Chapter 6- The Rock Cycle (Week 2/3) Flashcards
What is a rock, and what does it consist of?
A rock is a solid mass of geological materials, which can include individual mineral crystals, inorganic non-mineral solids like glass, fragments broken from other rocks, and even fossils. The geological materials in rocks may be inorganic, but they can also include organic materials such as partially decomposed plant matter preserved in coal.
Can a rock be composed of only one type of geological material or mineral?
Yes, a rock can be composed of only one type of geological material or mineral, but many rocks are composed of several types.
What are examples of geological materials that can be found in rocks?
Geological materials in rocks can include individual mineral crystals, inorganic non-mineral solids like glass, pieces broken from other rocks, and even fossils. Organic materials, such as partially decomposed plant matter preserved in coal, can also be part of rocks.
Can you describe the composition of the rock shown in Figure 6.1?
Figure 6.1 shows a rock made of three different kinds of minerals, illustrating that rocks can be composed of multiple types of geological materials.
What are the three main categories of rocks, and how do they form?
Igneous rocks form when melted rock cools and solidifies.
Sedimentary rocks form when fragments of other rocks are buried, compressed, and cemented together. They can also form when minerals precipitate from solution, either directly or with the help of an organism.
Metamorphic rocks form when heat and pressure alter a pre-existing rock. Metamorphism does not involve melting of the rock, even though temperatures can be very high.
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What is the rock cycle, and what forces drive it?
The rock cycle is a continuous process where rocks on the Earth’s crust are constantly changing from one form to another.
It is driven by two main forces:
1. Earth’s internal heat: This heat causes material to move around in the core and mantle, driving plate tectonics.
2. Hydrological cycle: This involves the movement of water, ice, and air at the surface and is powered by the sun.
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Why is the rock cycle still active on Earth?
The rock cycle remains active on Earth because its core is hot enough to keep the mantle moving, the atmosphere is relatively thick, and there is liquid water. Other planets or their satellites, where these conditions are not met (e.g., Mercury), may have a virtually dead rock cycle.
Describe the starting point of the rock cycle.
The rock cycle often begins with magma, which is melted rock located within the Earth. If magma cools slowly within the Earth, intrusive igneous rocks are formed. If magma erupts onto the surface, it is called lava, and when lava cools rapidly on the Earth’s surface, it forms extrusive igneous rocks.
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How does mountain building contribute to the rock cycle, and what processes are involved in the weathering of rocks?
Mountain building: It lifts rocks upward, exposing them to the surface.
Weathering: This includes chemical processes that break rocks apart and physical processes. For instance, water getting into cracks, freezing, and forcing the cracks wider is an example of physical weathering
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What role does uplift through mountain building play in the rock cycle?
Uplift through mountain building is a process that brings rocks, once buried deep within Earth, to the surface. This exposure at the Earth’s surface is essential for the ongoing rock cycle.
What happens to the products of weathering, and how are they transported and deposited?
Weathering Products: Mainly small rock and mineral fragments.
Erosion: The products are eroded.
Transportation: Erosion products are transported by various agents, including glaciers, streams, waves, wind, etc.
Deposition: The transported sediments are deposited in new locations.
Can you give an example of transportation of sediments?
Yes, for instance, the transportation of fine-grained sediment particles by wind during the Great Depression in the 1930s.
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What happens to sediments after deposition, and how do sedimentary rocks form?
Depositional Settings: Sediments are deposited in various environments, including stream channels, lakes, deserts, and the ocean.
Sedimentary Structures: Different depositional settings lead to specific sedimentary structures, such as ripples formed by flowing water.
Burial and Compression: If not re-eroded, sediments get buried by additional layers. At greater depths, compression occurs, forcing particles closer together.
Cementation: Mineral crystals grow around and between particles, cementing them together.
Result: The cemented and compressed sediments become sedimentary rock.
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Can you provide an example of sedimentary structures?
Certainly, for instance, depicts ripples formed by flowing water moving sand along the bottom of the South Saskatchewan River.
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How do rocks transform into metamorphic rocks, and what conditions contribute to this process?
Formation Conditions: Rocks buried deeply in the crust experience high pressures and temperatures.
Metamorphic Transformation: Existing rocks, subjected to extreme conditions, undergo metamorphic transformation.
Mechanisms:
-Physical Changes: Minerals may re-form into larger crystals of the same mineral.
-Chemical Changes: Minerals within the rock react to form new minerals.
Result: The transformed rocks become metamorphic rocks.
