Geology Reference
In-Depth Information
Review Questions
1. The idea that life arose from nonliving matter is called
a. _____ polymerization;
b. _____ abiogenesis;
c. _____ accretion;
d. _____ endosymbiosis;
e. _____ outgassing.
2. One indication that the Proterozoic atmosphere con-
tained some free oxygen is the presence of
a. _____ ultramafi c lava fl ows;
b. _____ the Midcontinent rift;
c. _____ continental red beds;
d. _____ autotrophic prokaryotes;
e. _____ the Wilson cycle.
3. The largest exposed area of the North America cration
is the
a. _____ Minnesota lowlands;
b. _____ American platform;
c. _____ Grand Canyon;
d. _____ Wyoming fold belt;
e. _____ Canadian shield.
4. A complete Wilson cycle involves
a. _____ opening and then closing of an ocean basin;
b. _____ uplift of mountains and their deep erosion;
c. _____ deposition of sandstone, shale, and limestone
in the continental interior;
d. _____ the origin of banded iron formations;
e. _____ the evolution of eukaryotic cells from
prokaryotic cells.
5. The lowermost unit in a greenstone belt is composed
mostly of
a. _____ sandstone;
b. _____ red beds;
c. _____ stromatolites;
d. _____ volcanic rocks;
e. _____ anaerobic bacteria.
6. Many scientists think that the fi rst self-replicating sys-
tem might have been a/an
a. _____ ATP cell;
b. _____ proteinoid;
c. _____ RNA molecule;
d. _____ bacterium;
e. _____ stromatolite.
7. The most widespread Archean-age rocks are those
found in
a. _____ ultramafi c plutons;
b. _____ granite-gneiss complexes;
c. _____ meteorite impact successions;
d. _____ passive continental margin associations;
e. _____ red beds in intracontinental rifts.
8. _____ was a Proterozoic supercontinent made up
mostly of Greenland and North America.
a. _____ Pangaea;
b. _____ Grenville;
c. _____ Laurentia;
d. _____ Sedonia;
e. _____ Newfoundland.
9. The most signifi cant biologic event to take place during
the Proterozoic was the appearance of
a. _____ Pannotian organisms;
b. _____ autotrophic prokaryotes;
c. _____ trilobites and brachiopods;
d. _____ anaerobic proteinoids;
e. _____ eukaryotic cells.
10. Columnar masses of rock produced by the activities of
cyanobacteria (blue-green algae) are
a. _____ orogens;
b. _____ stromatolites;
c. _____ heterotrophs;
d. _____ Rodinians;
e. _____ polymers.
11. Where is the North American craton exposed other
than in the Canadian shield? How do you account for
its presence in this (these) area(s)?
12. What two processes account for adding free oxygen to
the Precambrian atmosphere? What do we mean by
free oxygen, and which of these two processes was most
important?
13. How did the Mesoproterozoic episode of igneous activ-
ity affect the development of Laurentia?
14. The transition from prokaryotic cells to eukaryotic
cells is not recorded by fossils, so how can we fi nd
evidence for how this important event may have
occurred?
15. Proterozoic sedimentary rocks in the northern
Rocky Mountains are 4000 m thick and were
deposited between 1.45 billion and 850 million
years ago. What was the average rate of sediment
accumulation in millimeters per year? Why is this
fi gure unlikely to represent the actual rate of
sedimentation?
16. What evidence indicates that some Eoarchean crust was
present? Why do you think that so few rocks formed
during this time have been preserved in the geologic
record?
17. How do ultramafi c lava fl ows form, and why do you
think they are found in Archean rocks but rarely in
younger ones? Is the presence of these lava fl ows an
exception to the principle of uniformitarianism?
18. What does continental accretion mean and how does it
occur?
19. How do stromatolites form and what is their
signifi cance?
20. Summarize the experimental evidence for the origin of
monomers and polymers.
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