The Precambrian Earth
Practice Test
1.
According to the dates given in the table, when would oxygen start appearing in Earth's atmosphere?
Event Or First Evidence In Fossil Record
Approximate Geological Time
Bacteria
3 b.y.b.p
Green algae
1 b.y.b.p
Jellyfish
600 m.y.b.p
Ediacara organisms
550 m.y.b.p
Eurypterids*
510 m.y.b.p
Horn corals*
500 m.y.b.p
First vertebrates
480 m.y.b.p
Spiders
400 m.y.b.p
Sharks
400 m.y.b.p
First jawed fish*
380 m.y.b.p
Ferns
350 m.y.b.p
Earthworms
300 m.y.b.p
Great Permian Extinction Event
250 m.y.b.p
Drastic geographic and climatic changes
248 m.y.b.p
First dinosaurs*
220 m.y.b.p
First mammals
210 m.y.b.p
Ginkgo biloba
200 m.y.b.p
Abundant ammonites*
180 m.y.b.p
Archaeopteryx*
140 m.y.b.p
First flowering plants
120 m.y.b.p
Ants
100 m.y.b.p
Cretaceous-Paleogene Extinction Event
66 m.y.b.p
Camel
35 m.y.b.p
Grass
20 m.y.b.p
Australopithecus afarensis (“Lucy”)
4 m.y.b.p
a.
3 billion years ago
b.
1 billion years ago
c.
600 million years ago
d.
550 million years go
2.
What type of igneous rocks are associated with oceanic-continental convergences?
a.
granite and diorite
b.
granite and andesite
c.
rhyolite and granite
d.
gabbro, basalt, and sedimentary rocks
3.
Which type of cell shown in the figure existed first?
a.
both came into existence at the same time
b.
B
c.
A
d.
it is impossible to tell
4.
According to the figure, after four half-lives (22,820 years), how much C-14 would be left?
a.
25%
b.
6.25%
c.
10%
d.
0%
5.
Fossils of __________ from late Proterozoic rocks are found in all parts of the world.
a.
the Burgess Shale fauna
b.
trilobites
c.
corals
d.
the Ediacaran fauna
6.
What is at the bottom of the geologic time scale?
a.
the oldest division of time
b.
the Silurian Period
c.
the youngest division of time
d.
the Cenozoic Era
7.
The Appalachian Mountains are an example of mountains that formed at __________.
a.
divergent boundaries
b.
convergent boundaries
c.
spreading centers
d.
fault-block areas
8.
Why are salinities lower than average in some areas close to the equator?
a.
larger clouds
b.
stronger winds
c.
rapid evaporation
d.
abundant precipitation
9.
The oldest rocks on Earth are __________.
a.
3.5 billion years old
b.
1 to 2 billion years old
c.
1.6 to 1.8 million years old
d.
3.96 to 3.8 billion years old
10.
Why don't Archean and Proterozoic rocks have iron oxides?
a.
there wasn't any iron in rocks of that age
b.
there was too much iron to be oxidized
c.
there weren't any stromatolites at that time
d.
there wasn't any free oxygen in the atmosphere
11.
According to the graph, which salt is the most abundant in sea water?
sodium chloride (NaCl)
23.48 g
magnesium chloride (MgCl
2
)
4.98 g
sodium sulphate(Na
2
SO
4
)
3.92 g
calcium chloride (CaCl
2
)
1.10 g
potassium chloride (KCl )
0.66 g
sodium nicarbonate (NaHCO
3
)
0.19 g
potassium bromide (KBr)
0.10 g
a.
potassium bromide
b.
sodium sulfate
c.
sodium chloride
d.
magnesium chloride
12.
What does a disconformity in a sedimentary rock sequence represent?
a.
a volcanic eruption
b.
a flood event
c.
a gap in the rock record
d.
duplicated strata in the rock record
13.
A gravel-sized particle in a conglomerate is __________ the conglomerate rock.
a.
always ten times older than
b.
younger than
c.
the same age as
d.
older than
14.
What marks the end of the Proterozoic Eon?
a.
free oxygen
b.
mammals
c.
the first appearance of organisms with hard parts
d.
oxygen breathing organisms
15.
How are microcontinents fused together?
a.
by seams called orogens
b.
the erosion of mountains
c.
by seams called faults
d.
by molten rock
16.
How were asteroids and meteorites a heat source for Precambrian Earth?
a.
Their impact on Earth generated energy.
b.
Their radioactive decay of isotopes generated energy.
c.
Their bombardment of Earth caused them to sink to the core.
d.
Their gravitational contraction generated energy.
17.
According to the figure, where is an earthquake's focus most likely to occur?
a.
in the middle of the Pacific Ocean
b.
in northern Eurasia
c.
along the west coast of North America
d.
near the south pole
18.
The inner and outer core, mantle, and crust of Earth all have __________.
a.
different densities
b.
been rigid since the formation of Earth
c.
have the same specific gravity
d.
the same densities
19.
Places where two tectonic plates are moving away from each other are called __________.
a.
convergent boundaries
b.
divergent boundaries
c.
transform boundaries
d.
earthquake boundaries
20.
What geologic principle states that in an undisturbed rock sequence, the oldest rocks are on the bottom and the youngest are on the top?
a.
cross-cutting relationships
b.
uniformitarianism
c.
superposition
d.
original horizontality
