tuesday november 2, 2010 (types of plate boundaries)
TRANSCRIPT
TuesdayNovember 2, 2010
(Types of Plate Boundaries)
The Launch PadTuesday, 11/2/10
In 1915, Alfred Wegener first proposed the continental drift hypothesis, which states that a supercontinent called Pangaea began breaking
apart about 200 million years ago. He said that the continents “drifted” to their present positions.List 5 pieces of evidence cited by Wegener that
supported his hypothesis.the fit of South America and Africa
fossils match across the seasrock types and structures match across the
seassimilar mountain ranges on different continentssimilar ancient climates evidence matches
on present-day continents
AnnouncementsIf your need to:
come in and do missing work,
remediate assessments, or
get tutoring,please sign up in the log
book.
We will have a test this Friday.
Assignment Currently Open Pages Date of Notes
on Website Date Issued Date Due
Plate boundaries occur where two crustal plates meet.
There are three types of plate boundaries:
1. Divergent plate boundaries (constructive margins) occur
where two plates move apart.
2. Convergent plate boundaries (destructive
margins) occur where two plates collide.
3. Transform fault boundaries occur where plates slide
past one another
Plate Boundaries
Divergent plate boundaries (constructive margins) occur
where two plates move apart.
The mantle material up-wells to create new seafloor.
Oceanic ridges develop along well-developed boundaries.
Along ridges, seafloor spreading creates new
seafloor.
Divergent Plate Boundaries
Divergent boundaries are located along
oceanic ridges.
Figure 7.11
Distribution of the Oceanic Ridge System
Figure 7.10 (left)
The East African rift is
a divergent
boundary on land
Figure 7.13
Continental rifts form at spreading
centers within a continent.
Figure 7.13 (top right)
Continentalrifting
Convergent plate boundaries
(destructive margins) occur when plates collide, an ocean trench forms, and
lithosphere is subducted into the
mantle.
Convergent Plate Boundaries
Convergent Plate BoundariesOceanic - continental convergence occurs when a denser oceanic slab sinks into the
asthenosphere. Pockets of magma develop and rise and a
continental volcanic arc forms.
An Oceanic - Continental Convergent Plate Boundary
Figure 7.15 A
Convergent Plate BoundariesExamples of oceanic – continental convergence include:the Andes Mountains of South America.
Convergent Plate BoundariesExamples of oceanic – continental convergence include:
the Cascade Mountains of Washington and Oregon.
Convergent Plate BoundariesExamples of oceanic – continental convergence include:
the Sierra Nevada Mountains of California.
Oceanic - oceanic convergence occurs when two oceanic slabs converge and one descends beneath the other. This often forms volcanoes on the ocean floor.
A volcanic island arc forms as volcanoes emerge from the sea.
Convergent Plate Boundaries
Convergent Plate BoundariesExamples of oceanic – oceanic convergence include:
the Aleutian Islands.
Convergent Plate BoundariesExamples of oceanic – oceanic convergence include:
the Mariana Islands.
Convergent Plate BoundariesExamples of oceanic – oceanic convergence include:
the Tonga Islands.
Continental - Continental Convergence When two continental plates converge, they collide.
One continental plate subducts under the other.This can produce buckling of the upper plate and new mountain ranges
form, such as the Himalayas
Convergent Plate Boundaries
The Collision of India and Asia Produced the Himalayas
Transform plates slide past one another.
No new crust is created or destroyed.
Transform faults are created.
Most transform faults join two segments of a mid-
ocean ridge. These faults and ridges aid the movement of
oceanic crustal material.
Transform Plate Boundaries
California’s Fault Issue
GEODe Earth Science
Plate TectonicsSlides 726-754 (P5)