GLG 103 Lab 7:Mapping Painted Canyon |
2026/2027 Updated | 100% Correct - Arizona
State University.
Practice Question Bank & Answer Rationale
THIS PACK CONTAINS
50 exam-style multiple-choice questions. Each question includes the correct answer and a complete rationale
for focused revision.
COVERAGE
This lab exam assesses mastery of geologic mapping principles applied to the Painted Canyon field area,
including topographic map reading, contact and structural data interpretation, stratigraphic column
construction, and cross-section synthesis using 2026-2027 GSA and National Geologic Mapping Act
standards.
STUDY GUIDE
Recommended duration: 2 hours 50 minutes. Passing target: 70% (35/50).
HIGHP - Page 1 of 19
,1. On the Painted Canyon map, a distinctive sandstone bed is exposed at three points: (1)
at the bottom of a vertical cliff, (2) at the top of the same cliff, and (3) at the same elevation
on the opposite canyon wall. The map shows a V-shaped outcrop pattern pointing
upstream. What is the most likely structural interpretation?
[ ] A. The bed is horizontal and the V-pattern is due to topography alone.
[ ] B. The bed dips upstream at an angle greater than the stream gradient.
[ ] C. The bed is vertical and the V-pattern reflects a fault.
[ ] D. The bed dips downstream and the V-pattern is a topographic artifact.
CORRECT: B. The bed dips upstream at an angle greater than the stream gradient.
A V-shaped outcrop pointing upstream in a valley indicates the bed dips upstream (into the hill) at an angle
greater than the valley gradient; if it were horizontal, the outcrop would parallel contours. Vertical beds would
produce straight outcrop lines independent of topography. Downstream-dipping beds produce V-shapes
pointing downstream.
2. A geologist measures a stratigraphic section in Painted Canyon: a limestone unit is 120
m thick and strikes N30°E, dipping 25°SE. A vertical drill hole intersects the limestone at a
depth of 80 m. What is the true vertical thickness of the limestone?
[ ] A. 120 m
[ ] B. 80 m
[ ] C. 109 m
[ ] D. 132 m
CORRECT: C. 109 m
True vertical thickness (TVT) = true stratigraphic thickness × cos(dip). Here, 120 m × cos(25°) 120 × 0.9063
108.8 m, which rounds to 109 m. The drill hole depth (80 m) is irrelevant to TVT unless the hole is inclined;
the question asks for vertical thickness, not depth.
3. A geologic map of Painted Canyon shows a series of parallel, evenly spaced outcrop
belts of alternating sandstone and shale. The contacts are straight and parallel to the
regional strike. Which structural setting is most consistent with this map pattern?
[ ] A. A gently plunging anticline
[ ] B. A homocline dipping uniformly
[ ] C. A dome with radial dips
[ ] D. A basin with inward dips
CORRECT: B. A homocline dipping uniformly
Parallel, evenly spaced outcrop belts with straight contacts indicate a homocline (uniform dip in one direction)
where topography intersects dipping strata. Anticlines, domes, and basins produce curved or V-shaped
outcrop patterns due to folding.
HIGHP - Page 2 of 19
, 4. Using the principle of faunal succession, a geologist correlates a fossil-rich limestone
in Painted Canyon with a similar limestone 50 km away. The index fossil is a trilobite
species known to range from the Middle Cambrian to Early Ordovician. Which conclusion
is most robust?
[ ] A. The two limestones are exactly the same age.
[ ] B. The two limestones are both Cambrian or Ordovician in age.
[ ] C. The two limestones were deposited in identical environments.
[ ] D. The two limestones are separated by an unconformity.
CORRECT: B. The two limestones are both Cambrian or Ordovician in age.
Index fossils constrain age ranges, not exact ages. The trilobite's range indicates both limestones fall within
the Middle Cambrian to Early Ordovician interval. Lithologic similarity does not guarantee identical
depositional environments or exact time equivalence.
5. A cross-section across Painted Canyon shows a fault that cuts a 10 Ma volcanic ash
layer but is overlain by a 5 Ma lava flow. Which statement best describes the fault's age?
[ ] A. The fault is older than 10 Ma.
[ ] B. The fault is younger than 5 Ma.
[ ] C. The fault is between 10 Ma and 5 Ma old.
[ ] D. The fault is exactly 7.5 Ma old.
CORRECT: C. The fault is between 10 Ma and 5 Ma old.
The fault cuts the 10 Ma ash (so it is younger than 10 Ma) and is overlain by the 5 Ma lava (so it is older than
5 Ma). Therefore, the fault formed between 10 and 5 Ma. The exact age cannot be determined without
additional data.
6. On a topographic map of Painted Canyon, the contour interval is 20 m. A stream flows
from a point at elevation 600 m to a point at elevation 400 m over a horizontal distance of 2
km. What is the average gradient of the stream?
[ ] A. 0.01 (1%)
[ ] B. 0.10 (10%)
[ ] C. 0.20 (20%)
[ ] D. 0.05 (5%)
CORRECT: B. 0.10 (10%)
Gradient = (elevation change) / (horizontal distance) = (600 400) m / 2000 m = 200/2000 = 0.10, or 10%.
The contour interval is irrelevant for this calculation.
