Podcast
Questions and Answers
Why are fossils typically not found within igneous rocks?
Why are fossils typically not found within igneous rocks?
- Igneous rocks primarily form in environments devoid of life; therefore no organic material is present.
- The high temperatures involved in the formation of igneous rocks destroy any fossil remains. (correct)
- The rapid cooling process of igneous rocks prevents the incorporation of fossil materials.
- Igneous rocks usually form deep within the Earth's crust, far from where fossils are commonly found.
How does the rate of cooling affect the crystal size in igneous rocks?
How does the rate of cooling affect the crystal size in igneous rocks?
- Faster cooling results in smaller crystals because there is less time for crystals to form. (correct)
- The rate of cooling does not affect crystal size; it solely depends on the rock's chemical composition.
- Slower cooling results in smaller crystals as the molecules have less energy to arrange themselves.
- Faster cooling results in larger crystals due to increased thermal energy.
Which of the following best illustrates physical weathering via temperature change (onion skin)?
Which of the following best illustrates physical weathering via temperature change (onion skin)?
- The daily cycle of heating and cooling causing a rock's outer layers to peel off. (correct)
- The expansion of freezing water cracking a rock.
- Plant roots growing into rock crevices and splitting the rock apart.
- Acid rain gradually dissolving limestone rock formations.
Why is rain naturally slightly acidic?
Why is rain naturally slightly acidic?
What is the primary difference between physical and chemical weathering?
What is the primary difference between physical and chemical weathering?
How does biological weathering contribute to the breakdown of rocks?
How does biological weathering contribute to the breakdown of rocks?
What is the role of compaction in the formation of sedimentary rocks?
What is the role of compaction in the formation of sedimentary rocks?
Which of the following processes occurs first in the formation of sedimentary rocks?
Which of the following processes occurs first in the formation of sedimentary rocks?
Flashcards
Igneous Rocks
Igneous Rocks
Rocks formed from cooled and solidified molten rock (magma or lava).
Extrusive Igneous Rocks
Extrusive Igneous Rocks
Igneous rocks formed on the Earth's surface from lava; cool quickly, forming small crystals.
Intrusive Igneous Rocks
Intrusive Igneous Rocks
Igneous rocks formed beneath the Earth's surface from magma; cool slowly, forming large crystals.
Physical Weathering
Physical Weathering
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Chemical Weathering
Chemical Weathering
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Freeze-Thaw Weathering
Freeze-Thaw Weathering
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Temperature Change Weathering
Temperature Change Weathering
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Deposition
Deposition
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Study Notes
- There are 3 types of rocks: Igneous, metamorphic, and sedimentary.
Igneous Rocks
- Igneous rocks are associated with volcanoes.
- They are "fire-born," forming from the cooling and solidification of molten rock.
- Igneous comes from "ignis", which is Latin for "fire".
- Molten rock is magma until erupted, when it becomes lava.
- Two types: intrusive and extrusive.
- Extrusive rocks form on the surface from lava, cooling quickly and having fewer crystals.
- Intrusive rocks form below the Earth's crust, cooling slowly and having more crystals.
- Igneous rocks do not contain fossils because the heat destroys them.
- They often contain multiple mineral deposits in various sizes.
- Igneous rocks usually have a course or glassy texture.
- Usually do not react to acids.
Weathering
- Two types of weathering: physical and chemical.
- Physical weathering breaks rocks into smaller pieces without changing composition.
- Chemical weathering changes the rock's composition.
- Types of Physical Weathering:
- Temperature change (freeze): Water expands when frozen, breaking the rock.
- Temperature change (onion skin): Rocks expand during the day when heated by the sun, and contract at night when cooled which, over time weakens and cracks the rock.
- Biological weathering: Plant roots wedge rocks apart as they grow in cracks.
- Chemical Weathering:
- Acid rain: Carbon dioxide mixes with rain, creating a substance that breaks down rocks.
Sedimentary Rocks
- Weathering and erosion lead to sediment formation, which forms sedimentary rocks.
- The process:
- Deposition: Sediments, dead animals, and plant material settle in horizontal layers.
- Compaction: Sediment grains are squashed together over millions of years.
- Cementation: Minerals in solutions precipitate and cement the grains together.
- Sedimentary rocks form in layers called strata and can containing fossils.
- Three types of sedimentary rocks:
- Clastic: Formed by compaction and cementation of rock sediment.
- Organic: Formed by compaction and cementation of dead organic material.
- Chemical: Formed when water transports and re-deposits material.
Metamorphic Rocks
- Metamorphic rocks form when rocks are exposed to heat and pressure.
- There are two types of metamorphism: regional and contact.
- Regional metamorphism:
- Occurs slowly over large areas.
- Rocks are buried under other rock layers, exposing them to heat and pressure.
- Contact metamorphism:
- Occurs when molten rock (magma or lava) rises and contacts surrounding rocks.
- In this case, there is more heat than pressure involved.
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Description
This lesson covers igneous rocks and weathering. It defines igneous rocks as those formed from cooled magma or lava, distinguishing between intrusive and extrusive types. It also differentiate between physical and chemical weathering.
