Geologic Time

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What is Relative Age?

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Relative Age is the age of an object or event in comparison to another object or event. It helps to determine whether something is older or younger without providing a specific numerical age.

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What is Absolute Age?

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Absolute Age is the actual age of an object or event, often expressed in years. It can be determined through methods like radiometric dating.

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What is Radiometric Dating?

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Radiometric Dating is a technique used to date materials such as rocks or carbon by comparing the abundance of a radioactive isotope to its decay products.

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What is the Law of Superposition?

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The Law of Superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

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What are Index Fossils?

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Index Fossils are fossils of organisms that were widespread but only existed for a short period of geological time. They are used to date and correlate the age of rock layers.

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What is Precambrian Time?

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Precambrian Time is the earliest part of Earth's history, covering about 88% of geological time, before the Cambrian period.

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What is the Paleozoic Era?

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The Paleozoic Era is a major era in Earth's history that lasted from about 541 to 252 million years ago, known for the development of fish, amphibians, and reptiles.

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What is the Mesozoic Era?

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The Mesozoic Era, known as the age of reptiles, lasted from about 252 to 66 million years ago and is famous for the dominance of dinosaurs.

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What is the Cenozoic Era?

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The Cenozoic Era is the current geological era, beginning about 66 million years ago, characterized by the rise of mammals and birds.

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What are Cross-Cutting Relationships?

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Cross-Cutting Relationships is a principle stating that if a geological feature cuts through another, the feature that has been cut is older.