clock of eras

This history video lesson is designed for 6 to 12-year-old children. The video lesson talks about the formation and development of the planet Earth and how life existed on it, using the analogy of a circular clock. The 12-hour clock represents the various eras from the Earth’s birth to the present.

This Montessori video lesson allows the child to get a better understanding of the inception of the planet and the eras that led to its development.

What is the Clock of Eras?

A clock of eras is a graphic aid used to visualize the geologic time Earth has taken to achieve its current state.

The Clock of Eras represents the entire history of the Earth. It is presented as a pie chart which serves as an easy way for the children to understand the big picture of the timeline. It’s a twelve-hour clock covering the Hadean to Cenozoic Era. Let us discuss each era:

Headen Era

The Headen Era is represented by the first hour and fifty minutes of the Clock (4 to 4.5 billion years ago). It is represented as black color. At that time, the Solar System was forming out of spinning clouds of dust and gases. The sun started emitting light and heat, and Earth took shape. Later, as the Earth cooled, its mass increased. 

The Archean Era

The Archean era is represented by 3 hours 28 minutes of the clock ( 2.5 to 4 billion years ago). During this period, the Earth’s crust solidifies, oceans form, tectonic activity begins. The atmosphere has no oxygen and is filled with hydrogen, methane, and ammonia. The first stage of early life began in this era. It is represented as a yellow color.

The Proterozoic Era

The proterozoic era is represented by 5 hours 12 minutes (2.5 Billion To 541 Million Years ago). In this era, Earth started supporting life. Animals and life forms happened during this time on our timeline of life. During this time, bacteria and protozoa began to appear in the sea and land. They led to the birth of invertebrates and vertebrates.  

The Paleozoic Era

The Paleozoic era is represented by 47 minutes of the clock. In this era, plants and animals moved onto land and learned to co-exist. It is also the time when mass extinction happened and eliminated most of the species of life that existed.

The Mesozoic Era

The Mesozoic era is represented by 29 minutes. In this era, plants and animals adapted to life on land. It is also known as the age of dinosaurs because dinosaurs and reptiles dominated this era. The word Mesozoic comes from words; mezzo means middle, and zoic means animals. 

The Cenozoic Era

The Cenozoic era is represented by 10 minutes and is a red color stripe. The word Cenozoic comes from Sano, which means recent, and zoic refers to animals. It is the era when all the gigantic mammals live like the woolly mammoths and saber-toothed Tigers. The Cenozoic era is also called the “Age of Flowering Plants, Insects and Birds,” as many known species took birth in this era. Humans also live in the most recent period of the Cenozoic era. 

Watch the video to know more about the history of the Earth

Interested to know how life came into existence? Watch the great lesson “The coming of life.”

For more cultural video resources, click here.

Video Created by: Justine McNeilly


  • culture
  • Elementary
  • English
  • history