Weathering and Soil

Each layer of a soil profile is called a __________.

horizon

which horizon of a soil profile is litter usually found?

horizon A

which horizon of a soil profile does leaching normally occur?

horizon B

which horizon of a soil profile is the parent material usually found?

horizon C

Decayed organic material turns into a dark colored material called ___________.

humus

agricultural cultivation

increased farming removes the plant cover, leaving solid open to wind and water erosion

A soil's composition is dependent on weathering because __________.

it contributes sediment to the soil

Why is soil erosion more common in areas that lack adequate vegetation?

because plant roots help keep the soil in place

Why is ice wedging most obvious in the mountains?

because the temperature changes in the mountains allow for the repeated freezing and thawing of water caught in cracks of rocks

carbonic acid

formed from carbon dioxide and water and plant acids can react with minerals to weather rock

Erosion is more common on __________.

steep slopes

Effects of weathering

surface process breaks down rock into small pieces called sediment which later can harden into new sedimentary rock

________ is a method in which level-topped areas are built into steep-sided hills.

terracing

composition of soil-

the ingredients that make up soil

Climate affects soil types; for instance, prairie soils have __________.

thick, dark, A horizons because of all the grasses that contribute organic materials

how long does formation of soil take?

thousands of years

chemical weathering is more rapid than mechanical weathering in ___ climates

warm

ice wedging

water enters cracks and freezes and expands breaking rocks apart

Surface processes that work to break down rock are called__________.

weathering

overgazing results?

when animals graze till almost all ground cover disappears

How does grazing affect soil?

-Grazing can improve soil quality due to organic matter that livestock leaves behind. -Grazing can be used in place of plowing in no-till farming.

Horizon C

-bottom soil layer -very little organic matter and isn't strongly affected by leaching -contains rock (parent material of the soil)

chemical weathering works ____ and slower in ____ climate

-heat -slower

how can soil become different from the rock underneath it?

-if weathering has occurred longer -if glaciers have carried the sediments from one place to another -if water has carried sediments from upstream

large rocks are ___ exposed to surface area to weather ___

-less -slowly

preventing soil erosion?

-managing crops by farmers planting plant shelter belts of trees to break the force of the wind -contour farming (reduces soil erosion by planting along the contours of slopes)

____ and ___ weather very ____. Unlike ____ that hardly weathers.

-marble and limestone -quickly -quartz

horizon B

-middle soil layer -aka subsoil -contains less humus ans lighter color than horizon A

Small pieces of rock have ____ surface area than _____ pieces of rock and small pieces _______ faster

-more -larger -weather

small rocks are ___ exposed to surface area to weather ___

-more -quick

How do farmers attempt to manage crops to reduce soil erosion?

-plant shelter belts of trees -use animals to graze over vegetation instead of plowing -practice no-till farming

How do construction sites attempt to reduce erosion?

-they cover exposed ground with plastic to prevent wind erosion -they spray exposed soil with water to prevent wind erosion. -they replace topsoil that has been removed during construction.

horizon A

-top layer of soil -may be covered with organic litter that may turn into humus -fertile layer with more humus and less rock

Soil is a mixture of __________.

-weathered rock and water -decayed organic matter and oxygen -mineral fragments

How does climate affect chemical and mechanical weathering?

Chemical weathering occurs more rapidly in warm, wet climates, and mechanical weathering occurs more in cold climates.

How can rock type within the parent rock affect the type of vegetation that grows there?

Different rocks provide different nutrients for plant growth.

How does agricultural cultivation contribute to soil erosion?

Farmers who plow their land uproot plant roots which hold soil in place.

How is surface area related to chemical weathering?

Increased surface area allows for more interactions of rocks with water and oxygen.

How does soil erosion affect topsoil?

It washes it away.

How do chemical and mechanical weathering differ?

Mechanical weathering occurs when rocks are broken by physical processes, and chemical weathering happens when chemical reactions dissolve minerals.

Why does clearing tropical rain forests have an adverse effect on soil quality?

The soil is only good for farmers for a few years before the nutrients are gone because the soil is almost infertile below the first few centimeters.

soil particles with small spaces can be filled by?

air or water

When water mixes with carbon dioxide in the air, it forms __________.

carbonic acid

oxidation

chemical process that occurs when iron is exposed to oxygen in the air (rust)

chemical weathering

chemical reactions dissolve minerals in rocks or change them to different minerals

small particles of sediment

clay,silt, and sand

what does urban construction do?

clears land of vegetation and removes soil

formation of soil is influenced by?

climate, slope, types of rock, types of vegetation, and length of time that the rock has been weathering

mechanical weathering is more rapid than chemical weathering in ____ climate

cold

humus

decaying dark colored plant and animal material

what does time affect? how?

development because the longer the weathering, less soil resembles the parent rock

soil types

differ in different places

soil profile

made up of different layers of soil

causes and effects of soil erosion-

many human activities disturb nature balance

Leaching

minerals travel from A to B horizon. (occurs between A and B horizon)

soil

mixture of weathered rock, decayed organic matter, mineral fragments water and air

effects of climate-

pattern of weather that occurs over time

mechanical weathering

physical processes break rocks into fragments with the same chemical makeup and characteristics are original rock (example: tree-roots)

what causes mechanical weathering?

plant roots and burrowing animals

soil erosion or loss is important because

plants don't grow

soil on steep slopes develop ____? why?

poorly because sediment does not have time to build up before it's carried downhill

A human activity that contributes to soil erosion is __________.

raising livestock

forest harvesting

removes forest vegetation which increases erosion and particularity damage

____ ____ can effect rates of weathering

rock types

parent rocks affects?

soil formation and type of vegetation that grows in that region

why is it important to prevent or reduce soil erosion?

soil takes many years to develop: plants can't grow well without fertile soil

glaciers can deposit?

soil that did NOT form from the bedrock beneath it