California Geology Midterm Exam – Questions
& Answers | Latest Update 2026 | Exam Prep
PDF | Graded A+
What are the different kinds of plate boundaries? what is the relative motion of each
boundary? - correct answer3 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 answerPlates 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 answerLayered 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
answerLithosphere= 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
answercontinental-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 answerocean 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
answerLithosphere 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 mechanical change...)
- correct answerthe 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 answerconvection currents in the mantle
, What are typical rates of plate motions? - correct answer1-10 cm per year
How do we know these rates? - correct answergps- relative and absolute plate velocity
Why does the oceanic lithosphere subduct? - correct answerits overall density is greater
than the underlying mantle
What kind of plate boundaries are in CA and where are they? - correct answer1.
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 answer15-20 mya. The san andreas fault
replaced divergent plate boundaries.
What Plate is Santa Cruz located on? - correct answersan andreas fault
What is the definition of a mineral? - correct answernaturally occurring, inorganic solid
with a specific chemical composition and a definite crystalline structure
What is the difference between a rock and a mineral. - correct answer-mineral is a
chemical comp.
-rock is an aggregate of minerals
Name the important characteristics used to identify minerals. - correct answer1. crystal
form
2. fracture
3. specific gravity
4. cleavage
5. streak
6. hardness
7. luster
How are external physical properties (crystal form, cleavage, hardness,density)
controlled by atomic structure? - correct answerthe atomic structure determines how it
will look etc.
What is the CA state mineral? What is the CA state gem? - correct answermineral- gold
gem- benitoite
rock- serpentinite
What silicate minerals did you see in section or lab (i.e. quartz, feldspar, mica,
amphibole, serpentine) - correct answer-quartz, chert, feldspar, talc, garnet, mica,
olivine, serpentine, amphibole, galena
-non silicates: hematite(oxides) , pyrite (sulfide), magnetite, calcite (carbonate)
& Answers | Latest Update 2026 | Exam Prep
PDF | Graded A+
What are the different kinds of plate boundaries? what is the relative motion of each
boundary? - correct answer3 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 answerPlates 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 answerLayered 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
answerLithosphere= 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
answercontinental-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 answerocean 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
answerLithosphere 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 mechanical change...)
- correct answerthe 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 answerconvection currents in the mantle
, What are typical rates of plate motions? - correct answer1-10 cm per year
How do we know these rates? - correct answergps- relative and absolute plate velocity
Why does the oceanic lithosphere subduct? - correct answerits overall density is greater
than the underlying mantle
What kind of plate boundaries are in CA and where are they? - correct answer1.
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 answer15-20 mya. The san andreas fault
replaced divergent plate boundaries.
What Plate is Santa Cruz located on? - correct answersan andreas fault
What is the definition of a mineral? - correct answernaturally occurring, inorganic solid
with a specific chemical composition and a definite crystalline structure
What is the difference between a rock and a mineral. - correct answer-mineral is a
chemical comp.
-rock is an aggregate of minerals
Name the important characteristics used to identify minerals. - correct answer1. crystal
form
2. fracture
3. specific gravity
4. cleavage
5. streak
6. hardness
7. luster
How are external physical properties (crystal form, cleavage, hardness,density)
controlled by atomic structure? - correct answerthe atomic structure determines how it
will look etc.
What is the CA state mineral? What is the CA state gem? - correct answermineral- gold
gem- benitoite
rock- serpentinite
What silicate minerals did you see in section or lab (i.e. quartz, feldspar, mica,
amphibole, serpentine) - correct answer-quartz, chert, feldspar, talc, garnet, mica,
olivine, serpentine, amphibole, galena
-non silicates: hematite(oxides) , pyrite (sulfide), magnetite, calcite (carbonate)
