How Do Scientist Determine When an Era Begin and When it Ends?

February 15, 2024

How do scientist determine when an era begins and when it ends?

An era is a large chunk of time on Earths geologic timeline. When one era ends, a new era starts and the old one fades into memory. Scientists use a variety of techniques to decode the planets super long history. This includes stratigraphy, fossil analysis, radiometric dating, and the study of global events. The most important method scientists have for determining when an era begins and ends is the fossil record. The record of past organisms shows us when life radically changed. These drastic changes are called mass extinctions. During mass extinctions about 90 percent of all living things die. This causes the remaining living things to evolve and adapt.

Geologists use this information to create the geologic time scale, which is a calender of Earths history. This is a useful tool because it allows scientists to see the overall patterns of life in the planet. It also helps scientists to understand what caused the eras to begin and end.

The earliest geologic eras are the Eocene and Oligocene. These eras mark the beginning of an ice age and a period of global climate change. The ice ages were caused by a dramatic cooling of the planets atmosphere. Scientists think that the change in climate was caused by an asteroid strike near the end of the Mesozoic Era 65 million years ago. This was the big event that killed the nonavian dinosaurs and ushered in our current era, the Cenozoic.


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