G202 PHYSICAL GEOLOGY MIDTERM
EXAM STUDY GUIDE QUESTIONS AND
ANSWERS 100% VERIFIED. JUST
RELEASED
1. Which of the following describes the mechanism of ‘slab pull’ in plate tectonics?
A. Gravity pushes the elevated ridge crest down and out.
B. Convection currents in the asthenosphere drag the lithosphere along by friction.
C. Mantle plumes push the crust upward creating a radial stress field.
D. Cold, dense subducting lithosphere sinks into the mantle, pulling the rest of the plate.
Answer: D
Conceptual Explanation: Slab pull occurs because old, cold lithosphere is denser than the
underlying asthenosphere, causing it to sink and pull the trailing plate.
2. In Bowen’s Reaction Series, which mineral is the last to crystallize from a cooling silicate
melt?
A. Olivine
B. Biotite
C. Quartz
D. Pyroxene
,Answer: C
Conceptual Explanation: Quartz crystallizes at the lowest temperatures at the end of the
reaction series after most other ions have been depleted.
3. A mineral that breaks along smooth, flat surfaces is said to exhibit:
A. Fracture
B. Conchoidal scarring
C. Hardness
D. Cleavage
Answer: D
Conceptual Explanation: Cleavage is the tendency of a mineral to break along planes of
weak atomic bonding.
4. Which type of magma has the highest silica content and the highest viscosity?
A. Felsic
B. Mafic
C. Intermediate
D. Ultramafic
Answer: A
, Conceptual Explanation: Felsic magmas are rich in silica (SiO2), which leads to the
formation of complex silicate chains that increase viscosity.
5. What is the primary driver of chemical weathering in silicate minerals?
A. Hydrolysis
B. Frost wedging
C. Thermal expansion
D. Abrasion
Answer: A
Conceptual Explanation: Hydrolysis is the reaction between H+ ions and mineral ions,
typically breaking down silicates like feldspar into clay minerals.
6. Which sedimentary structure indicates a paleo-current that periodically reversed direction?
A. Cross-bedding
B. Graded bedding
C. Asymmetric ripple marks
D. Symmetric ripple marks
Answer: D
Conceptual Explanation: Symmetric ripples (oscillation ripples) are formed by the back-
and-forth motion of water, common in shallow marine environments.
EXAM STUDY GUIDE QUESTIONS AND
ANSWERS 100% VERIFIED. JUST
RELEASED
1. Which of the following describes the mechanism of ‘slab pull’ in plate tectonics?
A. Gravity pushes the elevated ridge crest down and out.
B. Convection currents in the asthenosphere drag the lithosphere along by friction.
C. Mantle plumes push the crust upward creating a radial stress field.
D. Cold, dense subducting lithosphere sinks into the mantle, pulling the rest of the plate.
Answer: D
Conceptual Explanation: Slab pull occurs because old, cold lithosphere is denser than the
underlying asthenosphere, causing it to sink and pull the trailing plate.
2. In Bowen’s Reaction Series, which mineral is the last to crystallize from a cooling silicate
melt?
A. Olivine
B. Biotite
C. Quartz
D. Pyroxene
,Answer: C
Conceptual Explanation: Quartz crystallizes at the lowest temperatures at the end of the
reaction series after most other ions have been depleted.
3. A mineral that breaks along smooth, flat surfaces is said to exhibit:
A. Fracture
B. Conchoidal scarring
C. Hardness
D. Cleavage
Answer: D
Conceptual Explanation: Cleavage is the tendency of a mineral to break along planes of
weak atomic bonding.
4. Which type of magma has the highest silica content and the highest viscosity?
A. Felsic
B. Mafic
C. Intermediate
D. Ultramafic
Answer: A
, Conceptual Explanation: Felsic magmas are rich in silica (SiO2), which leads to the
formation of complex silicate chains that increase viscosity.
5. What is the primary driver of chemical weathering in silicate minerals?
A. Hydrolysis
B. Frost wedging
C. Thermal expansion
D. Abrasion
Answer: A
Conceptual Explanation: Hydrolysis is the reaction between H+ ions and mineral ions,
typically breaking down silicates like feldspar into clay minerals.
6. Which sedimentary structure indicates a paleo-current that periodically reversed direction?
A. Cross-bedding
B. Graded bedding
C. Asymmetric ripple marks
D. Symmetric ripple marks
Answer: D
Conceptual Explanation: Symmetric ripples (oscillation ripples) are formed by the back-
and-forth motion of water, common in shallow marine environments.
