Epoch (geology) facts for kids

An epoch in geology is a way scientists divide Earth's long history into smaller chunks of time. Think of it like chapters in a very long book about our planet! An epoch is a part of a period, which is itself part of an era.

For example, the Cainozoic era (which means "new life") is the time we live in now. It's split into three main periods: the Palaeogene, the Neogene, and the Quaternary. Each of these periods is then broken down into even smaller epochs.

Understanding Earth's Time Scale

Scientists use a special calendar called the Geologic Time Scale to organize Earth's history. This scale helps us understand when different events happened, like when dinosaurs lived or when mountains formed.

How Geologic Time is Divided

The biggest divisions of geologic time are called eons. Eons are then split into eras, which are further divided into periods. Periods are made up of epochs, and epochs can even be broken down into smaller ages.

Here's a simple way to think about it:

• Eon (like a very long book series)
  • Era (like a book in the series)
    • Period (like a chapter in the book)
      • Epoch (like a section within a chapter)

* Age (like a paragraph in a section)

Who Decides These Names?

The names and divisions of geologic time are decided by a group of experts called the International Union of Geological Sciences (IUGS). This organization has a special team, the International Commission on Stratigraphy. They work to make sure everyone around the world uses the same names for these time units.

Their main goal is to clearly define the global units of the International Chronostratigraphic Chart. These units are the foundation for the International Geologic Time Scale, which helps geologists communicate clearly about Earth's past.

Epochs of the Mesozoic Era

The Mesozoic era is famous for being the "Age of Dinosaurs." It includes three main periods, each with its own epochs, though the epochs are not as commonly discussed for this era as they are for the Cenozoic.

• Triassic Period
  • Lower Triassic
  • Middle Triassic
  • Upper Triassic
• Jurassic Period
  • Lower Jurassic
  • Middle Jurassic
  • Upper Jurassic
• Cretaceous Period
  • Lower Cretaceous
  • Upper Cretaceous

Epochs of the Cainozoic Era

The Cainozoic era, which started about 66 million years ago, is often called the "Age of Mammals." This is the era we are currently in.

Palaeogene Period

The Palaeogene period began right after the dinosaurs disappeared. It saw the rise of many new types of mammals.

• Palaeocene Epoch
• Eocene Epoch
• Oligocene Epoch

Neogene Period

The Neogene period continued the development of mammals and saw big changes in Earth's climate and landscapes.

• Miocene Epoch
• Pliocene Epoch

Quaternary Period

The Quaternary period is the most recent period, covering the last 2.58 million years. It includes the Ice Ages and the time when humans developed.

• Pleistocene Epoch (often called the Ice Age epoch)
• Holocene Epoch (the epoch we live in now, starting about 11,700 years ago)

You might sometimes hear about the "Tertiary" period. This term used to include the Palaeogene and Neogene periods. However, scientists no longer use "Tertiary" because they decided to split it into these two separate periods. This change led to some debate, but it helps make the geologic time scale more precise.

See also

In Spanish: Época geológica para niños