Earth Sci : Exogenic and Endogenic Processes

Exogenic Processes

These are external mechanisms that happen at or near the Earth's surface; These processes wear and degrade the surface geologic features.

Solar Energy and Gravity

driving forces of the exogenic process

Weathering

the physical breakdown and chemical alteration of rock at or near Earth's surface

Mechanical Weathering

is the physical breakdown of large rocks into smaller rocks without changing its mineral compostion

Frost wedging or frost weathering

Water that enters through cracks and empty spaces of rocks expands as it freezes.

Insolation weathering or thermal stress weathering

Results from the expansion and contraction of rock caused by temperature change.

Unloading or pressure release

Occurs when the overlying rock is eroded away, causing the outer rock to expand more than the rock below it. Evident in intrusive igneous rocks.

Chemical Weathering

The process that breaks down rock through chemical changes

Oxidation

Occurs when the oxygen dissolved in water will oxidize some materials.

Hydrolysis

Breaking down complex molecules by the chemical addition of water.

Mass wasting

the downslope movement of rock, regolith, and soil under the direct influence of gravity

Gravity

The main driving force of mass wasting.

rock falls

piece of rock or a mass of rocks become dislodged and moves at free fall

landslide

sudden, fast movement of a cohesive mass of soil, rock, or regolith

Translational Slide

movement of mass of materials along a well-defined surface

Rotational Slides

descending materials move along a concave-upward curved surface

flows

movement of materials due to their water content

slurry flows

consists of a mixture of rocks and/or regolith with 20% to 40% water

Granular flows

contain 0 to 20% water, not saturated with water

human induced mass wasting

removal of the surface vegetation through urban development

human induced mass wasting

oversteeping of slopes through quarrying, open pit mining and building on steep-slopes

human induced mass wasting

adding moisture to slopes through lawn watering, leaking and draining of pools

Erosion

The process of transporting weathered sediments by agents to different places.

Water

The primary agent of erosion on Earth.

Glacier

A large, moving mass of ice.

Plucking

The process wherein fractured bedrocks are incorporated into the ice. This occurs when ice water penetrates the cracks and joints. As ice water freezes, it expands, loosens, and pulls out the rock fragments. This makes the rock fragments become part of the glacier.

Abrasion

Occurs when the ice and its load of rock fragments slide over a bedrock.

Wind

It carries dust, sand, and volcanic ash from one place to another. In dry areas, a stronger one wears away soft rocks, and polishes rocks and cliffs until they are smooth. It can also erode materials until nothing is left. In the desert, it blows sand to form sand dunes.

Solution

Materials are dissolved in water and carried along by water.

Suspension

The suspended particles are carried by a medium (air, water, or ice).

Traction

Particles move by rolling, sliding, and shuffling along eroded surface. These occur in all erosional agents.

Saltation

Particles move from the surface to the medium in quick, repeated cycles. The repeated cycle has enough force to detach new particles.

Deposition

The aggradation or accumulation of weathered sediments to create different landforms.

Decreases

Whenever stream velocity __________, the stream deposits the sediments it carries.

Alluvium

The material deposited by a stream.

Delta

Formed when water flows through distributary channels and deposit sediments at the junction of a river or sea.

Distributaries

Part of a stream that leaves the main flow.

Alluvial fan

Formed when a stream reaches a flat area (piedmont) or gently sloping plane. When velocity of a stream slows, it loses its capacity to carry sediment and deposits them at the junction of the hill and piedmont, forming fan-shaped deposits.

Flood plain

Flat, wide expanse of alluvium that covers flat areas which are prone to flooding.

Leevees

Formed by successive flood over several years.

Moraines

Layers or ridges of till. A tong pile of rocky material at the edge of a glacier is a lateral one and a pile at the middle of glacier is a medial one.

Esker

Winding ridge of sand and gravel deposited under a glacier by water melting from the ice.

Drumlins

Elongated features primarily composed of glacial till.

