GHERIANY INTERNATIONAL SCHOOLS
SCIENCE DEPARTMENT
Shaping earths surface
• Plate tectonics is a scientific theory that explains how landforms are created
from the movement of the Earth.
• The earth's crust is broken into Seven large plates and into several smaller
plates.
1. Convergent
• Converge = to come together
• Convergent boundaries occur when plates move towards one another.
2. Divergent
• Diverge = move away or extend in different directions
• Divergent boundaries occur when two tectonic plates move away from each
other.
3. Transform
• Transform = to change
• Transform boundaries grind past each other without going up or down.
How Mountains are Made
There are 5 main types of mountains:
Each one is formed differently.
1. Fold Mountains
• Fold mountains occur when tectonic plates collide.
• The edges of the plates crumple as they are pushed together
• Around 55 million years ago, two large landmasses, India and Eurasia, collided
with each other, resulting in the Himalayas. This is called continental-
continental convergence.
2. Fault-block Mountains
• large chucks of rock can be pushed up while others are pushed down.
• This creates mountains with a long slope on one side, and a sharp drop on the
other.
• The Sierra Nevada mountains in California, USA are fault-block mountains.
• Weathering and erosion are geological processes that contribute to the
breakdown and transformation of rocks and landforms.
Volcanoes
• Volcanoes are openings in the Earth's crust through which molten rock, gas,
and other materials are released from deep within the Earth.
• Volcanoes are formed when molten rock called magma rises to the surface.
The magma can come from the Earth's mantle or from subduction zones
where one tectonic plate slides beneath another.
• Volcanoes both build and destroy landscapes. Eruptions of lava, ash, volcanic
bombs and blocks form new land on oceanic islands.
• Volcanic eruptions are also destructive as they can blow apart those very
same mountains.
➢ When scientists mapped the location of all the known volcanoes
on Earth, they found a pattern.
➢ Most volcanoes are located where Earth’s plates meet. Remember that
Earth’s crust is made up of large plates. Where these plates meet, they
sometimes push over or under each other. This leads to both earthquakes and
volcanic activity.
➢ Earth’s largest plate is known as the Pacific plate. It sits beneath the
Pacific Ocean. All around the Pacific plate, where it meets other plates,
are many volcanoes.
• There are so many volcanoes that the pattern they form is called the Ring of
Fire.
• There are around 500 active volcanoes in the world. Over 450 of these can be
found along the Ring of Fire. Krakatau was one volcano along the Ring of Fire.
How is a volcano formed?
➢ Near a chain of volcanic islands in the Pacific Ocean, the ocean boils and
froths.
➢ Gases explode into the air, along with fragments of lava that have been
cooled and hardened by contact with the air and seawater.
➢ This is the birth of a volcano. For several days, the volcano erupts at the
surface of the sea, forming an island of solid igneous rock.
➢ One week later the eruption has stopped. As time passes, organisms
eventually settle on the island, and over decades, a forest grows. Then,
seemingly out of nowhere, the volcano erupts again.
• Mauna Loa, a volcano on Big Island, Hawaii, has erupted 33 times since 1843.
These eruptions are constantly changing the landscape of the island.
• A plume of magma can form in one spot
under Earth’s crust if enough heat and
material in Earth’s mantle happens to be rising
there.
• Geologists call this a hot spot. The plume pierces Earth’s crust
and produces a volcano on the surface. As the plate moves over time
but the plume does not, the volcanic activity produces a chain of volcanoes. This is
how the Hawaiian Islands and the seamounts near the islands
formed.
• The volcanoes to the
northwest of the hot spot are
older and more weathered
and eroded. The younger
volcanoes, including those on
Big Island, are less weathered
and larger.
Earthquake
An earthquake is a sudden and violent shaking of the ground, often caused by the
movement of tectonic plates beneath the Earth's surface. It is a natural geological
phenomenon that results from the release of energy in the Earth's crust, leading to
seismic waves that propagate through the Earth.
• How an earthquake affects Earth’s surface depends on:
1. The size of the seismic waves
2. what the ground is made of
3. what is on the surface
➢ In some places, the ground can be made up of
loose or water-saturated soil. When seismic waves pass through it during an
earthquake, anything that is in or on top of soil could sink or topple over.
➢ Firmer ground shakes less, but it can move up or down relative to its original
position. This can cause a lot of damage to any structures built over that area
Earthquakes can change the shape of the earth by forming:
1. Fault zone
2. Landslide
3. Tsunami
Tsunami
➢ A wave or series of waves produced by a large
displacement of water. This means water was
forced out of place. Displacement can be
caused by the seafloor lifting up or dropping
down. Earthquakes can cause tsunamis, too.
Impact craters
They are geological features formed when celestial objects, such as meteoroids,
asteroids, or comets, collide with the surface of a planet, moon, or other solid body
in space. The process of creating an impact crater involves the release of an great
amount of energy upon impact, leading to the excavation and modification of the
surface.
