Geology Lecture 3: The Rock Cycle

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Questions and Answers

Which of the following is NOT a characteristic of minerals?

Inorganic

Naturally occurring

Can be man-made (correct)

Solid

What is the difference between a mineral and a rock?

Minerals are solid, while rocks can be solid or liquid.

Minerals are formed through natural processes, while rocks are man-made.

Minerals are inorganic, while rocks are organic.

Rocks are made of minerals, while minerals are the building blocks of rocks. (correct)

What is an outcrop or exposure?

The process of rocks changing form over time

An exposed rock surface (correct)

A layer of rock that is buried deep underground

A type of rock found in specific locations

Why are rock-forming minerals essential for identifying and classifying rocks?

They contribute to the unique characteristics of each rock type. (C) Signup and view all the answers

What is the meaning of the term 'crystalline solid' when applied to minerals?

A mineral that has a repeating internal structure. (C) Signup and view all the answers

Which of the following is an example of an outcrop?

A cliff face along a coastline (C) Signup and view all the answers

What is the significance of the rock cycle in understanding Earth's geology?

It shows how rocks are constantly being transformed through various processes. (C) Signup and view all the answers

What type of rock is composed of minerals that have been cemented together?

Sedimentary (B) Signup and view all the answers

What is the main component of animal shells and skeletons?

Calcite (D) Signup and view all the answers

Which type of igneous rock is formed by rapid cooling?

Aphanitic (C) Signup and view all the answers

What are the two stages of cooling in a porphyritic rock?

Rapid cooling followed by slow cooling (C) Signup and view all the answers

Which of the following factors contribute to the formation of sedimentary rocks?

Weathering, erosion, and compaction (D) Signup and view all the answers

What is the smallest sediment particle size mentioned in the content?

Clay (B) Signup and view all the answers

Which type of igneous rock is characterized by large, visible crystals?

Phaneritic (C) Signup and view all the answers

Which of the following minerals is not a silicate mineral?

Calcite (C) Signup and view all the answers

Which of the following is not a process involved in the formation of sedimentary rocks?

Metamorphism (C) Signup and view all the answers

What is the main component of the Earth's crust?

Silicate minerals (D) Signup and view all the answers

Which of the following is a characteristic of igneous rocks formed by rapid cooling?

Fine-grained texture (C) Signup and view all the answers

Study Notes

Lecture 3: The Rock Cycle

The rock cycle is a continuous process where rocks are transformed from one type to another through various geological processes.
Rocks are formed from minerals, which are naturally occurring, inorganic, crystalline solids with a specific chemical composition.
Rocks are aggregates of one or more minerals.
Rocks are coherent, in contrast to a handful of sand.

Mineral Properties

Minerals are naturally occurring, inorganic, crystalline solids with a specific chemical composition.
Minerals have a repeating crystalline structure.

Rock Types

Igneous rocks: Formed from the cooling and solidification of magma or lava.
- Extrusive igneous rocks (volcanic): Cool quickly on the Earth's surface, forming fine-grained textures.
  - Examples: Rhyolite, Andesite, Basalt.
- Intrusive igneous rocks (plutonic): Cool slowly beneath the Earth's surface, forming coarse-grained textures.
  - Examples: Granite, Diorite, Gabbro.
- Classification is based on the minerals present and the texture.
Sedimentary rocks: Formed from the accumulation and cementation of sediments. Sediments are weathered and eroded from pre-existing rocks or precipitates. They undergo lithification.
- Types: Detrital (fragments from pre-existing rocks) and chemical/biochemical (minerals extracted from solutions or produced by organisms).
  - Examples: Sandstone, conglomerate, limestone.
Metamorphic rocks: Formed from the transformation of existing rocks by heat, pressure, or chemical reactions. They do not melt completely.
- Types: Foliated (due to pressure creating layers) and nonfoliated (doesn't have layers).
  - Examples: Slate, schist, gneiss, marble, quartzite.
- Classification based on the composition and texture (foliated/nonfoliated).

Sedimentary Rock Formation: Lithification

Sediments accumulate
Sediments are compacted by weight of overlying material.
Sediments are cemented by minerals.
Sediment particle sizes: Gravel, sand, silt, and clay

Rock Cycle Processes

Weathering and erosion: Breaks down rocks into smaller pieces.
Transportation: Moves sediments.
Deposition: Accumulates sediments.
Lithification: Compacts and cements sediments to form sedimentary rocks.
Metamorphism: Alters rocks by heat, pressure, or chemical reactions.
Melting: Creates magma, which can cool and solidify to form igneous rocks.
Uplift and exposure: Brings rocks to the surface.

Igneous Rock Classification

Aphanitic: Rapid cooling, small crystals.
Phaneritic: Slow cooling, large crystals.

Metamorphic Rock Formation

Igneous or sedimentary rocks are changed by heat and pressure
Types of changes:
- Compositional (new minerals form).
- Textural (minerals align) - Foliated textures.
Depending on the degree of metamorphism, or the original rock type, different types of metamorphic rocks result.

Foliated vs. Non-foliated Textures

Foliated: layers in the rock result from pressure.
- Examples: Slate, schist, gneiss
Non-foliated: Rocks that cooled/were formed without layers
- Examples: Marble, quartzite

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Description

Explore the fascinating process of the rock cycle in this quiz. Understand the formation and classification of different rock types, including igneous rocks. Learn about minerals and their properties as key components in rock formation.