Unit 2: Landscapes and Surface Processes (Science 9)

Rock Cycle

the process by which rocks of one kind change into rock of another kind

Types of Rocks:

1. Igneous

2. Metamorphic

3. Sedimentary

Rocks can change by these physical processes:

1. cooling

2. weathering and erosion

3. compacting and cementation

4. heat and pressure

5. melting

The Rock Cycle Process:

1. Stars with molten rock (magma). When it cools and hardens, it forms igneous rocks. This process is called cooling, crystallization, or solidification.

2. Weathering and erosion break the original rock into smaller pieces (sediment). Sediment is then transported by rivers, wind, and glaciers and deposited elsewhere where buried and compacted and cemented. This process is called lithification.

3. Sedimentary rock can get buried deep and be exposed to heat and pressure, where, overtime, it can transform into metamorphic rock.

4. These metamorphic rocks may be heated to the point where they melt again and form into igneous rock.

Rock Cycle: Weathering and Erosion

Weathering is the breakdown of rocks into smaller particles due to natural forces like wind, water, and temperature changes.
Erosion is the movement of these weathered particles by agents such as water, wind, or ice.

Weathering breaks down a large rock into smaller pieces in the same location, erosion moves the small rocks (sediment).

Rock Cycle: Transportation and Deposition

Transportation is the process of moving weathered and eroded material (sediment) from one place to another by natural forces like wind, water, or ice.
Deposition occurs when these transported materials settle and accumulate in a new location, forming layers of sediment.

Eroded particles are transported via rain, streams, rivers, and oceans until the current isn’t moving fast enough to keep the rock particles moving so it sinks and forms a layer of sediment (deposition).

Rock Cycle: Compaction and Cementation

Compaction: the process where layers of sediment are pressed together under the weight of overlying layers, reducing the space between particles and causing them to become more tightly packed.

Cementation: process occurs when minerals dissolved in water crystallize and act as a glue, binding the compacted sediment particles together to form solid rock.

-start of burial process

Rock Cycle: Metamorphism

over long periods of time, sedimentary and igneous rock gets buried deep underground, usually cause of tectonic plates. The rock gets exposed to high heat and pressure, which changes them into metamorphic rock.

-Usually happens at tectonic plate boundaries

Rock Cycle: Rock Melting

Metamorphic rock underground melt into magma. When a volcano erupts, magma comes out of it (called lava o the surface). As the lava cools, it becomes igneous rock and the cycle starts again.

Igneous Rocks

formed when hot magma is rapidly cooled (granite, obsidian, pumice are all common types of igneous rocks)

Sedimentary Rocks

formed by layers of sediment being mixed and compressed for long periods of time (limestone, sandstone, shale are common types of sedimentary rocks

-often have fossils because plants and animals get buried with the layers of sediment

Metamorphic Rocks

combination of rock types being compressed together by high pressure and high heat (Schist, shale, gneiss are common types of metamorphic)

-usually more grainy and hard than other types

Cohesion

water molecules stick to other water molecules by hydrogen bonding

Adhesion

water molecules stick to other polar molecules by hydrogen bonding

Surface Tension

a measure of how hard it is to break the surface of a liquid

Properties of Water

1. has a high specific heat - large amount of energy required to change the temperature of water (takes a long time to heat/cool)

2. solid water is less dense than liquid water. ice floats because hydrogen bonds are more '“ordered” making ice less dense. Water reaches its greatest density at 4 Celcius.

3. water is a good solvent - dissolves polar molecules and ions

Solid - Liquid

Melting (absorbs heat)

Liquid - Gas

Evaporation (absorbs heat)

Gas - Liquid

Condensation (releases latent heat)

Liquid - Solid

Freezing (releases latent heat)

Gas - Solid

Deposition (releases latent heat)

Solid - Gas

Sublimation (absorbs heat)

Polarity

means that a molecule has two different ends: one end is slightly positive, and the other end is slightly negative. This happens because the electrons in the molecule are not evenly shared, creating a "pull" on the molecule.

Hydrological Cycle (Global Water Cycle)

• one of the most important processes in the world

• describes the storage and movement of water between the: biosphere, atmosphere, lithosphere, and hydrosphere

• composed of 8 components: evaporation, transpiration, sublimation, condensation, precipitation, run-off, infiltration and precipitation, and ground-water flow

Evaporation

process where liquid water turns into water vapor (gas) due to heat, usually from the sun.

Transpiration

process where plants release water vapor into the air through small openings in their leaves.

Sublimation

the process where a solid turns directly into a gas without becoming a liquid first.

Condensation

when water vapor rises, it cools slightly and condenses on dust particles in the air, then becomes liquid

Precipitation

the process where water falls from the atmosphere to the Earth's surface in the form of rain, snow, sleet, or hail.

Run-Off

the portion of precipitation which makes its way toward stream, channels, lakes, or oceans.

-occurs when the rate of precipitation exceeds the rate that water can infiltrate the soil

Infiltration

the process where water soaks into the ground and moves through the soil.

