The Age of Earth
The estimated age of Earth
What is about 4.6 billion years?
The largest division of geological time.
What is an eon?
A diagram showing rock layers and their ages.
What is the geologic column?
Dating method that places events in order
What is relative dating?
Fossils that help date rock layers
What are index fossils?
Evidence used to determine Earth's age.
What is radiometric dating of rocks and meteorites?
Time unit smaller than an eon but larger than a period.
What is an era?
A sequence of rock layers arranged by age.
What is the geologic column?
Dating method that gives a numerical age
What is absolute dating?
Fossils useful because they lived for a short time
What are index fossils?
Earth formed during this Eon.
What is the Hadean Eon?
Era known as the "age of reptiles".
What is the Mesozoic Era?
The oldest rock layers are found where in the column?
What is at the bottom?
Dating igneous rocks using radioactive decay
What is radiometric dating?
Era when most modern life forms appeared
What is the Cenozoic Era?
Approximate age of Earth in billions of years.
What is about 4.6 billion years old?
Time unit between era and epoch.
What is a period?
Why the geologic column is not complete in one location.
What is erosion or non-deposition?
Uses half-lives of isotopes
What is radiometric dating?
Era known as the “Age of Mammals”
What is the Cenozoic Era?
why meteorites help determine Earth's age.
What is they formed at the same time as Earth?
approximate age of the Paleozoic Era.
What is about 541–252 million years ago?
What unconformities represent in the column
What are gaps in the rock record?
Why absolute dating is more precise
What is it gives exact numerical ages?
Period when dinosaurs went extinct
What is the Cretaceous Period?