LAB EXERCISE 10.13 Interpreting Simple Geologic Maps
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Part 1.a. What are the ages above and below the unconformity shown in Map A? -
(correct Answer) - Above: Triassic and Jurassic/Below: Devonian-Silurian
(Q002) Part 2.a. What type of unconformity is present on Map A? - (correct Answer)
- angular unconformity
(Q003) Part 3.a. Describe the angle and direction of dip of the Triassic and
Jurassic strata on Map A. - (correct Answer) - 6 degrees to the north1
(Q004) Part 4.a. Describe the angle and direction of dip of the Silurian and
Devonian strata on Map A. - (correct Answer) - 43 to 56 degrees to the west
(Q005) Part 1.b. Describe the fold present on Map B. Include the type of fold, the
age of the strata in the fold, whether the fold is plunging, and describe the
symmetry of the fold. - (correct Answer) - anticline; Devonian and Silurian; non
plunging; asymmetrical (dip is steeper for one limb than the other)
(Q006) Part 2.b. What type of intrusion is located in the western portion of the
folded layers on Map B? Include age, rock, and type of intrusion. - (correct
Answer) - Cretaceous; granite; pluton
(Q007) Part 3.b. What type of intrusion cuts across both the folded layers and the
intrusion described in the previous question? Include age, rock, and type of
intrusion. - (correct Answer) - Tertiary; basalt; dike
(Q008) Part 1.c. Describe the geologic features of Map C. Include the trend of the
fault and the age and orientation of the strata it cuts across. - (correct Answer)
- Fault is trending about 110; strata has a strike of approximately 025, tilting 12
degrees west
(Q009) Part 2.c. What type of fault is present on Map C and what can you determine
about the relative motion of the rocks on either side of the fault? - (correct
Answer) - Left-lateral strike slip; rocks are moving to the left
(Q010) Part 3.c. What type of unconformity is present on Map C? - (correct Answer)
- disconformity
(Q011) Part 4.c. What are the ages of the rocks above and below the unconformity? -
(correct Answer) - Cretaceous-Devonian
(Q012) Part 1.d. If you walk along the southern edge of Map A, in what direction do
you need to go to walk "up-section" (i.e., into rocks of progressively younger age)
or "down-section" (i.e., into rocks of progressively older age)? - (correct Answer)
- up-section: west/down-section: east
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Part 1.a. What are the ages above and below the unconformity shown in Map A? -
(correct Answer) - Above: Triassic and Jurassic/Below: Devonian-Silurian
(Q002) Part 2.a. What type of unconformity is present on Map A? - (correct Answer)
- angular unconformity
(Q003) Part 3.a. Describe the angle and direction of dip of the Triassic and
Jurassic strata on Map A. - (correct Answer) - 6 degrees to the north1
(Q004) Part 4.a. Describe the angle and direction of dip of the Silurian and
Devonian strata on Map A. - (correct Answer) - 43 to 56 degrees to the west
(Q005) Part 1.b. Describe the fold present on Map B. Include the type of fold, the
age of the strata in the fold, whether the fold is plunging, and describe the
symmetry of the fold. - (correct Answer) - anticline; Devonian and Silurian; non
plunging; asymmetrical (dip is steeper for one limb than the other)
(Q006) Part 2.b. What type of intrusion is located in the western portion of the
folded layers on Map B? Include age, rock, and type of intrusion. - (correct
Answer) - Cretaceous; granite; pluton
(Q007) Part 3.b. What type of intrusion cuts across both the folded layers and the
intrusion described in the previous question? Include age, rock, and type of
intrusion. - (correct Answer) - Tertiary; basalt; dike
(Q008) Part 1.c. Describe the geologic features of Map C. Include the trend of the
fault and the age and orientation of the strata it cuts across. - (correct Answer)
- Fault is trending about 110; strata has a strike of approximately 025, tilting 12
degrees west
(Q009) Part 2.c. What type of fault is present on Map C and what can you determine
about the relative motion of the rocks on either side of the fault? - (correct
Answer) - Left-lateral strike slip; rocks are moving to the left
(Q010) Part 3.c. What type of unconformity is present on Map C? - (correct Answer)
- disconformity
(Q011) Part 4.c. What are the ages of the rocks above and below the unconformity? -
(correct Answer) - Cretaceous-Devonian
(Q012) Part 1.d. If you walk along the southern edge of Map A, in what direction do
you need to go to walk "up-section" (i.e., into rocks of progressively younger age)
or "down-section" (i.e., into rocks of progressively older age)? - (correct Answer)
- up-section: west/down-section: east
