Weathering and Erosion Lecture Notes

Flashcards on weathering and erosion, including chemical and physical processes, soil formation, and control factors.

What is Physical Weathering?

The physical breakdown of rocks and minerals into smaller pieces or clasts.

What is Chemical Weathering?

The chemical breakdown of rocks and minerals via chemical reactions to produce new compounds and/or to release ions.

What are the main types of physical weathering?

Frost wedging, rock breakage, exfoliation, spheroidal weathering, and bioturbation.

What causes Frost Wedging?

Due to the expansion and contraction of water in cracks and crevices.

How does Rock Breakage occur?

Two rocks collide and break apart, or loose rocks fall from a cliff.

How does Exfoliation occur?

Occurs when intrusive igneous rock is exposed to the surface and expands due to the removal of overlying rock.

How does Spheroidal Weathering occur?

Sharp corners of rocks are knocked off during transport in a river.

How does Bioturbation affect rocks?

Biological activity disrupts rocks physically or chemically, such as tree roots cracking a sidewalk.

What does it mean for a mineral to be chemically unstable?

Some minerals are very susceptible to chemical weathering.

Which silicate minerals are more stable?

Many silicate minerals that form at low temperatures.

What factors influence weathering rates?

Rock type, climate, and the presence of water.

What is Dissolution?

A substance dissolves in the presence of water and/or acids and reverts back to ions.

Give an example of Dissolution.

Halite (table salt) dissolving in water into Sodium and Chlorine ions.

What minerals are affected by Hydrolysis/Hydration?

Feldspar minerals in acidic water, producing Kaolinite clay.

What minerals are affected by Oxidation?

Ferromagnesian minerals, such as pyroxene, in the presence of Oxygen (O2).

What happens to Iron during Oxidation?

Iron rusts and changes its oxidation state from ferrous (Fe2+) to ferric (Fe3+).

What happens to the surface area of rocks and minerals as they are physically broken down?

It increases relative to its volume, exposing more surface area to weathering.

What is Regolith?

Physical weathering by-products, minerals, etc.

What is Humus?

Organic material, such as leaf litter, that decays and releases nutrients to the soil.

What is a Soil Profile?

Represents a cross-section through a soil, with different layers called Horizons.

What are the control factors for weathering?

Climate, rock/mineral type, presence of water/acids, pre-existing soil, and time.

What is Erosion?

The removal of weathered material and/or weathering by-products by the influence of gravity.

How does Transportation of weathered by-products (sediments) occur?

Ice, water, or wind.

What is Carbonic Acid?

A weak, naturally occurring acid produced by the combination of water and carbon dioxide.

In what substances will Calcite dissolve?

A combination of carbon dioxide and water; or a combination of hydrogen ions and bicarbonate ions.

What strong acid is commonly produced by the burning of coal which contributes to acid rain?

Sulfuric acid.

Which will dissolve quicker: Cube of sugar or granulated sugar?

Granulated sugar.

What is one of the control factors of weathering?

Climate

What speeds up chemical reactions and weathering?

Presence of Water

The more available, the more weathering will occur.

Time

Erosion is the removal of weathered material due to what influence?

Gravity

What common naturally occurring acid will trigger chemical reactions?

Carbonic Acid

Carbonic acid is produced by a combination of water and carbon dioxide that form what ions?

Hydrogen ions

Carbonic acid is produced by a combination of water and carbon dioxide that form what ions?

Bicarbonate ions

Give an example of bioturbation.

Tree Roots

What is the physical and/or chemical breakdown of rocks and minerals?

Weathering

What kind of organism can secrete chemicals which could cause weathering?

Plants

What kind of organism can secrete chemicals which could cause weathering?

Animals

What is a by-product of oxidation reactions?

Dissolved Silica

What is a product of hydrolysis/hydration?

Kaolinite Clay

Oxidation occurs in the presence of what element?

Oxygen

Soil is capable of sustaining plant life and what is not?

Sediment

Sulfuric acid is a major component of what?

Acid Rain

Are weathering rates generally fast or slow?

Slow

What is weathering?

The physical and/or chemical breakdown of rocks and minerals.

Define erosion.

Removal of weathered material by gravity.

What is transportation of sediments?

Transport of weathered by-products by ice, water, or wind.

What's the impact of breaking rocks into smaller pieces?

Increases surface area for weathering.

Define regolith in the context of soil composition.

Physical weathering by-products in soil.

What is humus?

Organic material in soil.

Define a soil profile.

Section through soil.

What is the relationship between climate and weathering?

Influences weathering.

How does the presence of water and acids affect weathering processes?

Speeds up weathering.

What's the effect of time on weathering?

More weathering occurs.

What type of rock is calcite?

Calcium Carbonate

What is the weathering process that affects halite?

Dissolution

What can be caused by burning Coal?

Acid Rain

What kind of weathering makes rocks more rounded?

Spheroidal

Is frost wedging a chemical or physical process?

Physical

Is oxidation a chemical or physical process?

Chemical

What is weathering by organisms called?

Bioturbation

What comes after weathering and erosion?

Transportation

What develops during spheroidal weathering?

Weathering Rind

What are soil layers also called?

Horizons

What element is table salt?

Halite

What is formed when iron oxidizes?

Hematite

What type of mineral can be affected by hydration?

Silicate

What is hydrolysis also known as?

Hydration

What is the oxidation state of iron after it oxidizes?

Ferric

What is the oxidation state of iron before it oxidizes?

Ferrous

What is the name of the strong, industrial acid?

Sulfuric

What is the name of the weak, natural acid?

Carbonic

What is a transportation factor for weathered materials?

Ice

What is a transportation factor for weathered materials?

Wind

What is a transportation factor for weathered materials?

Water

What material is kaolinite?

Clay

How would you describe a sidewalk that is subject to bioturbation?

Uneven

Fractures can develop in what?

Rocks

Intrusive rock is initially burried by the weight and ____ of the rock above.

Pressure

What kind of animal could burrow into a rock?

Clams

What are sodium and chlorine?

Salts

Oxidation causes iron to _.

Rust

What process exposes a fresh surface?

Erosion

What new material does hydrolysis create?

Clay

What does soil sustain?

Plant life

Will cube sugar desolve faster or slower than granulated sugar?

Slower

What is increased when rock is physically weathered?

Surface Area

What is the process of chemical weathering?

Chemical Reaction

What is produced in physical weathering?

Smaller Clasts

What causes rocks to break during frost wedging?

Expansion

What is it called when over-lying rock is removed from intrusive rock?

Unloading

Smooth fractures can produce parallel .

Sheeting

Where is Half Dome located?

Yosemite

Where does spheroidal weathering often occur?

River

bioturbation often occurs due to .

biological activity

Weathering rates are generally .

slow

During dissolution, a substance __ in the presence of water and/or acids.

Dissolves

What will dissolve in carbonic acid?

Calcite

Hydrolysis affects .

feldspar minerals

Hydrolysis creates kaolinite clay and dissolves _.

Silica