“Building” Features on Earth’s Surface
Plate tectonics
Tectonics comes from the
Greek word tekton which
means builder.
Plate tectonics refers to
the building of features
on Earth’s surface due to
deformation caused by
plate movements.
“Building” Features on Earth’s Surface
Plate movements create
mountain ranges, trenches
and rift valleys at or near
plate boundaries.
There is a relationship
between volcanoes and
plate boundaries, and
earthquakes and plate
boundaries.
“Building” Features on Earth’s Surface
•Oceanic trenches are created when one plate goes under
another (subduction.)
•The valley above the subduction zone is called a “trench”
“Building” Features on Earth’s Surface
Trenches can be over 10,000
meters deep.
•They are common in the western
Pacific where there is ocean-
ocean subduction.
•A long trench is located along the
west coast of South America,
where the Nazca Plate is being
subducted under the continent.
“Building” Features on Earth’s Surface
Volcanoes at Plate Boundaries
Volcanoes are
common along mid-
ocean ridges and
subduction zones,
where they form
volcanic arcs (volcanic
islands)
“Building” Features on Earth’s Surface
Volcanoes at Plate Boundaries
Magma is produced above
the subducted plate and
rises toward the surface.
Magma rises because it is
less dense than the
surrounding rock.
“Building” Features on Earth’s Surface
Volcanoes at Plate Boundaries
The “Ring of Fire” around the Pacific Ocean is caused by this
melting at subduction zones.
“Building” Features on Earth’s Surface
Volcanoes at Plate Boundaries
“Building” Features on Earth’s Surface
Hot Spots
“Hot spots” begin at the
boundary between the mantle
and outer core.
These are narrow columns of
hot mantle material.
They rise to the surface,
creating hot spot volcanoes.
“Building” Features on Earth’s Surface
Hot Spots
“Building” Features on Earth’s Surface
Hot Spots
Some hot spots are located under continents.
-The Rift Valley in Africa
“Building” Features on Earth’s Surface
Hot Spots
Some hot spots are located under continents.
-Yellowstone National Park
“Building” Features on Earth’s Surface
Hot Spots
“Building” Features on Earth’s Surface
Mountains at Plate Boundaries
Large mountain ranges are often located near convergent plate
boundaries.
“Building” Features on Earth’s Surface
Mountains at Plate Boundaries
Himalayas between India and China
Alps in Europe
Andes in South America
Coastal mountain ranges in the western United States
“Building” Features on Earth’s Surface
Mountains at Plate Boundaries
Mountains are built in two ways.
1. Magma forms chains of
volcanoes which are mountains.
2. When two plates are pushed
together and stacked on top of
each other.
“Building” Features on Earth’s Surface
Growth of Continents at Subduction Zones
“Building” Features on Earth’s Surface
Growth of Continents at Subduction Zones
Continental accretion:
When two plates meet and one is subducted
(goes under the other,) layers of sediment are
scraped off the plate that goes under.
The material (layers of sediment) is turned into
rock by heat and pressure.
The material makes the continent grow larger.
“Building” Features on Earth’s Surface
Growth of Continents
Continents also grow because of volcanoes and batholiths.
“Building” Features on Earth’s Surface
Earthquakes and Plate Tectonics
Plates moving past each other do not
always slide smoothly.
Transform faults that are on land or
close to land can be dangerous to
people.
Ex. San Andreas Fault
“Building” Features on Earth’s Surface
Earthquakes and Plate Tectonics
“Building” Features on Earth’s Surface
Earthquakes and Plate Tectonics
“Building” Features on Earth’s Surface
Earthquakes and Plate Tectonics
Earthquakes at subduction
zones and continent-
continent collision zones
are also dangerous for
people.
The Pacific Rim is an
example.
Another area stretches
from the Mediterranean to
southeast Asia.
“Building” Features on Earth’s Surface
Earthquakes and Plate Tectonics
Earthquakes in subduction zones can be shallow, near the
trench, up to as deep as hundreds of kilometers.
Earthquakes near continent-continent collision zones can effect
large areas as one continent is pushed under the other.
“Building” Features on Earth’s Surface
Earthquakes and Plate Tectonics
“Building” Features on Earth’s Surface
Earthquakes, Tsunamis, and Plate Tectonics