Chapter 10 & 12 Weathering & Erosion
SCIENCE Weathering & Erosion
Terms in this set (44)
the loose material
at the surface of the earth
decayed organic material in soil
small particles produced by the weathering of rocks
contains minerals from weathered rocks & humus;
most plants germinate & grow roots in this layer
the process of breaking down rock into smaller and smaller pieces - temp, water, wind, & plant and animal life all contribute to this process
process of rocks transformed into NEW substances - affected by temp, moisture, wind, weather, acids, & living organisms
rainwater mixed with gasses from burning fossil fuels that is harmful to trees and wildlife
mechanical weathering process water freezes & expands in cracks of rocks, forces rocks apart like a wedge. Water runs into tiny cracks during warm weather. When it gets cold, the water freezes. It expands, the crack widens. The crack holds more water when it freezes again. Expands and rock breaks over time.
a type of mechanical weathering that occurs when rocks rub against each other - caused by wind or water. (examples - rocks tumbling against one another in a fast moving river; rocks falling down a mountain, rocks shaped by sand blown against them by the wind)
Sturdy small plants that grow like a crust on rocks or tree trunks
when metal is exposed to water and oxygen and rust forms - (example - iron, cars)
What type of chemical weathering creates caves or caverns?
Acids in groundwater.
dropping of sediment and rocks in a new location
weathered material moving from one place to another
Example of frost action
How do lichens break down rock?
Lichens are living things and they have weak acids that chemically weather rocks.
Soft rock wears away, leaving behind harder rock
Why do small rocks weather faster than large rocks?
When a large rock is broken into smaller blocks, the total volume of the rocks is the same. There is now more surface area though. Weathering happens over a greater surface area. The smaller rock weathers faster than if it was one large chunk.
What type of climate does chemical weathering happen faster?
Humid and warm
What is leaching?
Excess rain carries the nutrients out of the topsoil away from the roots of the plant.
Which climate zone has the most productive soil for growing crops?
Temperate forests and grasslands
What is it called when you plow across the slope of a hill?
Contour plowing - prevents erosion
Cutting narrow, flat platforms in steep slopes to prevent erosion.
leaving dead plant stalks on the ground to provide cover to the soil - prevents erosion
What type of climate causes mechanical weathering to happen at a greater rate?
cold and wet
the soil supports plan growth
What is the soil like in temperate forests and grasslands
thick and fertile
What helps stop or slow down wind erosion?
increased plant cover
Describe desert pavement
pebbles and small broken rocks that are left behind after deflation (wind erosion process that carries away all fine sediments and leaves behind the heavier rocks)
How do sand dunes move?
Winds carry sand from one place to another. Sand hits an obstacle and slows down. Moving the small amounts of sand eventually moves the entire dune.
What type of glacier is found in mountainous areas?
What type of glacier covers large areas of land and affects the largest area?
The skipping and bouncing movement of sand particles in the direction the wind is blowing. The moving particles strike other sand grains, and cause them to roll and bounce forward.
What type of glacier could smooth the landscape or flatten mountains?
What do waves make when they break rock into small pieces?
What is the force that moves glaciers?
Movement of large amounts of soil, rock, and other materials due to gravity.
Extremely slow form of mass movement.
Which type of mass movement is rock fall?
Rapid mass movement
Three ways weak acids cause chemical weathering of rocks.
1) Acid precipitation - Rain falls to the ground, chemical reaction with rocks occurs more rapidly. Acid precipitation occurs because of fossil fuels, factory emissions, and volcano eruptions.
2) Acid in groundwater - Weak acids react with rock which passes through groundwater. Over time, chemical reactions weather the rock and cause caves, caverns and sinkholes to form.
3) Living things like lichens - The acids break down rocks chemically by dissolving minerals in the rock.
How does elevation affect the rate which rock weathers?
Rocks at higher elevations weather more quickly than those at lower elevations. They are more exposed to wind, rain, and cold temperatures. Rocks that are higher are also more effected by gravity. The rocks fall away from the sides of mountains, breaking into small pieces, increasing the amount of surface area to be weathered.
What factors contribute to deep, fertile topsoil in temperate regions?
Temperate areas have frequent changes in temperature, which leads to frost action. Mechanical weathering makes the soil thicker. Temperate regions also get enough rain to cause a high level of chemical weathering, but not so much that the nutrients are leched out of the soil. The thick soil is fertile.
How do humans increase the effects of erosion?
Humans disturb and damage rocks and soil. Construction (blasting, digging, mining) disturb rocks. Poor farming strip the plants from soil and expose them to wind erosion. Building on steep slopes causes rock fall and landslides. Deforestation causes mudslides.
Summarize weathering, erosion, and depositon
Weathering is the breaking down of rock. Erosion is the movement of the broken down rock. Deposition is when the broken down rock or sediment is laid down.