Questions and Answers
What layer of the Earth comprises 82% of its volume and is primarily made of silicate rocks rich in magnesium and iron?
Which type of crust is composed mainly of basalt and accounts for 71% of the Earth's crust?
What is the primary composition of the inner core of the Earth?
How thick is the oceanic crust compared to the continental crust?
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What process involves the transfer of heat through the collision of atoms primarily in solids?
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Which layer of the Earth is considered the hottest, with temperatures reaching up to 7000°C?
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What defines the compositional layers of the Earth?
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Which of the following statements is true about the continental crust?
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How does the concentration of specific minerals in magma affect crystal growth?
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What happens to crystal grains of soluble contents during crystallization?
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What effect do abrupt changes in physico-chemical conditions have on crystals?
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Which type of magma contains 65-75% SiO2 and is characterized by low calcium, magnesium, and iron?
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How are igneous rocks classified based on the composition of magma?
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What characterizes acidic igneous rocks?
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What is the typical temperature range for andesitic magma?
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Which type of magma is characterized by high viscosity and significant gas content?
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What is the primary characteristic of basic rocks?
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How are volcanic rocks primarily formed?
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Which of the following is a characteristic of plutonic rocks?
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What defines hypabyssal rocks?
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What does texture in igneous rocks refer to?
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Which type of texture is characterized by crystals that are broadly equal in size?
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What type of texture is described as being microgranular with perfect outlines?
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What factor does NOT affect the texture of igneous rocks?
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What natural structure is formed by the drifting apart of the Arabian, Indian, and African plates?
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Which of the following islands is an example of an island arc formed by the North American and Pacific plates?
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What process is indicated when rocks or soil lose strength due to weathering?
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Which type of weathering involves the physical breakdown of rocks into smaller pieces without changing their chemical composition?
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What should be avoided when selecting sites for construction?
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What kind of fault caused the 2008 Wells earthquake in Nevada?
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Which of the following phenomena occurs due to the movement of the earth's crust?
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Which type of weathering includes the formation of rounded boulders from angular rocks?
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What is a critical consideration for construction engineers regarding potential sites?
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Which of the following is an example of an earthquake fault that caused a significant historical earthquake?
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What is a rock that is at the boundary between igneous and metamorphic rocks called?
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What does metasomatism involve?
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Which of the following is NOT a form of metamorphism?
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What is the primary result of metamorphism?
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Which metamorphic process involves the creation of new minerals with different crystal structures?
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What occurs during neocrystallization in the metamorphic process?
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What is one characteristic of metamorphic rocks?
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Which process in metamorphism requires small amounts of water to facilitate mineral grain dissolution?
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Study Notes
Geohydrology/Hydrogeology
- Focuses on groundwater movement throughout the environment.
Structure of the Earth
- Earth is composed of various spherical layers categorized by chemical composition and mechanical properties.
Compositional (Chemical) Layers of Earth
- Layers defined by their chemical elements.
Crust
- Composed of various elements, thickness varies: 3-5 miles under oceans, ~25 miles under continents.
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Types of Crust:
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Oceanic Crust (Basaltic):
- Makes up 71% of the crust, consists of basalt and gabbro from volcanic activity.
- Heaviest sedimentation near shores.
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Continental Crust (Granitic):
- Accounts for 29%, features a variety of rocks primarily granite, which is less dense than oceanic crust and generally thicker.
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Oceanic Crust (Basaltic):
Mantle
- Comprises 82% of Earth’s volume, approximately 1,800 miles deep.
- Dominated by magnesium and iron-rich silicate rocks, with convection currents driven by heat.
Core
- Center made primarily of 85% iron and 15% nickel.
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Inner Core:
- Solid, around 760 miles in radius, temperatures can reach up to 7,000°C.
Geological Features
- Great Rift Valley: Formed by the drifting apart of the Arabian, Indian, and African plates.
- Aleutian Islands: Arc formed due to the subduction of the North American plate under the Pacific plate.
- Ryukyu Islands: Formed by fluctuations in the Earth’s crust.
Weathering Processes
- Erosion: Removal of surface material.
- Transportation: Movement of sediments.
- Deposition: Accumulation of sediments which can form features like sand dunes.
- Weathering can be chemical, physical, or exfoliation.
Engineering Implications of Weathering
- Selecting quarries for construction materials requires assessing the impact of weathering on rock strength.
- Sites near moving dunes are challenging due to potential damage; special measures must be employed if selected.
Types of Geological Formations
- Earthquakes are caused by faults, such as the Sierra Nevada fault which triggered a significant earthquake in 1872.
Magma Characteristics
- Chemical composition affects magma type:
- Basaltic: Low silica, high temperature.
- Andesitic: Intermediate silica and properties.
- Rhyolitic: High silica content with low gas levels.
Classification of Igneous Rocks
- Based on silica content and solidification process.
- Acidic Rocks: High silica (over 66%), light in color.
- Basic Rocks: Low silica (under 50%), darker and denser in color.
- Volcanic rocks: Form from lava cooling on the surface.
- Plutonic rocks: Form beneath Earth's surface, coarse-grained due to slow cooling.
Texture of Igneous Rocks
- Determined by size, shape, and arrangement of minerals.
- Equigranular Texture: Minerals are roughly the same size, commonly found in granites.
Metamorphism Processes
- Metamorphic rocks are formed under high heat, pressure, and mineral-rich fluids without melting.
- Key processes:
- Recrystallization: Change in mineral size and shape.
- Phase Change: New minerals formed with the same chemical formula but different structures.
- Neocrystallization: Formation of new minerals as original minerals become unstable.
- Pressure Solution: Partial dissolution of mineral grains requiring water.
- Plastic Deformation: Softening and deformation of minerals under pressure.
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Description
Explore the intricate movements of groundwater and the layered composition of Earth in this quiz. Delve into the characteristics of the crust, mantle, and core, and understand the differences between oceanic and continental crusts. Test your knowledge of geohydrology and the Earth's chemical layers.
