How do Movements of the Crust
Change Landforms?
Vocabulary:
Earthquake
Epicenter
Fault
Plates
Magma
Lava
Volcano
Earth’s Structure
Earth has four layers. They are the crust, the
mantle, the outer core, and the inner core. The
crust is solid rock. The mantle is made up of solid
and melted rock. The outer core is liquid iron. The
inner core is solid metal.
Earth’s crust and upper mantle are divided
into pieces. Those pieces are called plates. The
plates fit together like a puzzle.
Plates move because they “float” on the
softer rock of the mantle. Moving plates cause
many changes in Earth’s surface.
Earthquakes
An earthquake happens when there is a
sudden release of energy of Earth’s crust. That
causes the ground to shake.
The place in the crust where the energy is
released is called the focus. The epicenter is the
point of the Earth’s surface right above the focus.
The worst damage is usually at the epicenter.
Most earthquakes happen along a fault. A
fault is a crack in Earth’s crust. Some faults are in
the middle of a plate. Most are at the edges of
plates.
Volcanoes
Melted, or molten, rock beneath Earth’s surface is known as
magma. Magma may flow through an opening, or vent, in the crust.
When magma reaches Earth’s surface, it is called lava.
As lava flows from a vent, a volcano forms. A volcano made of lava,
ash, or other materials. The materials come from eruptions. An
eruption is anytime lava or other materials out of a vent.
Sometimes there is a very hot column of magma called a hot spot.
As a plate moves above it, the hot spot melts holes in the crust. The
hot spot can form a chain of volcanoes.
How Mountains Form
When plates move, the can create mountains.
Many mountains form where plates come
together. One plate may be pushed up while the
other plate is pushed down. Or both plates may
be pushed up.
Mountains can also form in the middle of a plate.
Surrounding plates sometimes push on the plate
between them. The pushing can cause rock in the
middle of the plate to rise up. Then new
mountains appear.