Weathering, Erosion, & Soil Test

Question 1

Weathering

Answer 1

The physical breakdown and chemical alteration of rock at or near Earth’s surface

Question 2

Chemical Weathering

Answer 2

Breaks down rock components and the internal structures of minerals

The most important agent involved in chemical weathering is water (responsible for transport of ions and molecules involved in chemical processes)

Question 3

Mechanical Weathering

Answer 3

Breaking of rocks into smaller pieces. There are 4 different kinds

Question 4

Frost Wedging

Answer 4

Alternate freezing and thawing of water in fractures and cracks promotes the disintegration of rocks

Question 5

Unloading

Answer 5

Exfoliation of igneous and metamorphic rocks at the Earth’s surface due to a reduction in confining pressure

Question 6

Thermal Expansion:

Answer 6

Alternate expansion and contraction due to heating and cooling

When things are cold they expand and when things are warm they contract

Question 7

Biological activity

Answer 7

Disintegration resulting from plants and animals

Question 8

Erosion

Answer 8

The physical removal of material by mobile agents such as water, wind, ice, or gravity

Question 9

Oxidation

Answer 9

Any chemical reaction in which a compound or radical loses electrons Important in decomposing ferromagnesian minerals

any chemical reaction that involves the moving of electrons

Question 10

Hydrolysis

Answer 10

The reaction of any substance with water
Hydrogen ion attacks and replaces other positive ions

a chemical reaction or process in which a chemical compound reacts with water.

Question 11

Soil

Answer 11

a combination of mineral and organic matter, water, and air

Question 12

Regolith

Answer 12

(rock and mineral fragments produced by weathering) that supports the growth of plants

Question 13

Parent Material

Answer 13

Source of the weathered mineral matter from which soil develops.

Residual soil – parent material is the underlying bedrock (was always there)

Transported soil – forms in place on parent material that has been carried from elsewhere and deposited (put somewhere) by gravity, water, wind, or ice. Like a stream bed.

Question 14

Leaching

Answer 14

The depletion of soluble materials from the upper soil by downward–percolating water.

To pass a liquid through to carry off the soluble components.

Question 15

Briefly explain how mechanical weathering aids chemical weathering.

Answer 15

Mechanical weathering aids chemical weathering by increasing the surface area.

Mechanical weathering increases the overall surface area when it breaks down the rock into smaller fragments.

When this happens there is more surface for chemical weathering to attack the rock, allowing chemical weathering to speed up

Question 16

How does climate and a rocks characteristics affect the rate of weathering

Answer 16

Climate affects the rate of weathering because temperature and moisture are the most crucial factors.

Chemical weathering is most effective in areas of warm, moist climates.

A cold, dry climate will produce the lowest rate of weathering.

A warm, wet climate will produce the highest rate of weathering.

Rock characteristics also affect the rate of weathering because Rocks containing calcite (marble and limestone) readily dissolve in weakly acidic solutions. Also, silicate minerals weather in the same order as their order of crystallization. This happens because plants and bacteria grow and multiply faster in warmer temperatures.

Question 17

What is meant by differential weathering

Answer 17

Masses of rock do not weather uniformly due to regional and local factors resulting in many unusual and spectacular rock formations and landforms.

Weathering happens at different rates to rocks in the same area. Differential weathering can shape the land by leaving peaks of highly resistant rocks and holes or depressions where less resistant rocks have been broken down.

Question 18

What are the 4 basic components of soil? Remember, proportions can vary.

Answer 18

Soil is a combination of mineral and organic matter, water, and air.

About ½ total volume is a mixture of disintegrated & decomposed rock (mineral matter)

Humus: the decayed remains of animal & plant life (organic matter) **Plant nutrients enhance the soil’s ability to retain water. Other ½ consists of Pores spaces among the solid particles where air & water circulate. **This circulation is vital.

Question 19

What is the importance of pore spaces in soil?

Answer 19

Soil is far from “pure” water. It is a complex solution containing soluble minerals. In the pore spaces, there will be moisture for chemical reactions that sustain life. The pores filled with moisture and air provide plants with nutrients in a form that they can use. Pore spaces that are not filled with water will have air. Air provides oxygen and CO2 that allows microorganisms and plants to live in the soil.

Question 20

What is the difference between residual and transported soil?

Answer 20

Residual soil – parent material is the underlying bedrock
a soil material which is the result of weathering and decomposition of rocks that has not been transported from its original place.

Transported soil – forms in place on parent material that has been carried from elsewhere and deposited by gravity, water, wind, or ice. Like a stream bed.

Question 21

What are 4 factors controlling soil formation? Briefly explain.

Answer 21

Time: Younger soils have some characteristics from their parent material, but as they age, the addition of organic matter, exposure to moisture, and other environmental factors may change its features.

Climate: The most important factor that can shape the formation of soils. Two important climatic components, temperature, and precipitation

Plants and Animals: soil’s physical and chemical properties depend on the living things (plants and animals) that live on the surface and inside the soil.

Topography: (the arrangement of the natural and artificial physical features of an area.) Variations can lead to the development of a variety of localized soil types. There will be poor soils on the steep long slopes and richer deposits at the foot of the slopes.

Question 22

V/hat are the 5 horizons in a soil a profile? What horizons make up topsoil

Answer 22

Horizons are – zones or different layers of soil

1. O horizon – organic matter
2. A horizon – organic and mineral matter high biological activity.
3. E horizon – little organic matter
4. B horizon – zone of accumulation. In extreme cases, clay accumulation can form a very compact & impermeable layer called Hardpan.
5. C horizon – partially altered parent material

Together the O and A horizons make up the topsoil

Question 23

What are the 3 parts to the erosion process

Answer 23

1. Detachment raindrop impact; kinetic energy (splash) wind loosening soil; impact
2. Transportation of detached particles downhill, floating, rolling, splashing, or dragging
3. Deposition (where it all deposits or lands)

Question 24

What are the types of water erosion? Know the difference between them.

Answer 24

1. Sheet-splashed soil moves uniformly
2. Rill- as sheet flow becomes channels, rills are small enough to be removed by normal tillage
3. Gully: runoff water becomes concentrated enough to cut deep gullies

Question 25

How are sedimentation and chemical pollution harming our environment?

Answer 25

Sedimentation and chemical pollution. Each year in the US millions of tons of eroded soil is deposited in lakes, reservoirs, & streams. This is significant because the more sediment deposited, there is a reduction in capacity

Occasionally soil particles are contaminated with pesticides from farming.

When these chemicals are introduced to a lake or reservoir, the quality of the water becomes threatened.

Fertilizers added to soil can also make their way to rivers and streams and can create Dead Zones: excessive nutrients accelerate plant growth and leads to a depletion of Oxygen in a body of water. EX: Gulf of Mexico

The Dead Zone in the Gulf of Mexico is an area of low oxygen that can kill fish and marine life near the bottom of the sea.