Kames

Conical hills formed when a stream deposits sediments in a depression on a glacier's surface.

Loess

Blanket of silt (sediment) carried by wind in suspension and deposited over broad areas.

Sand dunes

Deposits of coarse materials in the shape of hills or ridges.

Dune

General term to describe any mound or ridge of windblown sand rising to various heights of up to 50 m.

Endogenic processes

Geologic processes that occur beneath surface. It results in the reshaping of the Earth's landforms.

Radioactive decay

The heat energy of this is the main driving force of endogenic processes.

Continental drift

Theory that all continents were originally part of a huge landmass or supercontinent called Pangaea.

Alfred Wegener

Proposed in 1912 the theory of Continental Drift.

Plate tectonic theory

A theory which proposes that Earth's rigid lithosphere consists of seven large and numerous smaller segments called plates.

Plate boundary

A fracture separating one plate from another.

Convergent plate boundary

A type of plate boundary in which two plates move toward each other. There are three types: oceanic-continental, oceanic-oceanic, and continental-continental.

Subduction zones

Convergent boundaries are called __________.

Divergent plate boundary

A type of plate boundary in which two plates move apart. As they move away, the fractures formed are filled with hot magma via upwelling.

Transform plate boundary

A type of plate boundary in which plates slide horizontally past one another.

Deformation

The change in the original shape and size of a rock. It is caused by tectonic forces. The type experienced (strain) by a rock depends largely on the type of tectonic force (stress) exerted.

Folding

Occur when rocks are pushed toward each other from opposite sides.

Anticline fold

Upward arching fold.

Syncline fold

Downward arching fold.

Faulting

Fractures in the crust along which displacement has occurred.

Dip-slip fault

A type of fault that occurs when the movement of the two blocks is vertical. It involves two types: normal and reverse.

Normal fault

The hanging wall block moves down relative to the foot wall block.

Reverse fault

The hanging wall moves up relative to the foot wall block.

Strike-slip fault

Occurs when the dominant displacement is horizontal and parallel.

Volcanism

A phenomenon in which molten rocks (magma) are erupted from Earth's interior onto the surface.

Volcano

A vent or a series of vents on Earth's crust. There are three types: active (erupted within in the last 600 years or having erupted within the last 10000), dormant (have not erupted for more than 1000 years but have potential to activate), and extinct (have not erupted within the last 10000 years, and are unlikely to erupt again).

Convergent Volcanism

As two tectonic plates collide, the slabs of rocks descend into the mantle. Magma at the subduction zone occurs due to the following conditions: increased temperature due to friction, addition of water to the asthenosphere, pressure-relief melting or decompression melting. Magma generated is andesitic.

Divergent Volcanism

Occurs when tectonic plates move apart and new ocean floor is created as magma rises up to fill the gap. Magma generated is basaltic.

Hot Spots

These are columns of rising mantle materials that begin to melt as they rise to lower pressure and shallower depths.

Intrusive vulcanicity

Occurs in the process in which pluton (intrusive igneous rock) is made.

Extrusive vulcanicity

Occurs when magmatic bodies are expelled onto the surface.

Gases

Volcanic eruption emits this into the air. Includes a variety such as water vapor, carbon dioxide, carbon monoxide, sulfur dioxide, and many more.

Lava

Magma that flows out to the Earth's surface.

Pyroclasts (or tephra)

Solid particles thrown out during volcanic eruptions. Can be categorized in the following manner: volcanic blocks, lapilli, volcanic ash, volcanic dust.

Earthquake

A sudden motion of the Earth. It is divided into three focuses: shallow (long and close to the surface), medium (occur along transform and divergent boundaries), and deep (most destructive type that occurs along subduction zones).

Focus or hypercenter

The point of origin of an earthquake.

Epicenter

Point on Earth's surface directly above the focus.

Seismograph

Instrument used in detecting and measuring earthquakes.

Seismogram

The record made by a seismograph is called _____.

Seismic waves

Waves that travel through rocks.