Sedimentary rocks, weathering, erosion, soil study Flashcards
Are sediments rocks?
No
What creates sedimentary rocks?
sediments are compacted and then cemented together
What creates sediments?
Weathering, moved by erosion, and dropped by deposition
Clastic
Made of sediments of pre-existing rocks
What are the types of Non-Clastic (Sedimentary) rocks?
Chemical, and Biological
Chemical
Non-Clastic rock
Made of dissolved sediments that precipitate out of water
Biological (Organic)
Non-Clastic rock
Rock forms from biological (living) sources
What are the unique features of sedimentary rocks
Strata, Fossils, Ripple Marks, and Mud Cracks
Strata
If undisturbed sedimentary rock is put down in layers
Fossils
Remains or traces of ancient life
Ripple Marks
Tells you that the rock was formed where there was moving water
Mud cracks
Tells you that the rock was formed as sediments were drying out
Weathering
The breaking of rock into smaller pieces (sediments)
Erosion
Movement of sediments
Deposition
The dropping of sediments.
Mechanical Weathering
Also called physical weathering
Breaking down of rock into smaller pieces without
changing the chemistry of the rock
Chemical Weathering
Chemical reactions cause rock to break down, the chemistry of the rock has changed
What happends the more physical weathering a rock experiences
The smoother the surface
Wind
Mechanical (Physical) Weathering
sand dunes
Water
Mechanical (Physical) Weathering
waves and rivers
Exfoliation
Mechanical (Physical) Weathering
glaciers
Plant Action
Mechanical (Physical) Weathering
like frost wedging but with plant roots
Ice
Mechanical (Physical) Weathering
frost wedging is when water gets into crevices and expands
Plant Action
Mechanical (Physical) Weathering
like frost wedging but with plant roots
Pressure Unloading
When a top layer of rock is scraped off it relieves pressure and rock underneath expands
Oxidation
Chemical Weathering
rusting of iron
Acid Rain
Chemical Weathering
rain that has been made acidic by certain pollutants in the air
Carbonation
Chemical Weathering
aves and caverns
Lichens
Chemical Weathering
can grow on rocks and release enzymes to break them down
Deposition
When the force that causes erosion stops or eases
large/dense sediments are dropped first
Sorting is a common natural occurrence
Small sediments can stay suspended
Rivers
weathering breaks down rocks and soil, erosion transports the broken material, and deposition is when the transported material settles out and is dropped in a new location
River Deposits
Flood Plain - Areas on banks of rivers that get flooded.
Delta - Fan/triangle shaped deposit at mouth of river.
Alluvial Fan - Fan shaped deposit at base of mountain.
Glaciers
As a glacier moves the surface is scratched and rocks can be moved large distances
Ocean Waves
weathering (breaking down rocks), erosion (moving broken materials), and deposition (dropping materials)
Mass Movement
Gravity causes this
EX: Landslides/Mudslides, avalanches, creep
Succession
Created over time as solid bedrock is exsposed to weathering forces
Soil
Product of weathering, erosion, and deposition
Wind
causes weathering & erosion
Soil Horizons (layers):
Horizon O- organic matter/humus
Horizon A- topsoil, rich dark and at surface
Horizon B- subsoil, clay that fell from above layer
Horizon C- partially weathered bedrock
Horizon D- solid bedrock, parent material
Agriculture and Overgrazing
Farming removes plants that are native and replaces them with shallow rooted plants that are
usually tilled every year
Construction
Pulls up all plants that held the soil in the ground
Windbreaks
Surrounding fields with trees to reduce wind erosion and weathering
Logging and Mining
Logging and Mining
Contour Farming
Plowing along the lines of the land
Strip Farming
Alternation rows of crops
No Till Farming
The field isn’t disturbed between harvest and planting
What process creates sediments from rocks?
Weathering
Weathering involves breaking down rocks into smaller pieces.
What is the movement of sediments called?
Erosion
Erosion refers to the transport of weathered materials.
What is the term for the dropping of sediments?
Deposition
Deposition occurs when the energy causing erosion decreases.
What defines clastic sedimentary rocks?
Rocks made of sediments of pre-existing rocks
Clastic rocks can be classified by sediment size.
What are non-clastic sedimentary rocks?
Rocks formed from dissolved sediments that precipitate out of water
Includes chemical and biological (organic) rocks.
Give examples of biological sedimentary rocks.
- Coal
- Coquina
Coal is formed from swamp plants, while coquina is made from shells.
What is strata in sedimentary rocks?
Layers of undisturbed sedimentary rock
Strata indicate the order of sediment deposition.
What do fossils in sedimentary rocks indicate?
Remains or traces of ancient life
Fossils provide evidence of past life forms.
What do ripple marks in sedimentary rocks signify?
Formation in moving water
Ripple marks indicate the environment of deposition.
What indicates that a rock was formed as sediments dried out?
Mud cracks
Mud cracks form when wet sediments lose moisture.
What is mechanical weathering?
Breaking down of rock into smaller pieces without changing its chemistry
Also known as physical weathering.
What is chemical weathering?
Chemical reactions cause rock to break down, changing its chemistry
Examples include oxidation and acid rain.
List examples of mechanical weathering.
- Wind
- Water
- Exfoliation
- Ice
- Plant Action
- Pressure Unloading
Each process contributes to the physical breakdown of rocks.
What are common causes of chemical weathering?
- Oxidation
- Acid Rain
- Carbonation
- Lichens
These processes alter the chemical structure of rocks.
What is the sorting process in deposition?
Larger/dense sediments are dropped first, smaller ones stay suspended
Sorting occurs when the energy of the transporting medium decreases.
What is a flood plain?
Areas on banks of rivers that get flooded
Flood plains are formed by river deposition.
What is a delta?
Fan/triangle shaped deposit at the mouth of a river
Deltas are formed from sediments deposited by river flow.
What is an alluvial fan?
Fan shaped deposit at the base of a mountain
Alluvial fans form when a river slows down upon exiting a mountain.
What impact do glaciers have on the landscape?
Scratching the surface and moving rocks over large distances
Glacial movement shapes terrain through erosion.
How do ocean waves cause weathering?
By hitting the land and causing erosion and deposition
Wave energy influences the shape of coastlines.
What is mass movement?
Movement of soil and rock due to gravity
Includes landslides, mudslides, and creep.
What are the components of soil?
- Sediments
- Organic material (humus)
- Water
- Air
Soil is formed from weathering and deposition processes.
What are the soil horizons?
- Horizon O: organic matter/humus
- Horizon A: topsoil
- Horizon B: subsoil
- Horizon C: partially weathered bedrock
- Horizon D: solid bedrock
Horizons represent different layers of soil development.
What factors determine soil type?
- Parent material
- Time
- Climate
- Organisms
- Slope
Different environments produce various soil types.
What type of soil consists of 10% clay, 60% silt, and 30% sand?
Silt Loam
Soil texture can be represented in a texture pyramid.
What are causes of soil erosion?
- Agriculture
- Overgrazing
- Construction
- Logging and Mining
These activities lead to soil degradation.
List solutions to soil erosion.
- Windbreaks
- Contour Farming
- Strip Farming
- No Till Farming
These practices help preserve soil structure and reduce erosion.
