Download Chapter 5

PLATE BOUNDARIES AND
CALIFORNIA
Chapter 5
THE BIG IDEA
California is located on a plate boundary, where major
geologic events occur.
Lesson 1: Interactions at Plate Boundaries
 There are three main types of plate boundaries, where stresses cause rocks
to deform.
Lesson 2: California Geology
 Many of California’s landforms were produced by plate tectonic activity,
which continues today.
LESSON 1: INTERACTIONS AT
BOUNDARIES
PLATE
There are three main types of plate boundaries where stresses cause
rocks to deform.
What you’ll learn:
• Describe types of stress that deform rock.
• Relate geologic features of Earth’s surface to types of plate boundaries.
So What?!
Understanding geologic events that occur at plate boundaries can save lives and
prevent damage to property.
REVIEW VOCABULARY
Lithospheric Plate:
Large, brittle pieces of Earth’s outer shell composed
of crust and uppermost mantle.
NEW VOCABULARY
rift valley
Long, narrow valley formed as the hanging wall of a
divergent boundary slips down.
fault
Fracture in which rocks on one side of the fracture
move relative to rocks on the other side.
Divergent P.B.
Transform P.B.
Boundary formed where plates move apart
Boundary formed when two plates move sideways
past each other.
NEW VOCABULARY
fracture
continental rifting
Convergent P.B.
Break or crack in rock
Process that pulls apart a continent.
Boundary formed when two plates move toward each
other.
ACADEMIC VOCABULARY
inclined
Sloping, slanting, or leaning relative to the
horizontal or vertical
The Leaning Tower of Pisa inclines about 3.99
degrees. In other words, the top of the tower
is displaced horizontally 12 ft 10 in from
where it would be if the structure were
perfectly vertical.
DRIFTING CONTINENTS
Types of Rock Stress
Tension
Rocks are pulled
apart; causes
stretching and
thinning of the
lithosphere.
Compression
Shear
Rocks are pushed
together; makes
rock layer thick.
Rocks are pushed in
opposite directions;
neither thickens nor
thins lithosphere
3 MAIN TYPES OF FAULTS
 Normal Fault
 Reverse Fault
 Strike-Slip Fault
SUMMARIZE IT
Rephrase the main ideas of this section in your own
words.
TYPES OF PLATE BOUNDARIES
Sequence the events that occur during continental rifting.
A continent splits apart at a divergent
plate boundary.
Tension stress causes rocks to break and form
normal faults.
The hanging wall slips down and forms a rift
valley.
TYPES OF PLATE BOUNDARIES
Distinguish 3 types of convergent plate boundaries. Describe what happens at each type of
boundary.
Continent-toOcean-to-Continent
Ocean-to-Ocean
Continent
Colder, denser slab is
forced down, forming
a trench; water is
released and melts
rocks, forming
magma.
Denser ocean plate
always sinks below
continental plate;
melting forms a string of
volcanoes along edge of
continent.
Compression forces
force crust to rise,
forming tall
mountains.
TYPES OF PLATE BOUNDARIES
Complete this paragraph about transform plate boundaries.
At transform plate boundaries, plates
Move sideways past each other
______________________________.
In the ocean, these
pieces of mid-ocean ridges
boundaries connect ________________________.
large earthquakes
On the continents, _________________
can occur
along these boundaries.
SUMMARIZE IT!
Summarize three (3) main ideas of the above
sections.
LESSON 2: PLATE BOUNDARIES AND
CALIFORNIA
Many of California’s landforms were produced by plate tectonic
activity, which continues today.
What you’ll learn:
• Describe California’s current plate tectonic setting and how plate movements
have produced landforms.
• Predict future changes in California’s tectonic setting and topography.
So What?!
Interactions between the North American Plate and the Pacific Plate produce
California’s mountains and basins and cause earthquakes and volcanoes.
REVIEW VOCABULARY
uplift
Any process that moves Earth’s surface to a
higher elevation.
NEW VOCABULARY
San Andreas Fault The S.A.F. is a transform boundary (and a
strike-slip fault) between the N.A. Plate
and the Pacific Plate. It extends all the
way from Cape Mendocino in the north to
the Salton Sea in the south.
ACADEMIC VOCABULARY
adjacent
Next to or very near
* The San Andreas Fault is a boundary between two
adjacent plates.
PLATE TECTONICS IN CALIFORNIA
Distinguish two plate boundaries found in California.
1. The San Andreas Fault System, a continental
transform boundary cutting across the state.
2. A convergent plate boundary offshore in the northern
part of the state.
PLATE TECTONICS IN CALIFORNIA
Identify three features of California geology caused by plate tectonics.
1. earthquakes
2. volcanoes
3. mountains
PLATE TECTONICS IN CALIFORNIA
Create a diagram showing the San Andreas Fault.
SUMMARIZE IT!
Summarize the main ideas of the above section of the lesson.
PLATE TECTONICS IN CALIFORNIA
Analyze the role of a convergent plate boundary in shaping CA geology.
The Gorda and Juan de
Fuca plates are forced
beneath the coast.
Melting above the subduction zone
produces the volcanic mountains in
the Cascade Range.
CALIFORNIA’S MOUNTAINS
Organize information about the formation of mountains in California.
I. Subduction
A. Granite rocks formed under volcanic mountains when plates
B.
converged.
An ancient oceanic plate subducted, forming rocks in
several mountain ranges.
II. Rifting
A. Tension stresses cause continental rifting.
B. Panamint Range rises as the crust stretches.
FUTURE PLATE MOVEMENTS
Summarize two changes that might occur in the future as a result of plate tectonics.
 The Pacific Plate will keep moving northwest, bringing Los
Angeles and San Francisco closer.
 Death Valley and the Gulf of California are dropping and
opening up as a result of tension stress.
SUMMARIZE IT!
Rephrase the main ideas of the lesson in your
own words.