8
Analyse
13.
Distinguish
between
geological agents and
processes in the following
list. Then classify them into
external or internal:
glacier
,
sediment transportation
,
risingof amountain chain
,
erosion
,
wind
,
movement
of plates
,
earthquake
,
volcanic eruption
.
2.
EXTERNAL AND INTERNAL GEOLOGICAL
PROCESSES
The Earth’s surface has been subjected to numerous changes and phenomena
known as
geological processes
. Cliff erosion, a volcanic eruption, or sedimentation
at a mouth of a river are examples of these geological processes. The
geological
agents
responsible for these processes are: waves, the internal heat of the Earth,
or rivers.
Geological agents and processes are classified as
internal
and
external
.
❚❚
Internal geological agents and processes
are driven
3
by the heat that is
stored in the Earth’s interior. They usually occur far from the surface. The
main internal geological agent is the movement of the lithospheric plates.
The most evident and catastrophic events caused by this movement are
Earthquakes and volcanic eruptions. Others are the movement of the continents,
the opening of new seas and the closing of old ones, or the formation of
mountain ranges.
It can be said that internal geological processes build the Earth’s relief.
❚❚
External geological agents and processes
affect the Earth’s surface. They are
powered by solar energy. External processes shape the relief created by internal
processes. External agents carry out this process: water, ice, wind, atmosphere
and human beings. They include all the changes that alter or wear down the
rocks and deposit materials resulting from erosion.
Internal agents and processes tend to lift and build the Earth’s relief from the
interior. External agents and processes tend to destroy and shape the Earth’s
relief.
Although processes such as volcanic eruptions and earthquakes affect the Earth’s
surface, they clearly originate in the Earth’s interior. Therefore, they are internal
processes.
external processes
erosion
transport
sedimentation
diagenesis
relief – rocks
internal processes
metamorphosis
magnetism
orogenesis
The action of internal and external geological processes
A geological agent and process
Understand
12.
What process does this
image show? What agent
causes it? Is it internal or
external?
3
drive
(v)
:
to provide the power
for something to work
