Podcast
Questions and Answers
What are sedimentary rocks?
What are sedimentary rocks?
Rocks formed through the accumulation and lithification of sediments.
How are sedimentary rocks formed?
How are sedimentary rocks formed?
Physical weathering involves processes such as ________ and root wedging.
Physical weathering involves processes such as ________ and root wedging.
frost wedging
Match the types of sedimentary rocks with their examples:
Match the types of sedimentary rocks with their examples:
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Differential weathering is based on shape and rock type.
Differential weathering is based on shape and rock type.
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Ripple marks develop parallel to flow in sandy sediments.
Ripple marks develop parallel to flow in sandy sediments.
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What is diagenesis in sedimentary rocks?
What is diagenesis in sedimentary rocks?
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Which of the following is NOT a type of weathering?
Which of the following is NOT a type of weathering?
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What are sedimentary structures?
What are sedimentary structures?
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What is an example of a biochemical sedimentary rock?
What is an example of a biochemical sedimentary rock?
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Mud cracks indicate alternate wet and ________ conditions.
Mud cracks indicate alternate wet and ________ conditions.
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Study Notes
Diagenesis
- Diagenesis is the sum of all physical, chemical, and biological changes that occur after sediment is deposited.
- Pressure and temperature increase as sediment is buried.
- Lithification, dissolution, recrystallisation, hydration, and bacterial action are all part of diagenesis.
Sedimentary Structures
- Features formed during sediment deposition.
- Offer insight into depositional environments.
Bedding and Stratification
- Common in sedimentary rocks.
- Appear as planar, horizontal beds.
- Bedding planes are the boundaries between two beds.
- Reflect changing conditions during deposition, such as changes in the transporting medium or sediment source.
Formation of Bedding
- Changes in sediment composition, grain size, sorting, etc. result from changing conditions.
Stratigraphic Formations
- Unique rock units that can be identified and mapped over large areas.
- Formations are named after locations where they are best exposed.
Ripple Marks and Dunes
- Water flowing over loose sediment creates bedforms, which reflect flow velocity and grain size.
- Ripple marks are cm-scale ridges and troughs perpendicular to flow in sandy sediments.
- Dunes are larger-scale versions of ripple marks, ranging from 50 cm to over 100 m.
Cross Bedding
- Sand moves up the gentle side of a ripple or dune and piles up at the crest.
- Sand then slips down the steep face, moving down-current and being buried by the next avalanche of sand.
- The slip faces are preserved as cross beds.
Turbidity Currents and Graded Beds
- Turbidity currents form in deep basins that receive periodic pulses of turbid water.
- As the pulse wanes, water loses velocity and grains settle.
- Coarser material settles first, followed by medium and then fine grains.
- This process forms graded beds (coarse to fine upward).
Mud Cracks and Scour Marks
- Mud cracks indicate alternating wet and dry terrestrial conditions.
- Scours form when debris is dragged along the bottom of a river.
- The scour is filled in with sediment and can make casts.
Depositional Environments
- Locations where sediment accumulates.
- Vary in energy regime, sediment transport, depositional processes, and chemical, physical, and biological characteristics.
Glacial Environments
- Sediments are created, transported, and deposited by the actions of moving glacial ice.
- Ice carries and dumps every grain size.
- Glacial till, a poorly sorted mixture of sediment, is a common feature.
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Description
Explore the fascinating processes of diagenesis and sedimentary structures in this quiz. Learn about the changes that sediments undergo after deposition, including lithification and stratification. Test your knowledge on bedding, stratigraphic formations, and the features that reveal depositional environments.
