Earth Science : MOD 3

geological processes of earth

Describe the natural forces that influence the shape and structure of the planet

geological processes of earth

Examples are plate tectonics, erosion, weathering, and sedimentation are among examples of forces that significantly affect earths surface

1. exogenous processes (external)

2. endogenous processes (internal)

two categories of geologic processes

Exogenous processes on earth

Occur on or near the surface of the Earth

exogenous processes on earth

Are natural occurrences that leave significant changes on the landscape and even in the ecosystem of an area

1. weathering

2. Erosion

3. Mass wasting

4. Sedimentation

types of exogenous processes

weathering

It is the disintegration of rocks, soils, and minerals together with other materials through contact with earth’s subsystems

weathering

The breakdown of soils and rocks happens on the spot

1. physical weathering

2. Chemical weathering

Two types of weathering

physical weathering

Is the breakdown of rocks by mechanical forces concentrated along rock fractures

physical weathering

can occur due to changes, whether sudden or not, in temperature, pressure, frost, etc.

physical weathering

Also known as, mechanical weathering

physical weathering

The process by which rocks breakdown or change shape and texture by external forces

physical weathering

Unlike chemical weathering, this does not change the chemical composition of a rock

physical weathering

Not only nature can do human activities could also contribute

1. Abrasion weathering

2. Exfoliation weathering

3. Frost wedging

4. Salt crystallization

5. Thermal expansion

6. Biological activities/root wedging

types of physical weathering

Abrasion weathering

Rocks are broken down into smaller pieces by forces like wind, water, and even glaciers

Abrasion weathering

Forces can cause this by grating against rock fragments, known as clasts

Abrasion weathering

When rocks scrape or grind against each other. This is caused by the friction between the rocks and moving particles from wind, wave, etc.

exfoliation weathering

Occurs most often with igneous rocks

exfoliation weathering

flaking of outer layers of rocks

exfoliation weathering

Is a form of mechanical weathering in which curved plates of rocks are stripped from rock below

unloading

A process that happens as layers on the outside of a rock flake or fall off

exfoliation weathering

Also known as onion skin weathering

onion skin weathering

Often occurs in hot areas like deserts where the temperature is often high in the daytime and eventually the temperature decreases in the night

exfoliation weathering

During daytime, the rocks are exposed to the sun which causes the rocks to expand. However, during the night the rocks contracts because of the cooler temperature. This process is continued and overtime, the surface of the rock begins to flake off

onion skin weathering

Is a geological process that occurs when rocks outer layer peels of due to extreme variations in temperatures

Frost wedging

Happens when water goes inside a crack and freezes

Frost wedging

Water gets into fractures and then freezes, expanding the fracture a little. When the water thaws it seeps a little farther into the expanded crack.

Salt crystallization

Occurs in coastal and desert regions when water evaporates, leaving salt crystals behind

Salt crystallization

Happens when the crystals expand, they exert pressure on surrounding rock, eventually breaking the rock and leaving holes in the rocks surface

Haloclasty

A process in which crystals break the rock and leave holes in the rock surface resulting a honeycomb appearance

thermal expansion

Minerals expand and contract when heat fluctuates

Thermal expansion

happens when rock surface heats up and expands, then rock surface cools and contracts, then joint form in the outer part of the rock and causes broken rocks when back to original form

biological activities/root wedging

If from living organisms, it can also cause physical weathering

Root wedging

A process where in roots from large plants grow into small breaks in rocks

Root wedging

It is when a plants root starts to grow in a crack of a rock, it then exerts a powerful force that can slowly fry the rock

burrowing animals

Such as smalls, rabbits, and worms that causes physical weathering by disturbing dirt and soils as they dig

Burrowing animals

They can also create space for water flow to further weathering processes

Chemical weathering

What is the process by which rocks breakdown by chemical reactions

ex. honeycomb appearance of rocks

Chemical weathering

New or secondary minerals develope and sometimes replace the original properties of the minerals in the original rock or soil during this

Chemical weathering

Oxidation and hydrolysis are chemical processes that contributed to these changes

Chemical weathering

May cause the structure of rocks to be weaker, which may put them at a risk for substantial mechanical weathering

erosion

Is the process by which earth surface is worn away by wind, water or ice

Happens in elevated areas with the presence of Gravity

erosion

The process of this moves rock debris or soil from one place to another

erosion

Takes place when there is rainfall, surface runoff, flowing river, seawater intrusion, flooding, freezing, and thawing, hurricane wind, etc.

erosion

These are forces of nature , whether violent or passive, capable of scraping and exfoliating the surface and exposing the layers underneath it. Movement of animals during migration or stampede can also cause this.

Erosion

human activities also causes this, like deforestation, overgrazing of farm animals, and urbanization

Erosion

can cause massive deterioration and destruction of surface structure and foundation which may be unsafe for buildings and communities

1. Splash erosion

2. Sheet erosion

3. Rill erosion

4. Gully erosion

5. Wind erosion

6. Food plain erosion

Types of Erosion

Splash erosion

starts with a fall of rain, which might be why its sometimes called raindrop erosion

Splash erosion

happens when a raindrop hits the soil and dislodges particles of soil, splashing them up and away