Download Earth Processes vocab and notes

Science Vocabulary Terms: Earth Processes
The vocabulary quiz on Earth Processes terms will be
Tuesday, November 15, 2016.
1. Landform: a physical feature on Earth’s surface
2. Weathering: the process of breaking rock into soil, sand, and other tiny pieces
(sediment)
3. Erosion: the process of moving sediment from one place to another
4. Deposition: the process of dropping, or depositing, sediment in a new location
5. Plate: a rigid (unbending) block of crust and upper mantle rock
6. Volcano: a mountain formed by lava and ash
7. Earthquake: a shaking of the ground caused by the sudden release of energy in
Earth’s crust
8. Fault: a place where pieces of Earth’s crust move
9. Constructive process: an Earth process that raises or builds up the surface
features of the Earth
10. Destructive process: an Earth process that lowers or tears down the surface
features of the Earth
Earth Processes Notes

Earth undergoes many processes that can change the surface features. The processes we will discuss
may be classified as constructive or destructive depending on whether it creates or destroys surface
features. A constructive process is an Earth process that raises or builds up the surface
features of the Earth. Deposition, volcanic eruptions, and earthquakes are usually examples of
constructive processes. A destructive process is an Earth process that lowers or tears down the
surface features of the Earth. Weathering, erosion, and organisms can exhibit destructive forces
on surface features.

Changes to Earth’s surface

Landforms are physical features on Earth’s surface. Landforms change due to forces like wind,
water, and ice but also because of movement inside the Earth.

Weathering is the process in which rock is broken down into smaller pieces called sediment.
Weathering can be a physical process caused by pushing, pulling, rubbing, or temperature changes. It
can also be a chemical process caused by chemicals released due to human activity.

Erosion is the process of moving sediment to a new place. Land can be eroded by gravity, glaciers,
running water, waves, or wind. Gravity pulls loose rock and soil downward, creating mudslides or
landslides.

Once sediment has been moved, it is dropped off, or deposited, during the process of
deposition.

Water can weather rock in several ways:
1) as a fast-flowing body of water like a river
2) as ocean waves crash into cliffs, causing them to weather and erode
3) as it seeps into cracks in rocks and freezes, causing the rock to break
4) as acid rain that can dissolve rock
5) by tumbling rocks against each other, smoothing and rounding the rocks’ edges
Wind erodes sediment by moving it from place to place. Dry sediment erodes more easily than soil or
damp rock.
Ice also changes landforms. Ice can expand and break rock. Also, glaciers erode sediment and
deposit it in a new location. Glaciers create U-shaped valleys.



Mountains, Volcanoes, and Earthquakes

The Earth is made of layers that differ in composition, thickness, and temperature:
1) Crust: the thin, outer layer of solid rock.
2) Mantle: the layer of rock below Earth’s crust. The mantle is solid and molten rock.
3) Core: the center layer of the Earth. The core is divided into two sections: the outer core
and the inner core. The outer core is believed to be liquid metal while the inner core is
believed to be solid metal. The inner core is solid due to intense pressure that prevents
melting.

Earth’s surface is made up of many rigid (firm) blocks of crust and upper-mantle rock called
plates. There are twelve major plates that fit together like a puzzle. These plates float on the soft
mantle rock below, causing plates to move a few centimeters every year. The theory of plate
tectonics explains how forces deep within the Earth can cause seafloors to spread and continents to
move.

Plate movement causes landforms to change. Plate movement typically occurs at plate
boundaries.
1) Divergent boundaries -- where new crust is created as the plates pull away from each other.
Seafloor spreading is caused by divergent boundaries. The Mid-Atlantic Ridge is being created
this way.
2) Convergent boundaries -- where crust is destroyed as one plate dives under another. This could
be continental-continental convergence or continental-oceanic convergence. The process of
subduction occurs when continental and oceanic plates collide, causing the continental plate to
move up and over the oceanic plate. This can cause volcanoes to erupt to create new land. Think of
this as nature’s way of recycling crust.
3) Transform boundaries -- where crust is neither produced nor destroyed as the plates slide
horizontally past each other.

A volcano is a mountain made from the buildup of lava and ash. Lava is magma that has reached
Earth’s surface. Magma is molten (melted) rock found in Earth’s mantle. Volcano chains form
where continental and oceanic plates collide. While most volcanoes are found where plates meet,
volcanoes can also from in the middle of a plate in an area called a hot spot.

There are different types of volcanoes:
1) Shield volcano: covers a broad area and has a gentle slope made mostly of lava
2) Cinder cone volcano: tall and narrow and has steep slopes made mostly of ash
3) Composite volcano: wide and has fairly steep slopes made of lava and ash

Ring of Fire: area on the Pacific Plate boundaries where many of the world’s volcanoes are located
and many earthquakes occur (page C17)

Volcanoes may be classified according to eruption activity:
1) Active: the volcano is currently erupting or has recently erupted
2) Dormant: the volcano has not erupted in some time
3) Extinct: the volcano has stopped erupting

An earthquake is a shaking of the ground due to a sudden release of energy in Earth’s crust.
Earthquakes occur at plate boundaries or along faults in the crust. A fault is a break or a place
where Earth’s crust moves.

Earthquakes are measured with an instrument called a seismograph. The seismograph measures
seismic waves that travel within the Earth. The center of an earthquake below Earth’s surface is
called a focus. The exact location on the Earth’s surface directly above the focus is called the
epicenter.