Sedimentary Rocks Formation Flashcards

Questions and Answers

What is sediment and how does it form?

Unconsolidated particles created by the weathering and erosion of rock, by chemical precipitation from solution in water, or from the secretions of organisms.

What are clasts?

Chunks of rock.

How does sediment form?

Weathering, gravity and erosional agents remove products of weathering and bring them to a new location where they are deposited.

What are the 5 steps that turn existing rocks into a new sedimentary rock?

<ol> <li>Weathering (sediment) 2. Erosion (sediment) 3. Transport 4. Deposition 5. Lithification</li> </ol> Signup and view all the answers

What are the 4 classes of sedimentary rocks?

Detrital (clastic), Biochemical, Organic, Chemical. Signup and view all the answers

What are the differences between a conglomerate, sandstone, siltstone, and shale?

They are all detrital rocks but differ in particle size. Signup and view all the answers

What are chemical sedimentary rocks composed of?

Derived from material (ions) that is carried in solution to lakes and seas then precipitates. Signup and view all the answers

Can you think of an example of chemical sedimentary rocks?

Salt left behind as a body of saltwater evaporates. Signup and view all the answers

How does coal form?

Coal is formed from the burial of large amounts of plant material over extended periods under increased temperature and pressure. Signup and view all the answers

How do evaporites or inorganic crystalline limestone form?

Inorganic limestone forms when chemical changes or high water temperatures increase the concentration of calcium carbonate to the point that it precipitates. Signup and view all the answers

What does the term 'depositional environment' mean?

Describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment. Signup and view all the answers

What are strata?

Parallel layers of sedimentary rock. Signup and view all the answers

What is a bedding plane?

Flat surfaces along which rocks tend to separate or break. Signup and view all the answers

What is a rock formation?

A rock unit that is distinctive enough in appearance that it can be differentiated from surrounding rock layers. Signup and view all the answers

Study Notes

Formation of Sedimentary Rocks

Sediment consists of unconsolidated particles produced by weathering, erosion, chemical precipitation, or biological activity, transported by water, wind, or glaciers.
Clasts are chunks of rock formed from broken-down larger rock materials.
The sediment formation process involves weathering, erosion, transport, deposition, and lithification.

Steps to Form Sedimentary Rocks

Weathering breaks down rocks into sediment.
Erosion moves sediments to new locations using gravity and natural agents like water and wind.
Transport refers to the movement of sediments to areas of deposition.
Deposition occurs when sediments settle in new locations.
Lithification transforms deposited sediments into solid rock through compaction and cementation.

Classes of Sedimentary Rocks

Detrital (clastic): Form from solid weathering products, mainly consisting of clay minerals and quartz; classified by particle size.
Chemical: Composed of minerals precipitated from water solution due to chemical processes; derived from dissolved ions.
Biochemical: Formed indirectly through biological processes of organisms, leading to precipitation of sediments in aquatic environments.
Organic: Composed of the soft tissues of living organisms, such as coal.

Types of Detrital Rocks

Conglomerate: Contains rounded sediments with predominant gravel-size particles.
Sandstone: Composed mostly of sand-sized grains.
Shale: Most common sedimentary rock; consists of very fine-grained sediment mainly made of clay minerals.
Siltstone: A fine-grained rock with clay-sized grains mixed with slightly larger silt-sized particles.

Chemical Sedimentary Rocks

Composed of precipitated minerals derived from dissolved ions in water bodies.
Example: Salt deposits form when saltwater evaporates.

Organic Sedimentary Rocks

Coal is formed from buried plant material over time in swampy conditions, undergoing changes from pressure and temperature where impurities are removed.

Inorganic Sedimentary Rocks

Inorganic crystalline limestone forms through chemical changes that increase the concentration of calcium carbonate, leading to precipitation.

Sediment Structure and Environments

Strata are parallel layers of sedimentary rock.
Bedding planes are flat surfaces that separate different layers and indicate changes in sedimentation episodes.
Ripple marks suggest environments such as beaches or stream channels.
Cross beds form under inclined layers created by water or wind currents.

Depositional Environment

Refers to the combination of physical, chemical, and biological processes specific to the deposition of certain types of sediment.
Different sedimentary environments exist on land, including glaciers and mountain streams.

Description

Explore the essential concepts of sedimentary rock formation through flashcards. Learn about sediment types, their origins, and the role of clasts in geology. Perfect for students looking to deepen their understanding of sedimentary processes.