ASBOG FG Exam UPDATED
QUESTIONS AND CORRECT ANSWERS
Foot wall and hanging wall - CORRECT ANSWER Foot wall - block that underlies a
non-vertical fault.
Hanging wall - block that overlies a non-vertical fault.
Regressive sequence - CORRECT ANSWER Regression is the withdrawal of the sea
from land. A regressive sequence is represented by limestone overlain by shale overlain by
sandstone.
Order of deposition of evaporites - CORRECT ANSWER Order of deposition:
calcium carbonate - calcite
calcium sulfate - gypsum or anhydrite
sodium chloride - halite
magnesium sulfates and chlorates
sodium bromide and potassium chloride
What are the processes included in diagenesis? - CORRECT ANSWER Compaction,
cementation, reworking, authigenesis, replacement by secondary minerals, crystallization of
secondary minerals, leaching, hydration, bacterial action, formation of concretions.
Bowen's Reaction Series - CORRECT ANSWER Sequence of minerals that form in the
process of fractional crystallization of a magma.
Transgressive sequence - CORRECT ANSWER Transgression is the advance of the sea
onto land. A transgressive sequence is represented by sandstone overlain by shale overlain by
limestone.
What types of geomorphic features are diagnostic of faulting? - CORRECT
ANSWER Sag ponds, offset ridges, fault scarps, triangular facets, aligned springs,
offset streams, scarplets.
,What types of features are indicative of faulting but often are not extensive enough to be
mapped? - CORRECT ANSWER Slickensides, grooving, drag, gouge, mylonite.
What would cause a repetition or omission of units in cross section? - CORRECT
ANSWER Faulting - in general, a reverse fault will cause repetition of beds and normal
faults will cause apparently missing beds.
What should be included on a complete geologic map? - CORRECT ANSWER Scale,
north arrow, geologic symbols, and explanation. The explanation must include all symbols
originally on the map or added (incl. contacts, structure symbols, streams, cross sections) and
a stratigraphic column depicting all units shown on the map and placing them from the oldest
units at the bottom to the youngest at the top. Include lithology, thickness, and names of the
units if available.
What type of V will a vertical bed display on a map? - CORRECT ANSWER A vertical
bed will have no V. A vertical bed crosses all variations of topography with a straight line.
This is also true of any vertical structural feature such as a fault.
Casing - CORRECT ANSWER A heavy metal pipe lowered into a borehole and
cemented in place to prevent cave-in, loss of drilling fluid, and unwanted fluids from entering
the borehole.
Law of Superposition - CORRECT ANSWER The Law of Superposition states that the
oldest layer is on the bottom and the youngest layer is on top, assuming no overturning. If the
beds are overturned or vertical, stratigraphic succession cannot be determined unless absolute
ages of units are known.
How are cross-cutting relationships used to determine relative ages? - CORRECT
ANSWER If cross-cutting relationships exist, the feature that is cut is older than the
feature that cuts across it. Rocks may be cut by intrusion, faulting, unconformities, or
replacement minerals.
Type locality - CORRECT ANSWER Where a geologic feature (such as a fossil
species or geologic formation) was first recognized and describes. Contains the type section.
,Rule of V's - CORRECT ANSWER The outcrop of a formation as it crosses a valley
forms a V shape (as viewed on a map). The V points in the direction that the formation
underlies the valley.
Law of Initial Horizontality - CORRECT ANSWER The sequence of layers was
deposited horizontally or nearly so. The oldest layer is therefore on the bottom and the
youngest layer is on top.
Similarities and differences of reverse faults and normal faults - CORRECT
ANSWER Normal fault: hanging wall has moved down relative to foot wall.
Reverse fault: hanging wall has moved up relative to foot wall.
Both: dip-slip faults with a dip between 45 and 90 degrees.
Unconformity - CORRECT ANSWER A gap in the geologic record, marked by an
interruption in the depositional sequence that implies uplift and erosion have removed part of
the geologic record or that non-deposition has occurred.
