Questions and Answers
What is the main principle behind relative dating?
What is the term for molten rock that invades preexisting rock layers?
What is the term for an intrusion that forms in a horizontal crack or between layers in a rock?
Why is it important to consider disruptions within the layers when using relative dating?
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What is the term for a type of intrusion that forms a dome shape?
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What is a fault in rocks?
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What can be concluded about the order of events in the diagram?
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What is the relative age of the layers in the diagram?
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What can be compared to faults in the natural world?
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What can be said about the intrusion in the diagram?
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What is the purpose of relative dating in geology?
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What is the similarity between the layers of a jawbreaker and the layers of rock beneath the Earth's surface?
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What happens to a small ball of candy when it is rolled in liquid sugar and left to dry?
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Why is the concept of relative dating familiar to most people?
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What can scientists determine from looking at the layers of rock using relative dating?
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Study Notes
Layers Within the Earth
- The Earth's rock layers are similar to the layers of a jawbreaker candy, with each layer representing a record of time passing.
- The deeper you go, the farther back in history you are.
Relative Dating
- Relative dating is a method used by scientists to determine the order of events without using actual ages.
- It's a way to compare rocks and rock layers by using what is immediately around them.
- The general rule of thumb is that older layers are found at the bottom, and newer layers are found at the top.
- Relative dating only gives a sequence of what happened before or after some other event, not an actual date the event happened or a true age.
Fossil Dating
- Fossils found in deeper layers are usually older than those found in upper layers.
- Paleontologists use relative dating to determine when in Earth's history organisms found buried in rock layers may have been alive.
Disruptions Within the Layers
- Rocks don't always form in layers; sometimes they melt upward through existing rock.
- An intrusion is when molten rock invades preexisting layers.
- Intrusive rocks can form volcanoes, batholiths, sills, dikes, or laccoliths.
- Faults can also disrupt the layers of rocks, causing them to shift and change appearance.
Batholiths and Other Intrusions
- A batholith is a type of intrusion that forms when magma cools beneath the surface.
- A sill is a type of intrusion that forms within a horizontal crack or between layers in a rock.
- A dike is a type of intrusion that forms in a vertical crack.
- A laccolith is a type of intrusion that forms in a dome shape.
Faults
- A fault is a break in the rocks where the layers can slide past each other.
- Faults can make it difficult to understand which strata were previously connected.
- Faults can cause layers to shift and change appearance.
Analyzing Strata
- By analyzing strata, scientists can determine the order of events and the age of layers relative to each other.
- Intrusions and faults can provide clues about the history of the layers.
- By looking at a diagram of strata, scientists can reconstruct the sequence of events and the relationships between different layers.
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Description
Learn about the different layers that make up our planet, from the crust to the core. Explore the structure and composition of each layer and how they interact with one another.