III. Question (51-75) Flashcards
Ratio of open space to total volume
Porosity
Gravity-induced downslope movement of rocks and soil
Mass wasting
Intersection of land and water table, where groundwater seeps out
Spring
Cone shaped calcite deposits growing up from the cave floor
Stalagmite
A vent from which volcanic gases and water vapor escape
Fumarole
Cone shaped calcite deposits growing up from the cave floor
Stalagmite
Slope of the water table
Hydraulic gradient
Movement of loose rock and soil as a viscous fluid mass
Crater
Sinking of earth surface due to compaction or dissolution of subsurface materials
Subsidence
Rock that forms karst topography
Limestone
What kind of fold is depicted in the following figure on the right?
a. Homocline
b. Monocline
c. Unicline
d. Recumbent
Monocline
is a symbol for
a) vertical bed
b) vertical fault
c) overturned fold
d) horizontal fold
e) dome
e) dome
On the diagram above, where would phyllite form?
a) 18,
b) 22,
c) 14,
d) 15,
e) phyllite is not on this diagram.
On the diagram above, where would shale form?
a) 22,
b) shale is not on this diagram,
c) 14,
d) 16,
e) 20
On the diagram above, the region of high pressure and high temperature is
a) 20,
b) 22,
c) 16,
d) 14,
e) 16
On the diagram above, the metamorphic grade increases from
a) 20 to 14,
b) 14 to 22,
c) 16 to 14,
d) all of these,
e) metamorphic grade is not represented on this diagram.
On the diagram above, the trajectory representing burial metamorphism is
a) 14 to 20,
b) 14 to 22,
c) 14 to 16,
d) 20 to 22,
e) 15 to 21.
On the diagram above, the trajectory representing tectonic metamorphism is
a) 14 to 20,
b) 14 to 22,
c) 14 to 16,
d) 20 to 22,
e) 15 to 21.
On the diagram above, the trajectory representing contact metamorphism is
a) 14 to 20,
b) 14 to 22,
c) 14 to 16,
d) 20 to 22,
e) 15 to 21.
Where would phyllite form?
Answer: a) 18
Phyllite forms under intermediate-grade metamorphic conditions, which corresponds to moderate pressure and temperature.
Where would shale form?
Answer: e) 20
Shale forms under low-grade metamorphic conditions, typically at low pressure and low temperature.
The region of high pressure and high temperature is:
Answer: b) 22
This position on the diagram represents the highest pressure and temperature conditions.
The metamorphic grade increases from:
Answer: b) 14 to 22
Metamorphic grade increases with both increasing temperature and pressure.
The trajectory representing burial metamorphism is:
Answer: a) 14 to 20
Burial metamorphism primarily involves an increase in pressure with relatively low temperature increase.
The trajectory representing tectonic metamorphism is:
Answer: a) 14 to 20
Tectonic metamorphism is characterized by increasing pressure, typically related to orogenic (mountain-building) processes.
The trajectory representing contact metamorphism is:
Answer: c) 14 to 16
Contact metamorphism occurs due to a rapid increase in temperature while pressure remains relatively low.
On the diagram, what are the pressure and temperature conditions in the section labeled 15?
a) low pressure, low temperature,
b) high pressure, high temperature,
c) low pressure, high temperature,
d) high pressure, low temperature,
e) none of these.
On the diagram at left, in which fields would you expect to find gneiss?
a) 14,
b) 15 and 17,
c) 16, 18, 20,
d) 19,21,22,
e) 22 only
On the diagram at left, which region is one of intermediate pressure and low temperature?
a) 17,
b) 19,
c) 15,
d) 21,
e) 22
On the diagram, what are the pressure and temperature conditions in the section labeled 15?
Answer: c) low pressure, high temperature
Section 15 is located toward the right side of the diagram, where temperature is increasing, but pressure remains relatively low.
On the diagram, in which fields would you expect to find gneiss?