Type section - CORRECT ANSWER The originally described stratigraphic unit to
which other parts of the unit elsewhere may be compared. It is preferable to describe the
location where the unit attains its maximum thickness and where the top and bottom of the
unit are exposed.
Tangent equation - CORRECT ANSWER tan(θ) = Opposite / Adjacent
What is the net slip and where is it measured? - CORRECT ANSWER Net slip is the
distance between two formerly adjacent points on either side of a fault, measured on the fault
surface (in the plane of the fault).
Sine equation - CORRECT ANSWER sinθ = opposite/hypotenuse
, Index fossil - CORRECT ANSWER An index fossil identifies and dates the strata in
which it is found. It combines a wide geographic range with a narrow stratigraphic
occurrence.
General form of the thickness equation and why you wouldn't want to use it - CORRECT
ANSWER thickness (t) = outcrop width perpendicular to strike (w) sin[dip(δ),
slope(σ)]
Generally it is easier to solve a thickness problem graphically because you need to draw a
diagram to scale anyway to get the slope angle (σ) and the perpendicular outcrop width (w).
General equation for calculating the apparent dip and when can't you use it - CORRECT
ANSWER tan(α) = tan(δ)sin(β)
α = apparent dip
δ = dip
β = angle between strike and apparent dip direction
This equation can't be used for solving true strike and dip from two apparent dips. For solving
these, you must either solve graphically or using the stereonet.
If an attitude is given as 35°, S25°E, what does that mean? - CORRECT
ANSWER Represents a dip of 35° in the S25°E direction. This translates to a strike of
N65°E and dip of 35°S
If given as an apparent dip value or the bearing and plunge of a line, represents a line
plunging 35° in the direction S25°E. Apparent dip is given in these terms to represent the
apparent dip angle in a given direction.
If you have a flat surface and an outcrop width that is not perpendicular to strike, what
equation would you use to calculate the thickness of the unit? - CORRECT ANSWER t
= lsin(β)sin(δ)
l = traverse distance across the outcrop
β = angle between strike and apparent dip direction
δ = dip
QUESTIONS AND CORRECT ANSWERS
Foot wall and hanging wall - CORRECT ANSWER Foot wall - block that underlies a
non-vertical fault.
Hanging wall - block that overlies a non-vertical fault.
Regressive sequence - CORRECT ANSWER Regression is the withdrawal of the sea
from land. A regressive sequence is represented by limestone overlain by shale overlain by
sandstone.
Order of deposition of evaporites - CORRECT ANSWER Order of deposition:
calcium carbonate - calcite
calcium sulfate - gypsum or anhydrite
sodium chloride - halite
magnesium sulfates and chlorates
sodium bromide and potassium chloride
What are the processes included in diagenesis? - CORRECT ANSWER Compaction,
cementation, reworking, authigenesis, replacement by secondary minerals, crystallization of
secondary minerals, leaching, hydration, bacterial action, formation of concretions.
Bowen's Reaction Series - CORRECT ANSWER Sequence of minerals that form in the
process of fractional crystallization of a magma.
Transgressive sequence - CORRECT ANSWER Transgression is the advance of the sea
onto land. A transgressive sequence is represented by sandstone overlain by shale overlain by
limestone.
What types of geomorphic features are diagnostic of faulting? - CORRECT
ANSWER Sag ponds, offset ridges, fault scarps, triangular facets, aligned springs,
offset streams, scarplets.
,What types of features are indicative of faulting but often are not extensive enough to be
mapped? - CORRECT ANSWER Slickensides, grooving, drag, gouge, mylonite.
What would cause a repetition or omission of units in cross section? - CORRECT
ANSWER Faulting - in general, a reverse fault will cause repetition of beds and normal
faults will cause apparently missing beds.
What should be included on a complete geologic map? - CORRECT ANSWER Scale,
north arrow, geologic symbols, and explanation. The explanation must include all symbols
originally on the map or added (incl. contacts, structure symbols, streams, cross sections) and
a stratigraphic column depicting all units shown on the map and placing them from the oldest
units at the bottom to the youngest at the top. Include lithology, thickness, and names of the
units if available.
