Precambrian
The Precambrian is the earliest part of Earth's history, spanning from the formation of the Earth about 4.6 billion years ago to the beginning of the Cambrian period, approximately 541 million years ago. It is divided into three eons: the Hadean, Archean, and Proterozoic eons.
Hadean Eon (4.6 - 4.0 billion years ago)
The Hadean eon represents the earliest stages of Earth's formation. During this time, the Earth was bombarded by meteorites and experienced intense volcanic activity. The atmosphere and oceans were just beginning to form, and the surface was largely molten.
Archean Eon (4.0 - 2.5 billion years ago)
The Archean eon marks the appearance of life on Earth. Early prokaryotic organisms, such as bacteria and archaea, emerged in the oceans. The atmosphere contained little oxygen, and the continents were forming through volcanic activity and tectonic processes.
Proterozoic Eon (2.5 billion - 541 million years ago)
The Proterozoic eon is characterized by the development of more complex life forms, including eukaryotic cells and multicellular organisms. The supercontinent Rodinia formed and later broke apart, leading to the diversification of life. Oxygen levels in the atmosphere gradually increased, leading to the Great Oxygenation Event.
Study Guide
- What are the three eons of the Precambrian?
- Describe the conditions during the Hadean eon.
- What is significant about the Archean eon in the context of life on Earth?
- How did the Proterozoic eon contribute to the diversification of life?
- Explain the importance of the Great Oxygenation Event.
[Precambrian] Related Worksheets and Study Guides:
.◂Chemistry Worksheets and Study Guides High School. Elements - Set I
Worksheet/Answer key
Worksheet/Answer key