How long was the Precambrian era?
4,000
4,000,000
4,000,000,000
4
The correct answer and explanation is:
The correct answer is 4,000,000,000 years.
The Precambrian era is the longest geological time span in Earth’s history, lasting approximately 4 billion years. It began with the formation of the Earth around 4.6 billion years ago and ended about 541 million years ago with the start of the Cambrian period, which marks the beginning of the Phanerozoic Eon.
The Precambrian era is divided into three eons:
- Hadean Eon (about 4.6 billion to 4 billion years ago): This is the time when the Earth was forming. The planet was molten, and the atmosphere was hostile to life. The Earth’s surface eventually cooled enough to form a solid crust, and the first oceans began to appear.
- Archean Eon (about 4 billion to 2.5 billion years ago): Life began in the form of simple microorganisms, like bacteria and archaea. These organisms formed in the oceans, and some of them even contributed to early photosynthesis, which started to release oxygen into the atmosphere.
- Proterozoic Eon (about 2.5 billion to 541 million years ago): This period saw significant development in life forms, with the first multicellular organisms appearing. The atmosphere began to accumulate more oxygen due to photosynthesis, leading to what is known as the “Great Oxygenation Event.” This eon also witnessed the formation of supercontinents and the emergence of early eukaryotic cells, the building blocks for more complex life.
The Precambrian era, although dominated by simple life forms, laid the foundation for the more complex life forms that would eventually flourish in the Cambrian period. Most of Earth’s geological history, including the origins of life itself, falls within this era.