Groundwater

water that exists beneath the Earth's surface, filling the spaces between rocks and soil.

Carbon Cycle

the process that moves carbon between plants, animals, and microbes

• earth doesn’t gain or lose carbon

• carbon moves constantly

• most of earth’s carbon is stored in rocks and sediments. the rest is in the ocean, atmosphere and living organisms

• fundamental building block of life

• crucial factor is earth’s temperature

Carbon Sources

releases carbon into the air

• respiration by living organism

• ocean surface'

• decomposition of organic matter

• volcanic eruptions

• burning fossil fuels

• deforestation

• weathering

Carbon Sinks

hold carbon and keeps it from entering the air

• photosynthesis

• absorption by oceans

• formation of fossil fuels

• rock, soil, and sediment formation

• oceans (deep water)

• weathering

Photosynthesis

the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce their own food (glucose) and release oxygen.

-removes carbon dioxide from atmosphere

Respiration

living organism break down glucose for energy, then releases CO2 back into the atmosphere.

-occurs in both plants and animals

Decomposition

breakdown of dead organic matter. releases CO2 into atmosphere and soil

-important for nutrient cycling in ecosystems

Ocean-Atmosphere Exchange

the transfer of gas back and forth between a liquid and the atmosphere

Carbon Cycle in Terrestrial Ecosystems

• forests and and grasslands are major carbon sinks

• soils contains large amounts of organic carbon

Carbon Cycle in Aquatic Ecosystems

• oceans are the largest ocean sinks in the world

• phytoplankton play a crucial role in carbon absorption

• ocean acidification is a result of increased CO2 absorption

Carbon Cycle; Short Term

• rapid exchanges of carbon

• driven by: photosynthesis, respiration, decomposition, and ocean-atmosphere exchange

• examples: living organisms, soil organic matter, ocean surface water, atmosphere

Carbon Cycle'; Long Term

• involves geological processes that store and release carbon over long periods of time'

• carbon is primarily stored in rocks, deep ocean sediments, and fossil fuels

• major processes: carbon burial and sedimentation, fossil fuel formation, rock weathering, and volcanic eruptions

• Examples: limestone and other carbonate rocks, fossil fuels (coal, oil, natural gas), and deep ocean sediments

Human Impacts on the Carbon Cycle

• burning fossil fuels increases atmospheric CO2

• deforestation reduces carbon storage capacity

• agricultural practices affect soil carbonate content

Earth’s Cycles

1. Rock Cycle

2. Water Cycle

3. Carbon Cycle

Water Cycle and Rock Cycle

-Water erodes rocks through weathering and erosion. Water transports sediments to new locations, contributing to sedimentary rock formation.

-water is involved in chemical weathering, dissolving minerals, and altering rocks

-water infiltrates earth’s crust, playing a role in metamorphism and igneous processes

Carbon Cycle and Rock Cycle

-carbon is stored in rocks (majority in sedimentary rocks like limestone - result of ancient plant and animal remains that were compressed over time)

-volcanic eruptions release CO2 from magma

-over time, carbonates form sedimentary rocks that can be subducted and start the rock process again

Water and Carbon Cycle

-rainwater absorbs CO2 from the air forming acidic rain which weathers rock (removes CO2 from atmosphere)

-oceans absorb CO2, helping regulate climate while supporting marine life that contributes to carbonate rock formation

All Three Cycles Working Together

• plate tectonics drive the rock cycle, moving carbon-storing rocks into the mantle and releasing CO2 through volcanoes

• Weathering and erosion (water cycle) break down rocks, helping transfer carbon into oceans

• Carbon sinks in sedimentary rocks influence long-term climate regulation

Rocks are Classified by:

1. how they are formed

2. their composition

3. texture

How is Igneous Rock Formed?

Solidification of molten rock (magma)

How is Metamorphic Rock Formed?

recrystallization with an increase of of temperature and/or heat

How is Sedimentary Rock Formed?

compaction and cementation of buried sediments

Igneous Rocks; Felsic

light colored rocks that are rich in elements such as aluminum, potassium, silicon, and sodium

Igneous Rocks; Mafic

dark colored rocks that are rich in calcium, iron, and magnesium - poor in silicon

Igneous Rocks; Intrusive

Magma - takes longer to cool, giving mineral crystals more time to grow; course crystals (large)

Igneous Rocks; Extrusive

Lava - cools quickly with little to no crystals; fine crystals (or none)

Uplift

the geological process where Earth's crust is raised or pushed upward due to tectonic forces, bringing rocks from deep within the Earth to the surface.

