California Geology midterm Exam
Questions and Answers 100% PASS
What are the different kinds of plate boundaries? what is the relative motion of
each boundary? - CORRECT ANSWER-3 types:
1. subduction (conversion) -plates crash into each other
2. Transform plate boundary- plates slide past each other
3. Divergent plate boundary- plates move away from each other (mid ocean ridges)
How is the global pattern of earthquake and volcano locations related to plate
tectonics? - CORRECT ANSWER-Plates define earthquakes and volcanoes.
Mainly subduction plate zones
Describe the layered structure of the earth (crust-mantle-core). What is each layer
composed of? About how thick is each layer? - CORRECT ANSWER-Layered
structure: Mantle and core. The core is composed of inner solid mostly iron core
and outer liquid core. The Mantle is iron, magnesium, and silicates. The mantle
contains lower mantle (thickest) , Asthenosphere (less thick), and Lithosphere
(Thinnest).
,What defines the "plate" in plate tectonics? How thick is an ocean plate? -
CORRECT ANSWER-Lithosphere= crust and rigid upper mantle BRITTLE.
move relative to each other. An ocean plate is 5 miles in thickness, much thinner
than continental plates.
What are the differences between continental and oceanic crust? - CORRECT
ANSWER-continental-formed from convergent plate boundaries, felsic +
transitional rocks
oceanic- formed from divergent plate bondaries, mafic rocks
How old is the oldest ocean crust and how does that compare with theage of the
continental crust? - CORRECT ANSWER-ocean crust is consantly re forming,
around 200 myo
continental crust takes a long time to form rarely destroyed- 1 - 4 billion yo
What is the difference between the crust of the earth and thelithosphere? -
CORRECT ANSWER-Lithosphere is uppermost mantle, and brittle. Crust is part
of lithosphere
What is the nature of the change across the crust-mantle boundary and the
lithosphere-asthenosphere boundary? (mineralogy/chemistry change versus
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, mechanical change...) - CORRECT ANSWER-the transition from lithosphere to
crust is chemical
the transition from asthenosphere to lithosphere is flowing magma to brittle
What causes the plates to move? - CORRECT ANSWER-convection currents in
the mantle
What are typical rates of plate motions? - CORRECT ANSWER-1-10 cm per year
How do we know these rates? - CORRECT ANSWER-gps- relative and absolute
plate velocity
Why does the oceanic lithosphere subduct? - CORRECT ANSWER-its overall
density is greater than the underlying mantle
What kind of plate boundaries are in CA and where are they? - CORRECT
ANSWER-1. convergent plate boundaries- cascades
2. Divergent- salton sea
3. Transform- san andreas fault
When did the San Andreas fault system begin in CA and what kind of plate motion
did the San Andreas fault replace? - CORRECT ANSWER-15-20 mya. The san
andreas fault replaced divergent plate boundaries.
What Plate is Santa Cruz located on? - CORRECT ANSWER-san andreas fault
Questions and Answers 100% PASS
What are the different kinds of plate boundaries? what is the relative motion of
each boundary? - CORRECT ANSWER-3 types:
1. subduction (conversion) -plates crash into each other
2. Transform plate boundary- plates slide past each other
3. Divergent plate boundary- plates move away from each other (mid ocean ridges)
How is the global pattern of earthquake and volcano locations related to plate
tectonics? - CORRECT ANSWER-Plates define earthquakes and volcanoes.
Mainly subduction plate zones
Describe the layered structure of the earth (crust-mantle-core). What is each layer
composed of? About how thick is each layer? - CORRECT ANSWER-Layered
structure: Mantle and core. The core is composed of inner solid mostly iron core
and outer liquid core. The Mantle is iron, magnesium, and silicates. The mantle
contains lower mantle (thickest) , Asthenosphere (less thick), and Lithosphere
(Thinnest).
,What defines the "plate" in plate tectonics? How thick is an ocean plate? -
CORRECT ANSWER-Lithosphere= crust and rigid upper mantle BRITTLE.
move relative to each other. An ocean plate is 5 miles in thickness, much thinner
than continental plates.
What are the differences between continental and oceanic crust? - CORRECT
ANSWER-continental-formed from convergent plate boundaries, felsic +
transitional rocks
oceanic- formed from divergent plate bondaries, mafic rocks
How old is the oldest ocean crust and how does that compare with theage of the
continental crust? - CORRECT ANSWER-ocean crust is consantly re forming,
around 200 myo
continental crust takes a long time to form rarely destroyed- 1 - 4 billion yo
What is the difference between the crust of the earth and thelithosphere? -
CORRECT ANSWER-Lithosphere is uppermost mantle, and brittle. Crust is part
of lithosphere
What is the nature of the change across the crust-mantle boundary and the
lithosphere-asthenosphere boundary? (mineralogy/chemistry change versus
COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED
, mechanical change...) - CORRECT ANSWER-the transition from lithosphere to
crust is chemical
the transition from asthenosphere to lithosphere is flowing magma to brittle
What causes the plates to move? - CORRECT ANSWER-convection currents in
the mantle
What are typical rates of plate motions? - CORRECT ANSWER-1-10 cm per year
How do we know these rates? - CORRECT ANSWER-gps- relative and absolute
plate velocity
Why does the oceanic lithosphere subduct? - CORRECT ANSWER-its overall
density is greater than the underlying mantle
What kind of plate boundaries are in CA and where are they? - CORRECT
ANSWER-1. convergent plate boundaries- cascades
2. Divergent- salton sea
3. Transform- san andreas fault
When did the San Andreas fault system begin in CA and what kind of plate motion
did the San Andreas fault replace? - CORRECT ANSWER-15-20 mya. The san
andreas fault replaced divergent plate boundaries.
What Plate is Santa Cruz located on? - CORRECT ANSWER-san andreas fault
