Geological era: What is it?

Trees surround Crawford Lake in Milton, Ontario., on Monday, July 10, 2023. A team of scientists is recommending the start of a new geological epoch defined by how humans have impacted the Earth should be marked at the pristine Crawford Lake outside Toronto in Canada.
| Photo Credit: AP

Our planet is more than four billion years old – a staggering amount of time for humans to contemplate. To ease this task, experts have divided earth’s history into pieces of time, called aeons, eras, periods, and epochs.

These divisions in Earth’s geological timescale demarcate key geologic events and the appearance (or disappearance) of notable forms of life. It all began with the creation of the earth’s crust and continued with the appearance of plants, birds and animals, their ceaseless evolution making a mark in some way on their time.

Broadly, there are four geological eras. The Precambrian Era began 4.6 billion years ago, with the formation of our planet and the emergence of the first life forms. The Palaeozoic Era lasted from 541 million to 252 million years ago, and was characterised by the evolution of complex life, including fish, plants, insects, and amphibians.

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The Mesozoic Era came next, lasting from 252 million years until 66 million years ago. This was the age of dinosaurs, together with the first appearance of birds and flowering plants towards the denouement. Finally came the Cenozoic Era, which began 66 million years ago and continues to this day, distinguished by the rise of modern animals.

Today, scientists around the world are locked in a debate about whether we are currently in a new geological time period, dubbed the “Anthropocene”, marked by the oft-devastating effects of human presence on earth.