Strata

layers of rock

Stratification

the process in which sedimentary rocks are arranged in layers

Sedimentary Rocks; Clastic

made of fragments of rock cemented together with calcite or quartz - commonly referred to as Breccia (sediments are larger and more distinguishable)

Sedimentary Rocks; Chemical

minerals crystallize out of solution to become rock

Examples:

• Limestone - composed primarily of calcium carbonate. forms from the accumulation of shells, corals, algal and fecal debris

• evaporation of seawater leaves behind rock salt which, over time, compacts

Sedimentary Rocks; Organic

remains of plants and animals

Example:

• coal - forms from the accumulation, preservation, compaction, cementation, and of plant materials, usually in a swamp environment

Metamorphic Rocks; Foliated

have “layers” of crystals formed by recrystallization where minerals align themselves under high pressure

Metamorphic Rocks; Non-Foliated

minerals are not aligned because they were not subject to high directional pressure

Contact Metamorphism

heated by nearby magma - increased temperature changes the composition of a rock, minerals are changed into new minerals

Regional Metamorphism

occurs when large areas of rock are subjected to high pressure and temperature, typically due to tectonic forces, such as the collision of tectonic plates. This process often results in the formation of metamorphic rocks that have a foliated texture

Examples:

• Schist

• gneiss

• slate

Weathering breaks rock into:

1. Pebbles

2. Sand

3. Silt

4. Clay

Mechanical (physical) Weathering

the physical breakdown of rocks into smaller pieces without changing their chemical composition, often caused by factors like temperature changes, water, and wind.

Chemical Weathering

the process where rocks are broken down or altered through chemical reactions, often involving water, air, or acids, which change the minerals in the rock.

Physical Weathering Causes

• gravitational force

• expansion force of temperature

• exfoliation

• frost wedging

• water pressures

• burrowing

• wedging

• human activities

• plant roots

Chemical Weathering Characteristics

• solution

• hydration

• oxidation

• reduction

• carbonation

Signs of Chemical Weathering

1. color changes

2. change in mineral composition

3. surface pitting or etching

4. formation of residual materials

5. altered rock texture

6. formation of oxidation products

7. cracks and fractures

Signs of Physical Weathering

1. visible cracks and holes in rocks

2. rounded pebbles from abrasion

3. exfoliation where rock layers peel away

4. scattered sediement

Plants: Root Pry

as roots grow, they cause rocks to split (mechanical)

Animals

burrowing animals loosen and push sediment to the surface where it can be weathered (mechanical)

Ice Wedging

Water expands as it freezes - the force of expansion causes rock to split apart (mechanical)

Natural Acids: Carbonic Acid

rainwater reacts with carbon dioxide in the air or soil - breaks down calcite, limestone, marble, and copper found in some rocks (chemical)

Oxygen: Oxidation (rusting)

oxygen with water dissolve iron minerals - turns rock brownish yellow - turns metal to rust (chemical)

Exfoliation

process where rock surfaces break off in sheets or layers - causes by pressure release/temperature changes (mechanical)

Hydration

rock minerals dissolve in water, changing the chemical make up of a rock (chemical)

Abrasion

the breakdown of rocks by the collision of sediments carried by moving wind or water (mechanical)

Gravity

material moving down a slope, rocks collide against each other and against the sides of the slope (mechanical)

Air Pollution

power plants and cars produce gases such s sulfur dioxide and nitric oxide, makes rainwater more acidic, breaks down calcite, limestone, and marble (chemical)

Factors that Affect the Rate of Weathering

1. surface area

2. mineral composition

3. climate (temperature and humidity)

4. pollution

Rates of Weathering; Surface Area

weathering occurs on the surface - more surface exposed means faster weathering

Rates of Weathering; Mineral Composition

some minerals are more resistant than others

Rates of Weathering; Climate Conditions

• warm, wet climates favor chemical

• cold, wet climates favor mechanical

• dry will have more mechanical

Rates of Weathering; Pollution

• pollution speeds up weathering

• carbon dioxide and other gases dissolve rainwater, forming acidic rain

• acidic rain causes rocks and minerals to dissolve faster

Agents of Erosion

• flowing water

• moving ice

• waves

• gravity

• wind

Wind Erosion

carries away rocks - responsible for deserts such as the Sahara and Gobi

• most effective in loose material

• occurs in area with no vegetation (rainfall)

Water Erosion

moving water picks up and transports sediments along streams, rivers, coasts, and deep oceans

• most influential force in erosion

• transports large objects with fast moving water

Wave Erosion

transfer of energy resulting in relentless pounding of water

• energy of waves and chemicals contained in the water weather and erode the rock off the coastline

Gravitational Erosion

Mass Movement - downward movement of rock and sediment, due primarily to the force of gravity

-streams and glaciers

-moves material from high to low elevation

Glacial Erosion

ice - moves and carries, grinding the rocks beneath the glacier

Deposition

laying down of sediment that has been transported by a medium such as:

1. Wind

2. Water

3. Ice

Deposition; Wind

wind speed can be related to variations in heating and cooling

Deposition; Water

running water enters a, fairly still large body of water and its speed decreases

Deposition; Ice

glacial flows of ice - become slower when the ice begins melting

Abraison

the wearing away of a surface through friction or the impact of particles, water, or ice