Chapter 14 Flashcards
What is weathering?
the process of breaking down rock and minerals. Weathering is caused by Sun’s energy, wind, running water, ice, chemical reactions, and the actions of organisms.
What is the difference between young mountains and old mountains?
Young= sharp peaks, no vegetation at the peaks. Old= round peaks, not that tall, and there is vegetation.
What is mechanical weathering?
the process of breaking down rocks and minerals into smaller pieces by physical force. Also called physical weathering.
What is chemical weathering?
the process of breaking down rocks and minerals by chemical reactions.
What two main sources of energy cause weathering?
the Sun and Earth’s internal energy.
What is the difference between the Sun and Earth’s internal energy?
The Sun= drives our weather and the water cycle.
Earth’s internal energy= results in the movement of lithospheric plates on Earth’s surface.
How is gravity important in weathering?
important process because gravity causes water and pieces of rock to move downhill.
What is frost wedging?
mechanical weathering that results from freezing water.
Where does frost wedging occur?
occurs in areas with available water and temperatures that fluctuate around the freezing point.
What is biological weathering?
Weathering by plants and animals.
When does mechanical weathering happen?
weathering by plants occurs when roots grow into cracks in a rock.
What is root wedging?
roots exert force on the rock as they grow and may cause the rock to split.
How do animals cause weathering?
Animals cause mechanical weathering when they dig into soil or burrow underground.
What is exfoliation?
Exfoliation is a weathering process that results in rock layers peeling away. Outer layers peel away first, and then the layers underneath expand and get weathered themselves.
How does wind cause weathering?
Sand gets blown around in the wind and chips away tiny bits of rock from the surface of exposed rock.
What is a hoodoo?
A hoodoo is a tall pillar that forms when wind weathers down large rocks. (See page 329 for a picture in the bottom right corner of the page)
What causes chemical weathering? (4 things)
- water and minerals
- acid rain
- oxygen in the atmosphere
- weathering by plants
How can water and minerals cause chemical weathering?
water can react with minerals in the rock and cause chemical changes. (example: feldspar reacts with water to make clay)
How does acid rain cause chemical weathering?
Acid rain happens when pollutants in the atmosphere mix with water and form an acidic solution. That acidic solution comes down as rain and weathers rock.
How does oxygen in the atmosphere cause chemical weathering?
Oxygen in the atmosphere changes metals in minerals through a process called oxidation. Example: oxygen combines with iron to make rust.
How can plants cause chemical weathering?
Moss and other plants can cause chemical weathering because they release chemicals that cause the rock to break down.
Can chemical and mechanical weathering happen at the same time or do they have to happen separately?
They can happen at the same time.
What factors affect the rate of weathering? Give reasons/examples
1) weather and climate. Ex: rocks weather faster in warm, humid climates. The weather slower in dry, cold climates.
2) Plants and enimals. Ex: plants growing or animals digging can change how much of a rock is exposed to weathering
3) minerals. The kind of minerals on a rock changes how fast the rock weathers. Ex: marble weathers faster than grainte.
4) Surface area. More exposed surface area –> weathers faster.
What is erosion?
the process of moving sediment by wind, water, ice, or gravity
What moves sediment?
running water, wind, ice
How does sediment usually move?
downhill because of gravity
How does running water move sediment?
when water/wind/ice moves sediment, “depositing” it (i.e. putting it somewhere) is called deposition
What affects how water moves sediment?
- volume of water (lots of water moves sediment really easily; a little water moves just a bit)
- slope (steep slopes –> lots of erosion compared to shallow slopes.) p. 334 for picture
- rockiness: rocky landscapes can trap sediment, so less erosion happens
What sorts sediment? How?
Water sorts sediment.
When running water slows down (example: River flowing into the sea), the largest particles being carried settle to the bottom first. Then the middle particles settle. Finally, the smallest particles settle. (see page 335 for picture)
We call this a graded bedding. The sediment is ordered with the largest particles on the bottom, then medium, and finally smallest on top.
What is the direction of younging?
the direction of the younger layers of sediment. remember: youngest/finest particles are on top, oldest/largest particles are on bottom.
How does ice move sediment?
Glaciers can slide around without breaking; as they slide around in a mountain valley (see page 337 for picture), they drag rock/sediment with them.
How does gravity move sediment
define mass wasting, landslide, rockfall, mudflow
- -Mass wasting - the downhill movement of large amounts of rock and sediment because of gravity.
- -Landslides - when large mass of soil or rock slides down a steep slope
- -Rockfall - a big chunk of rock is split off of a large landform due to weathering
- -mudflow - an event that occurs when a large amount of rock and water flow down a mountain
What is slumping?
when soil particles become surrounded by water so that the ground slides or slumps. See 340 for pictures.
How do people cause erosion?
–when humans use the land and build on it, they can cause erosion: farmers removed topsoil and grass, so the earth got very dusty.
How do rivers shape land?
- they form river valleys
- river valleys tend to be v-shaped
What is a floodplain?
a flat land alongside a river that tends to get flooded.
What is a meander?
an s-shaped curve that forms in some rivers: picture on page 344
