Geologic Time Scale

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What is the Geologic Time Scale?

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A system of chronological dating that relates geological strata to time, used by geologists and other Earth scientists to describe the timing and relationships of events in Earth's history.

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What is an igneous intrusion?

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A body of igneous rock that forms when magma cools and solidifies within pre-existing rock layers.

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What is a trace fossil?

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A fossil that records the activity of an organism, such as footprints, burrows, or feces, rather than the organism itself.

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What is catastrophism?

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The principle that Earth's landscape has been shaped by a series of sudden, short-lived, and violent events, such as meteor impacts or volcanic eruptions.

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What is an index fossil?

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A fossil that is used to define and identify a particular time period in the geologic time scale, typically widespread and existed for a short duration.

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What does carbonization mean in fossilization?

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A process where organic material is reduced to a carbon residue, preserving the outline of the organism.

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What is the significance of finding marine fossils in freshwater streams?

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It suggests that the area may have been underwater in the past, indicating changes in Earth's geography over time.

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What is the difference between original fossils and cast fossils?

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Original fossils are the actual remains of the organism, while cast fossils are replicas formed when a mold of the organism is filled with sediment or minerals.

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What is the role of plate tectonics in Earth's history?

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Plate tectonics explains the movement of Earth's lithospheric plates, leading to the formation of mountains, earthquakes, and the distribution of continents and oceans.

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What is an example of a significant event in Earth's history that supports the theory of catastrophism?

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The impact of a huge meteor hitting Earth, which is believed to have contributed to the extinction of the dinosaurs.