including the stalagmites found in a cave in the state of Meghalaya, in northern India. A team led by Mike Walker, from the University of Wales, UK, has suggested that the marks on these stalagmites signify the beginning of a new chapter in Earth’s history: the Meghalayan age, in which we currently live. The proposal was approved by the International Union of Geological Sciences (IUGS) on June 14. Geologists divide the 4.6 billion years of Earth’s history into time periods based on global changes in rocks and sediments, known as geological eras. Each era is separated into periods, and each period is divided into epochs, which are split into ages. The most recent era, the Cenozoic, began 65 million years ago with the extinction of dinosaurs, and has three periods. The current period, known as the Quaternary, began 2.6 million years ago when glaciation affected the evolution of mammals, and contains two epochs: the Pleistocene and the Holocene. The proposal approved by the IUGS divides the Holocene into three ages: the Greenlandian, Northgrippian, and Meghalayan.
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