Potential Exam Questions,
Potential Short Answer Questions
- What kind of plate boundary is a(n)
(rift valley, passive margin, intracratonic, foreland,
forearc, trench, ophiolite) tectonic basin associated with?
How do you recognize this tectonic basin (environments and
- Characterize the sedimentary deposits found in one of these
plate settings: rift valley, subduction zone, suture zone,
- Why do we think the earth, planets and
sun all had a common origin? Cite three lines of
- How are Archean rocks different
Proterozoic rocks? Be sure to describe both the
rocks and their plate tectonic setting.
- What evidence supports the interpretation that a
supercontinent 1) formed in Late Proterozoic time, and
2) broke up just at the beginning of the Cambrian?
- Cambrian rocks in North America are dominated by quartz
sandstones; Ordovician rocks are mostly limestones. What
can you say about depositional environments during the Cambrian
and Ordovician? What caused the change from sandstone deposition
to limestone deposition?
- What kind of plate boundary occupied the east coast of North
America during the Ordovician? What is the evidence
for this interpretation?
- How do we know the age of the Earth? Be sure to include at
least three different ways we estimate the
- Describe the history of the Earth's atmosphere and
oceans. Include a description of ALL of Earth's
atmospheres over time, where the air and water came
from, and the evidence for each atmosphere.
- How does our model of the origin of the solar system explain
- There is an asteroid belt between Mars and Jupiter
- All the planets go around the sun in the same direction
- The major planets are in roughly circular orbits
- The overall density of the Earth is the same as the overall
density of meteorites.
- The density and composition of the surface rocks of the Earth
are different than the density and composition of meteorites.
Potential Essay Questions
1. For the exam, I will choose at
least one of the following geologic settings for analysis. Your
job is to do ALL FIVE of these things:
- to identify the sedimentary
environments represented by these rocks.
- Then identify the tectonic basin
these rocks belong to (rift valley, passive margin,
intracratonic, foreland, forearc, trench, ophiolite) and
- identify what the plate tectonic
setting was at the time these rocks were formed.
- Suggest what other geologic
features you might look for to test your hypothesis.
- Explain your reasoning at every
a. A large portion of the Middle Paleozoic
rocks in the Eastern U.S. are red shales and arkosic sandstones.
Interbedded with the redbeds are thick layers of bentonite,
which is weathered of volcanic ash (assume it was volcanic ash
in the Middle Paleozoic). The sequence of redbeds is thickest in
the east, and thins westward. Further west are found deposits of
gray shales with thin layers of limestone.
b. In the middle of North America are some
very ancient rocks, about a billion years old. At the bottom of
this stack of rocks are basalt flows. On top of the basalt flows
are red sandstones and shales, then white sandstones and
conglomerates. These rocks occupy a strip about 100 miles wide
and 800 miles long through the center of the continent, though
over most of that extent they are buried by younger rocks.
c. The Middle Paleozoic rocks of New
England are typified by gray and brown sandstones and shales.
The sandstones are graywackes with graded bedding that contain
fragments of andesite. The shales are finely laminated and
contain marine fossils.
d. The Coast Range of California contains greenschists of
Mesozoic to Cenozoic age. Mixed into the greenschists are large
chunks of blueschist (boulder to hill-sized), and chert that is
found in both layers and discontinuous boulder-sized blobs. The
green schists are folded and reverse faulted.
e. The Late Paleozoic rocks of the Mid-Atlantic region are
composed of immensely thick layers of red sandstones with ripple
marks and red conglomerates with metamorphic pebbles.
Further west are red-brown shales with mudcracks. To
the east are granite bodies of about the same age.
f. The middle Paleozoic rocks of Colorado include
flat-lying carbonates and shales full of marine fossils.
These rocks are essentially undeformed.