Geologic Time Scale
Grade 8 · Science · Earth and Space · Wyoming, USA
Lesson Summary
Learn how scientists divide Earth's 4.6-billion-year history into time periods.
Explanation
The geologic time scale divides Earth's history into eons, eras, periods, and epochs based on major events in the fossil record and geology. The Precambrian covers most of Earth's history, from formation to about 540 million years ago. The Paleozoic, Mesozoic, and Cenozoic eras follow, each defined by the life forms that dominated. Dinosaurs ruled during the Mesozoic, and mammals dominate the current Cenozoic era. This timeline helps scientists organize billions of years of change.
Practice Questions
Q1: Which era is known as the age of dinosaurs?
Answer: The Mesozoic era, which lasted from about 252 to 66 million years ago.
Q2: What major event marks the boundary between the Mesozoic and Cenozoic eras?
Answer: A mass extinction event, likely caused by an asteroid impact, which wiped out the dinosaurs about 66 million years ago.
Q3: Why is the Precambrian the longest division of geologic time?
Answer: It covers about 4 billion years, from Earth's formation to the explosion of complex life about 540 million years ago.
People Also Ask
What is Geologic Time Scale in Grade 8 Science?+
Geologic Time Scale is a lesson in the Earth and Space chapter of Grade 8 Science. It is part of the Wyoming, USA school curriculum and covers key concepts that students need to understand at this level.
What grade level covers Geologic Time Scale?+
Geologic Time Scale is taught in Grade 8 as part of the Science curriculum in Wyoming, USA.
How can I help my child with Earth and Space in Science?+
Start with the lesson summary and explanation on this page. Practice the questions provided, then use TutorTom for personalized, step-by-step help with Earth and Space topics.