Geologic Events – Practice Questions
Base your answers to questions 1 through 3 on the geologic cross section below in which overturning has not
occurred. Letters A through H represent rock layers.
1. Which sequence of events most likely
caused the unconformity at the bottom of rock
layer B?
(1) folding uplift erosion deposition
(2) intrusion erosion folding uplift
(3) erosion folding deposition intrusion
(4) deposition- uplift erosion folding
2. The folding of rock layers G through C was most
likely caused by
(1)
(2)
(3)
(4)
erosion of overlying sediments
contact metamorphism
the collision of lithospheric plates
the extrusion of igneous rock
3. Which two letters represent bedrock of the
same age?
(1) A and E
(2) B and D
(3) F and G
(4) D and H
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4. In a certain section of sedimentary rock, fossil
dating shows that younger rock layers are on top of
older layers. This relationship indicates that:
(1) the rock layers were formed according to
the law of superposition
(2) the rock layers were overturned
(3) fossil dating is inaccurate
(4) the sediments that formed the rock layers
were composed of many different minerals
5. An unconformity between two sedimentary
layers is most likely produced by
(1) uplift followed by extensive erosion,
subsidence, and deposition
(2) a period of extrusive volcanism followed
by another period of extrusive volcanism
(3) continuous sedimentation in a deep basin
over a long period
(4) the deposition of gravel followed by the
deposition of sand and silt
6. The diagram below represents an exposed rock
outcrop. Which geologic event occurred last?
(1) intrusion of A
(2) the fault along B
(3) the deposition of gravel at D
(4) the fold at C
7. Unless a series of rock layers has been
overturned, the bottom rock layer usually
(1) is the oldest
(2) contains the greatest variety of minerals
(3) contains fossils
(4) has the finest texture
Based your answers to questions 8 through 12 on the diagram below. The diagram represents a geologic cross
section in which no overturning has occurred.
8. Which feature is represented by line WX?
(1) a former erosional surface
(2) a fault
(3) an area of metamorphism
(4) an igneous intrusion
11. What rock layer is probably the oldest?
(1) D
(2) B
(3) F
(4) A
9. When did the folding of rock layer B most likely
occur?
(1) after the deposition of rock layer D
(2) before the deposition of rock layer A
(3) after the deposition of rock layer C
(4) after the deposition of rock layer E
10. Fossils are least likely to be found in which rock?
(1) E
(2) C
(3) F
(4) D
12. What evidence in the rock layers indicates
that the formation of igneous rock F occurred
after rock layer E was in place?
(1) the zone of contact metamorphism
between rock F and rock E
(2) the unconformity between rock F and
rock layer E
(3) the presence of extrusive igneous rock
below rock layer E
(4) the presence of radioactive minerals in
rock layer F
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13. Decide the order of events for the geologic cross section below.
Deposition of #10-12
YOUNGEST
_________________
_________________
_________________
Deposition of #2-7
OLDEST