Unit 4 Chapter 10 Weathering and Soil Formation Flashcards
the process by which rock materials are broken down by the action of physical or chemical processes
weathering
a breakdown of rock into smaller pieces by physical means
mechanical weathering
the grinding and wearing away of rock surfaces through the mechanical action of other rock or sand particles
abrasion
the process by which rocks break down as a result of chemical reactions
chemical weathering
rain, sleet, or snow that contains a high concentration of acids
acid precipitation
Name three things that can cause abrasion.
wind, water, and gravity can cause abrasion
frost action
one type of mechanical weathering caused by alternating freezing and thawing of soil and rock.
ice wedging
one type of frost action. Starts when water seeps into cracks during warm weather. When the temperature drops, the water freezes and expands, causing the ice to push against the sides of the crack and the crack to widen.
How do plants cause weathering?
Plants often send their roots into existing cracks. As the plant grows, the force of the expanding root causes the crack to widen.
List 3 animals that can cause weathering.
ants, mice, worms, rabbits, coyotes, gophers, moles, etc
acid precipitation
precipitation is normally acidic, however acid precipitation contains more acid than normal. This high level of acidity can cause very rapid weathering of rock.
acids in groundwater
In certain places the groundwater contains weak acids such as carbonic or sulfuric acid. These acids react with rocks in the ground such as limestone. A chemical reaction occurs dissolving the limestone. Caverns are formed from the eating away of the limestone.
lichens
consist of fungi and algae. Contribute to chemical weathering.
What can cause oxidation?
Oxidation occurs when oxygen combines with an elements to form an oxide. Rust is an example of chemical weathering caused by oxidation.
List 3 things that cause chemical weathering of rocks.
Water, acid, and air
Describe 5 sources of chemical weathering.
water - water dissolves rock over a long period of time
acid precipitation - the higher level of acidity can cause very rapid weathering of rock
acid in groundwater - acid in groundwater dissolves limestone and may form caverns
acids in living things - lichens produce acids that can slowly break down rock
air - oxygen in the air causes certain elements such as iron to oxidize.
the process by which softer, less weather resistant rocks wear away and leave harder, more weather resistant rocks behind
differential weathering
How does an increase in surface area affect the rate of weathering?
As the surface area increases, the rate of weathering also increases
Why would a mailbox in a warm, humid climate experience a higher rate of weathering than a mailbox in a cold, dry climate?
Warm, humid climates have higher rates of weathering because oxidation happens faster when temperatures are higher and when water is present.
Why do mountaintops weather faster than rocks at sea level?
Mountains weather faster because they are exposed to more wind, rain, and ice, which are agents of weathering.
a loose mixture of rock fragments, organic material, water, and air that can support the growth of vegetation
soil
a rock formation that is the source of soil
parent rock
the layer of rock beneath soil
bedrock
the soil quality that is based on the proportions of soil particles
soil texture
the arrangement of soil particles
soil structure
dark, organic material formed in soil from the decayed remains of plants and animals
humus
the removal of substances that can be dissolved from rock, ore, or layers of soil due to the passing of water
leaching
What is soil formed from?
Soil is formed from parent rock, organic material, water, and air.
Why is the topsoil in tropical rain forests thin?
Heavy rains leach precious nutrients into deeper layers of soil, resulting in a very thin layer of topsoil.
What climate has the most productive soil?
Temperate climates have the most productive soil.
What property of soil influences soil moisture?
Soil structure
What property of soil influences how nutrients can be dissolved in soil?
soil fertility
What is the difference between residual and transported soils?
Residual soil remains above its parent rock. Transported soil is blown or washed away from its parent rock.
Which climate has the most thick, fertile soil?
temperate climate
How does soil temperature influence arctic soil?
In arctic climates, weathering occurs very slowly. At low temperatures, decomposition of plants and animals happens more slowly. Slow decomposition limits the amount of humus and nutrients in the soil.
a method to maintain the fertility of the soil by protecting the soil from erosion and nutrient loss
soil conservation
the process by which wind, water, ice, or gravity transports soil and sediment from one location to another
erosion
Why is soil important?
Soil provides nutrients to plants, houses for animals, and stores water.
What can soybeans and peanuts do for nutrient-poor soil?
They restore important nutrients to the soil and provide cover to prevent erosion.
How does crop rotation benefit soil?
If the same crop is grown year after year in the same field, certain nutrients become depleted. To slow this process, a farmer can plant different crops which will use up less nutrients or different nutrients from the soil.
List different methods of soil conservation and describe how each prevents the loss of soil.
contour plowing - helps prevent erosion from heavy rains
terracing - prevents erosion from heavy rains on steep hills
no-till farming - prevents erosion by providing cover that reduces water runoff
cover crop - crops that are planted between harvests to replace certain nutrients and prevent erosion (soybeans)
crop rotation - changing what crop is planted in which field to reduce nutrient depletion.
