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Questions and Answers
What are the two main categories of geological processes?
What are the two main categories of geological processes?
Epigene processes and Hypogene processes
What are the four processes that work together to modify the Earth's surface?
What are the four processes that work together to modify the Earth's surface?
Mechanical weathering alters the chemical composition of rocks and minerals.
Mechanical weathering alters the chemical composition of rocks and minerals.
False
Which of the following is NOT a major process that causes mechanical weathering?
Which of the following is NOT a major process that causes mechanical weathering?
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What type of weathering occurs when air and water chemically react with rock, altering its composition and mineral content?
What type of weathering occurs when air and water chemically react with rock, altering its composition and mineral content?
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What are three important processes of chemical weathering?
What are three important processes of chemical weathering?
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Which mineral dissolves rapidly in water and is rare in moist environments?
Which mineral dissolves rapidly in water and is rare in moist environments?
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Acid rain can damage ancient sculptures and historical monuments, leading to pitting and rounding of features.
Acid rain can damage ancient sculptures and historical monuments, leading to pitting and rounding of features.
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What are the formations that are formed in limestone caves as a result of dissolved ions carried away by flowing water?
What are the formations that are formed in limestone caves as a result of dissolved ions carried away by flowing water?
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Hydrolysis is a process where water reacts with a mineral to form a new mineral with water incorporated into its crystal structure.
Hydrolysis is a process where water reacts with a mineral to form a new mineral with water incorporated into its crystal structure.
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What mineral resists weathering due to its pure silica composition and grain structure?
What mineral resists weathering due to its pure silica composition and grain structure?
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Oxidation is a process that involves the gain of electrons from a compound.
Oxidation is a process that involves the gain of electrons from a compound.
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Pure metals are abundant in the Earth's crust and occur predominantly as compounds.
Pure metals are abundant in the Earth's crust and occur predominantly as compounds.
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What mineral decomposes when it oxidizes, and is often found in minerals like olivine, pyroxene, and amphibole?
What mineral decomposes when it oxidizes, and is often found in minerals like olivine, pyroxene, and amphibole?
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What are the two types of weathering that work together to break down rocks?
What are the two types of weathering that work together to break down rocks?
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Mechanical weathering can expose more surface area for chemical weathering to act upon.
Mechanical weathering can expose more surface area for chemical weathering to act upon.
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Both mechanical and chemical weathering processes contribute to spheroidal weathering, which rounds corners and edges of rocks.
Both mechanical and chemical weathering processes contribute to spheroidal weathering, which rounds corners and edges of rocks.
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What process involves the growing crystals of dissolved salt exerting forces that can widen cracks and fracture rocks?
What process involves the growing crystals of dissolved salt exerting forces that can widen cracks and fracture rocks?
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What process involves large plates or shells splitting away from rocks, similar to the layers of an onion?
What process involves large plates or shells splitting away from rocks, similar to the layers of an onion?
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Study Notes
Physical Geology - Geo 303
- Course instructor: Dr. Fares Khedr
- Department: Geology, Faculty of Science
Geological Processes
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Epigene processes: Driven by air, wind, water, glaciers, organic activity
- Examples: Denudation (weathering, erosion, transportation)
- Examples: Sedimentation (mechanical, chemical, organic)
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Hypogene processes: Driven by internal Earth processes.
- Examples: Earth movements (earthquakes, mountain building)
- Examples: Magmatic activity (volcanic eruptions, lava flow)
- Examples: Metamorphism (igneous and sedimentary rocks)
Weathering
- Definition: The decomposition and disintegration of rocks and minerals at the Earth's surface.
- Result: Formation of weathered material, which accumulates and overlies unweathered bedrock.
Erosion, Transportation, and Deposition
- Erosion: The removal of weathered rocks and minerals by moving water, wind, glaciers, and gravity.
- Transportation: The movement of eroded rock fragments from their source by flowing water, wind, ice, and gravity.
- Deposition: The settling of transported materials when the carrying agent (wind or water) slows down or loses energy, or when the agent melts (like glaciers).
- Processes discussed work together to modify the Earth's surface.
Weathering Types
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Mechanical weathering: Reduces solid rock to rubble but doesn't change the chemical composition of rocks and minerals.
- Causes: Pressure-release fracturing, frost wedging, abrasion, thermal expansion/contraction, organic activity
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Chemical weathering: Occurs when air and water chemically react with rock, altering its composition and mineral content.
- Causes: Dissolution, hydrolysis, oxidation
Mechanical Weathering Processes
- Pressure-release fracturing: Overlying rock erodes, decreasing pressure on buried rock, causing expansion and fracturing.
- Frost wedging: Water freezing in cracks expands, widening the cracks and breaking the rock apart.
- Abrasion: Mechanical wearing and grinding of rock surfaces by friction and impact (e.g., rocks tumbling in streams or glacial movement).
- Thermal expansion and contraction: Daily/yearly heating and cooling cycles cause rocks to expand and contract, leading to fracturing.
- Organic activity: Plant roots growing in cracks push rocks apart.
Chemical Weathering Processes
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Dissolution: Minerals dissolve in water, forming a solution.
- Example: Halite (rock salt) dissolves readily in water.
- Example: Calcite dissolves in carbonic acid, produced by carbon dioxide in water.
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Hydrolysis: Water reacts with a mineral to form a new mineral with water incorporated into its crystal structure.
- Example: Feldspar weathering to form clay.
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Oxidation: Loss of electrons from a compound or element during a chemical reaction, often when the mineral reacts with oxygen.
- Example: Iron oxides forming when iron-containing minerals react with oxygen.
- Example: Sulfur reacting to form sulfuric acid.
Additional Concepts
- Spheroidal weathering: Mechanical and chemical weathering processes round boulders and other rocks.
- Salt cracking: Growth of dissolved salt crystals widens cracks and fractures rocks.
- Exfoliation: Large plates or shells of rock split away like the layers of an onion (a mechanical process often followed by chemical weathering).
- Acid rain: Sulfur dioxide reacts with water to create sulfuric acid, damaging structures and causing weathering.
- Water carries away dissolved ions, creating caves.
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Description
Test your understanding of geological processes including epigene and hypogene mechanisms. This quiz covers topics such as weathering, erosion, transportation, and deposition of rocks. Great for students enrolled in Physical Geology course.
