Podcast
Questions and Answers
What term describes the downhill movement of a large mass of rocks or soil due to gravity?
What term describes the downhill movement of a large mass of rocks or soil due to gravity?
Which natural force primarily drives the flow and movement of glaciers?
Which natural force primarily drives the flow and movement of glaciers?
What is the primary agent of erosion and sediment transport on Earth?
What is the primary agent of erosion and sediment transport on Earth?
What land feature is formed at the point where rivers enter oceans or lakes and deposit sediment?
What land feature is formed at the point where rivers enter oceans or lakes and deposit sediment?
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Which of the following processes is related to landform change in desert areas?
Which of the following processes is related to landform change in desert areas?
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What process is described as the breaking down of rock without changing its composition?
What process is described as the breaking down of rock without changing its composition?
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Which of the following substances can contribute to chemical weathering?
Which of the following substances can contribute to chemical weathering?
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What term describes the process of moving weathered material from one location to another?
What term describes the process of moving weathered material from one location to another?
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Which factor is known to speed up chemical weathering processes?
Which factor is known to speed up chemical weathering processes?
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What is the result of physical weathering?
What is the result of physical weathering?
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What role can plant roots play in physical weathering?
What role can plant roots play in physical weathering?
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What is sediment formed from weathered rock typically composed of?
What is sediment formed from weathered rock typically composed of?
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How does erosion differ from deposition?
How does erosion differ from deposition?
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Study Notes
Grade 8 Changing Earth's Surface - Chapter 3 Section 2
- The processes that slowly break down mountains are often not noticeable during a person's lifetime.
- Copy notes into notebook, leaving space for additions.
- Answer review questions using the textbook if needed.
- Watch videos, noting any interesting information. You can adjust playback speed.
Essential Questions
- What is the difference between physical and chemical weathering?
- How do water, ice, and wind shape Earth's surface?
Breaking Down Earth Materials
- Processes breaking down mountains are called weathering.
- Weathering involves mechanical and chemical processes.
- The material formed from broken rocks is sediment.
- Sediment can take forms like rock fragments, sand, silt, and clay.
Types of Sediment
- Sediment types are determined by texture, composition, and history of transport, intensity of weathering, and source rock properties.
Physical Weathering
- Physical weathering breaks down rocks without changing their composition.
- Examples include: plate movements, boulders rolling off cliffs, cracks in rocks widening by repeated freezing and thawing of water, plant roots prying open rocks (root pry).
Chemical Weathering
- Chemical weathering alters the rock's composition.
- Examples include: minerals dissolving in slightly acidic water (like rainwater), other minerals reacting with carbon dioxide or oxygen in the air.
- Abundant water and warmer temperatures speed up chemical weathering.
Moving Earth Materials
- Erosion is the movement of weathered material (sediment) from one location to another.
- Deposition is the laying down or settling of eroded material.
- Mass wasting is downhill movement of rocks or soil due to gravity.
- A landslide is a type of mass wasting on steep slopes.
- Water, wind, ice, and gravity move sediment.
- Faster water moves larger pieces of sediment than slower water.
- Sediment is deposited on the sides of rivers as water slows.
- Rivers entering oceans/lakes deposit sediment to form deltas.
- Wind erosion is important in deserts, creating landforms like sand dunes and ripples.
Ice
- Glaciers are large masses of ice that move slowly across Earth's surface.
- Gravity causes glaciers to flow downhill, weathering the rocks beneath.
- Glaciers pick up sediment as they flow and deposit it when they melt.
- Examples include moraines.
Glaciers and Cape Cod
- Glaciers affected the landscape by erosion and deposition, shaping the areas they covered
What about Yosemite?
- Yosemite's landscape was affected by glaciers
Plate Tectonics
- Plate tectonics explains many Earth surface features and the processes that occur on it.
Climate
- Climate affects the processes that move Earth material.
Review Questions
- How is weathering related to sediment?
- What processes break rock into smaller pieces?
- What are the differences between chemical and physical weathering?
- What forces cause rock to move downhill?
- What causes most erosion on Earth?
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