HIGHP - Page 3 of 19
2026/2027 Updated | 100% Correct - Arizona
State University.
Practice Question Bank & Answer Rationale
THIS PACK CONTAINS
50 exam-style multiple-choice questions. Each question includes the correct answer and a complete rationale
for focused revision.
COVERAGE
This lab exam assesses mastery of geologic mapping principles applied to the Painted Canyon field area,
including topographic map reading, contact and structural data interpretation, stratigraphic column
construction, and cross-section synthesis using 2026-2027 GSA and National Geologic Mapping Act
standards.
STUDY GUIDE
Recommended duration: 2 hours 50 minutes. Passing target: 70% (35/50).
HIGHP - Page 1 of 19
,1. On the Painted Canyon map, a distinctive sandstone bed is exposed at three points: (1)
at the bottom of a vertical cliff, (2) at the top of the same cliff, and (3) at the same elevation
on the opposite canyon wall. The map shows a V-shaped outcrop pattern pointing
upstream. What is the most likely structural interpretation?
[ ] A. The bed is horizontal and the V-pattern is due to topography alone.
[ ] B. The bed dips upstream at an angle greater than the stream gradient.
[ ] C. The bed is vertical and the V-pattern reflects a fault.
[ ] D. The bed dips downstream and the V-pattern is a topographic artifact.
CORRECT: B. The bed dips upstream at an angle greater than the stream gradient.
A V-shaped outcrop pointing upstream in a valley indicates the bed dips upstream (into the hill) at an angle
greater than the valley gradient; if it were horizontal, the outcrop would parallel contours. Vertical beds would
produce straight outcrop lines independent of topography. Downstream-dipping beds produce V-shapes
pointing downstream.
2. A geologist measures a stratigraphic section in Painted Canyon: a limestone unit is 120
m thick and strikes N30°E, dipping 25°SE. A vertical drill hole intersects the limestone at a
depth of 80 m. What is the true vertical thickness of the limestone?
[ ] A. 120 m
[ ] B. 80 m
[ ] C. 109 m
[ ] D. 132 m
CORRECT: C. 109 m
True vertical thickness (TVT) = true stratigraphic thickness × cos(dip). Here, 120 m × cos(25°) 120 × 0.9063
108.8 m, which rounds to 109 m. The drill hole depth (80 m) is irrelevant to TVT unless the hole is inclined;
the question asks for vertical thickness, not depth.
3. A geologic map of Painted Canyon shows a series of parallel, evenly spaced outcrop
belts of alternating sandstone and shale. The contacts are straight and parallel to the
regional strike. Which structural setting is most consistent with this map pattern?
[ ] A. A gently plunging anticline
[ ] B. A homocline dipping uniformly
[ ] C. A dome with radial dips
[ ] D. A basin with inward dips
CORRECT: B. A homocline dipping uniformly
Parallel, evenly spaced outcrop belts with straight contacts indicate a homocline (uniform dip in one direction)
where topography intersects dipping strata. Anticlines, domes, and basins produce curved or V-shaped
outcrop patterns due to folding.
HIGHP - Page 2 of 19
, 4. Using the principle of faunal succession, a geologist correlates a fossil-rich limestone
in Painted Canyon with a similar limestone 50 km away. The index fossil is a trilobite
species known to range from the Middle Cambrian to Early Ordovician. Which conclusion
is most robust?
[ ] A. The two limestones are exactly the same age.
[ ] B. The two limestones are both Cambrian or Ordovician in age.
[ ] C. The two limestones were deposited in identical environments.
[ ] D. The two limestones are separated by an unconformity.
CORRECT: B. The two limestones are both Cambrian or Ordovician in age.
Index fossils constrain age ranges, not exact ages. The trilobite's range indicates both limestones fall within
the Middle Cambrian to Early Ordovician interval. Lithologic similarity does not guarantee identical
depositional environments or exact time equivalence.
5. A cross-section across Painted Canyon shows a fault that cuts a 10 Ma volcanic ash
layer but is overlain by a 5 Ma lava flow. Which statement best describes the fault's age?
[ ] A. The fault is older than 10 Ma.
[ ] B. The fault is younger than 5 Ma.
[ ] C. The fault is between 10 Ma and 5 Ma old.
[ ] D. The fault is exactly 7.5 Ma old.
CORRECT: C. The fault is between 10 Ma and 5 Ma old.
The fault cuts the 10 Ma ash (so it is younger than 10 Ma) and is overlain by the 5 Ma lava (so it is older than
5 Ma). Therefore, the fault formed between 10 and 5 Ma. The exact age cannot be determined without
additional data.
6. On a topographic map of Painted Canyon, the contour interval is 20 m. A stream flows
from a point at elevation 600 m to a point at elevation 400 m over a horizontal distance of 2
km. What is the average gradient of the stream?
[ ] A. 0.01 (1%)
[ ] B. 0.10 (10%)
[ ] C. 0.20 (20%)
[ ] D. 0.05 (5%)
CORRECT: B. 0.10 (10%)
Gradient = (elevation change) / (horizontal distance) = (600 400) m / 2000 m = 200/2000 = 0.10, or 10%.
The contour interval is irrelevant for this calculation.
HIGHP - Page 3 of 19