What type of V will a vertical bed display on a map? - CORRECT ANSWER A vertical
bed will have no V. A vertical bed crosses all variations of topography with a straight line.
This is also true of any vertical structural feature such as a fault.
Casing - CORRECT ANSWER A heavy metal pipe lowered into a borehole and
cemented in place to prevent cave-in, loss of drilling fluid, and unwanted fluids from entering
the borehole.
Law of Superposition - CORRECT ANSWER The Law of Superposition states that the
oldest layer is on the bottom and the youngest layer is on top, assuming no overturning. If the
beds are overturned or vertical, stratigraphic succession cannot be determined unless absolute
ages of units are known.
How are cross-cutting relationships used to determine relative ages? - CORRECT
ANSWER If cross-cutting relationships exist, the feature that is cut is older than the
feature that cuts across it. Rocks may be cut by intrusion, faulting, unconformities, or
replacement minerals.
Type locality - CORRECT ANSWER Where a geologic feature (such as a fossil
species or geologic formation) was first recognized and describes. Contains the type section.
,Rule of V's - CORRECT ANSWER The outcrop of a formation as it crosses a valley
forms a V shape (as viewed on a map). The V points in the direction that the formation
underlies the valley.
Law of Initial Horizontality - CORRECT ANSWER The sequence of layers was
deposited horizontally or nearly so. The oldest layer is therefore on the bottom and the
youngest layer is on top.
Similarities and differences of reverse faults and normal faults - CORRECT
ANSWER Normal fault: hanging wall has moved down relative to foot wall.
Reverse fault: hanging wall has moved up relative to foot wall.
Both: dip-slip faults with a dip between 45 and 90 degrees.
Unconformity - CORRECT ANSWER A gap in the geologic record, marked by an
interruption in the depositional sequence that implies uplift and erosion have removed part of
the geologic record or that non-deposition has occurred.
Type section - CORRECT ANSWER The originally described stratigraphic unit to
which other parts of the unit elsewhere may be compared. It is preferable to describe the
location where the unit attains its maximum thickness and where the top and bottom of the
unit are exposed.
Tangent equation - CORRECT ANSWER tan(θ) = Opposite / Adjacent
What is the net slip and where is it measured? - CORRECT ANSWER Net slip is the
distance between two formerly adjacent points on either side of a fault, measured on the fault
surface (in the plane of the fault).
Sine equation - CORRECT ANSWER sinθ = opposite/hypotenuse
, Index fossil - CORRECT ANSWER An index fossil identifies and dates the strata in
which it is found. It combines a wide geographic range with a narrow stratigraphic
occurrence.
General form of the thickness equation and why you wouldn't want to use it - CORRECT
ANSWER thickness (t) = outcrop width perpendicular to strike (w) sin[dip(δ),
slope(σ)]
Generally it is easier to solve a thickness problem graphically because you need to draw a
diagram to scale anyway to get the slope angle (σ) and the perpendicular outcrop width (w).
General equation for calculating the apparent dip and when can't you use it - CORRECT
ANSWER tan(α) = tan(δ)sin(β)
α = apparent dip
δ = dip
β = angle between strike and apparent dip direction
This equation can't be used for solving true strike and dip from two apparent dips. For solving
these, you must either solve graphically or using the stereonet.
If an attitude is given as 35°, S25°E, what does that mean? - CORRECT
ANSWER Represents a dip of 35° in the S25°E direction. This translates to a strike of
N65°E and dip of 35°S
If given as an apparent dip value or the bearing and plunge of a line, represents a line
plunging 35° in the direction S25°E. Apparent dip is given in these terms to represent the
apparent dip angle in a given direction.
If you have a flat surface and an outcrop width that is not perpendicular to strike, what
equation would you use to calculate the thickness of the unit? - CORRECT ANSWER t
= lsin(β)sin(δ)
l = traverse distance across the outcrop
β = angle between strike and apparent dip direction
δ = dip