Answer: d) 19, 21, 22
Gneiss forms under high-grade metamorphic conditions, which correspond to high pressure and high temperature.
On the diagram, which region is one of intermediate pressure and low temperature?
Answer: a) 17
Region 17 represents intermediate pressure with relatively low temperature conditions.
Pangea broke up into two subcontinents. One was called .
a. India b. Asia c. Laura d. Laurasia e. Gondwa
d. Laurasia
Three wells are drilled on a flat surface at elevation 200 masl. They intersect the contact between a shale overlying a sandstone with the following readings:
Location Elevation of contact of shale and conglomerate above sea level
A. Reference point 180 m
B. 70 m N50°W of A 140 m
C. 200 m N10°E of A 0 m
What is the apparent dip of the shale-sandstone contact on a vertical cross section striking E-W?
a. 31°
b. 21°
c. cannot be determined°
d. 40°
e. 12°
d. 40°
The true strike and dip of a limestone bed is N45°E and 30°NW respectively. The apparent dip of the bed on a cross section trending N80°W is ____ .
a. 15°
b. 25°
c. 35°
d. 45°
e. nota
a. 15°
Apparent dips of a sandstone unit measured on two vertical quarry faces are 20° N10°E and 15° N85°W. The true dip and strike of the sandstone unit are ____ .
a. N52°E, 25°NW
b. N25°E, 52°NW
c. N52°W, 25°NE
d. N25°W, 52°NE
e. nota
a. N52°E, 25°NW
The __ axis bisects shear joints
a. σ₁
b. σ₂
c. σ₃
d. σ₁ and σ₂
e. nota
a. σ₁
Explanation:
In structural geology, shear joints commonly form at an angle to the maximum principal stress axis (σ₁). The σ₁ axis typically bisects the acute angle between conjugate shear joints or fractures, indicating the direction of maximum compressive stress.
The symbol “⊥” is symbol for
a) vertical bed
b) vertical fault
c) overturned fold
d) horizontal fold
e) dome
a) vertical bed
Explanation:
The symbol shown (⊥) represents a vertical bed in geological maps and cross-sections. It indicates that the bedding plane is oriented vertically, with no apparent dip angle.
In a classical strike-slip fault, the fault plane is .
a. vertical b. oblique c. to the left d. horizontal e. to the right
a) vertical
Explanation:
In a classical strike-slip fault, the fault plane is typically vertical or near-vertical. Movement along the fault is predominantly horizontal, with lateral displacement to the left (left-lateral) or right (right-lateral), but the fault plane itself remains vertical.
One limb of a fold strikes N35°W and dips 45°NE. The other limb strikes N10°E and dips 60°NW. The plunge (dip angle and direction) of the fold axis is .
a. 26° 86°E b. 6°S26°E c. 6° N25°W d. 26° N6°W e. nota
c) 6° N25°W
The plane of unloading joints is _________ to σ₁ .
a. diagonal b. parallel c. in same plane d. perpendicular a. note
d) perpendicular
Explanation:
Unloading joints (also known as exfoliation joints) form as a result of the release of confining pressure (usually σ₁). They develop perpendicular to the maximum compressive stress (σ₁), as the rock expands and fractures when pressure is reduced.
A magnitude 7 (Mw) earthquake is produced by a north-south trending segment of the Manila Trench. Its epicenter is located 50 km east of the trench axis. Its focus is computed to be 50 km deep. Its focal mechanism solution reveals that the earthquake was produced by either of two thrust faults. One fault strikes N20°E, dips 45°SE; the other strikes in the same direction as the first, but dips 30°NW. Assume pitch for both faults to be 90°. The dip (angle + direction) of the Benioff Zone is ________.
a) 60°
b) 45°
c) 15°
d) Can’t be determined
e) nota
a) 60°
The other was called ______.
a) Europe
b) Gondwana
c) Laura
d) Laurasia
e) Gondwa
b) Gondwana
