Deck 11: The Hadean and Archean Eons of Precambrian Time

Question 1

The Hadean and Archean eons encompasses about __________ percent of Earth's history.

A) 90
B) 45
C) 25
D) 5

Answer 1

B

Question 2

The origin of Earth's early felsic crust was probably

A) partial melting of subducted slabs of crust.
B) melting of oceanic lithosphere.
C) meteorite impacts.
D) magma oceans.

Answer 2

B

Question 3

Greenstone belts were formerly

A) oceanic crust that was altered by extraterrestrial impacts.
B) forearc basins and deformed oceanic crust that have not been metamorphosed.
C) protocontinents, stromatolites, and island arcs.
D) forearc basins, deformed oceanic crust, and volcanic arcs.

Answer 3

D

Question 4

Although the origin is unclear, most cratons of the world experienced major episodes of metamorphism between about __________ billion years ago.

A) 1.3 and 2.3
B) 2.3 and 2.7
C) 2.7 and 3.3
D) 3.3 and 3.5

Question 5

The silica in Archean chert came from

A) banded iron formations.
B) greenstone belt metamorphism.
C) submarine volcanic eruptions.
D) bacterial action in sediments.

Question 6

Microcontinents were made from

A) weathering and metamorphism of seafloor basalts.
B) numerous felsic bodies of rock that emerged during Archean.
C) island arcs with mafic and intermediate volcanoes.
D) meteorite and comet impacts on the seafloor.

Question 7

The axial tilt of Earth is likely due to

A) large asteroid impacts.
B) once-great magma oceans.
C) the surface distribution of continents.
D) volcanic events of great size.

Question 8

The first surface of Earth was likely a

A) feldspar-rich crust.
B) magma ocean.
C) layer of heavy metals.
D) water ocean.

Question 9

Before the formation of our solar system, the event that must have preceded the formation of our solar nebula was

A) the magma ocean.
B) a supernova.
C) the arrival of comets.
D) accretion of Earth.

Question 10

The origin of Earth's Moon was

A) waves and tides of the magma ocean.
B) accretion of a swarm of asteroids that once orbited Earth.
C) an asteroid captured by Earth's gravity.
D) the impact of a Mars-sized planet shortly after Earth's accretion.

Question 11

The reason that Archean protocontinents were small is that

A) Earth's interior was not hot enough during Archean to make much felsic crust.
B) Earth's interior was very hot during Archean and rifting was quite common.
C) the Archean crust was very thin and largely basaltic in composition.
D) the Archean crust was more quickly destroyed by erosion and subduction than later-formed crust.

Question 12

From those listed below, select the incorrect reason that Archean rocks are rare on the Earth's surface.

A) Erosion has destroyed many Archean rocks.
B) Archean rocks have plentiful, yet small, index fossils.
C) Archean rocks tend to be buried below sedimentary and volcanic rocks.
D) Metamorphism has altered many Archean rocks so that they cannot be dated properly.

Question 13

The origin of Earth's early atmosphere was because of

A) the impact of a Mars-sized planet.
B) atmospheres of impacting asteroids and comets.
C) degassing of Earth's interior over time.
D) chemical reactions in the early crust.

Question 14

Archean greenstone belts sit among masses of

A) chlorite-bearing mafic metamorphic rocks.
B) banded iron formations and extraterrestrial impact craters.
C) sedimentary rocks made of weathered volcanic rocks.
D) high-grade felsic metamorphic rocks.

Question 15

The oldest known crustal materials, which are fragments from crustal rocks about 4.4 billion years old, are

A) volcanic rock fragments.
B) quartz crystals.
C) zircon grains.
D) uranium-bearing rocks.

Question 16

Meteorites made of iron with olivine crystals are called

A) asteroids.
B) iron meteorites.
C) stony meteorites.
D) stony-iron meteorites.

Question 17

The maria on the Moon were formed by

A) magma oceans.
B) volcanic events of great size.
C) water oceans.
D) asteroid impacts followed by great lava flows.

Question 18

Isotopic evidence shows that photosynthetic life existed on Earth as early as _________ billion years ago, but the oldest fossil evidence of life on Earth is about __________ billion years ago.

A) 4.5; 3.7
B) 4.5; 3.5
C) 3.7; 3.5
D) 3.7; 2.5

Question 19

Our planet's early water ocean was formed by

A) atmospheres of impacting asteroids and comets.
B) chemical reactions in the early atmosphere.
C) volcanic emission of water vapor.
D) melting of polar ice caps.

Question 20

Evidence in the form of __________ allows us to know the age of the universe and distant galaxies.

A) the configuration of a spiral galaxy
B) the age of stony meteorites
C) an increase in wavelength of distance star light
D) gravitational collapse of dense clouds of interstellar gas

Question 21

In order of increasing amount, the relative proportion of sedimentary rocks being formed 2.5 billion years ago was

A) evaporites, carbonates, cherts, and siliciclastics.
B) siliciclastics, cherts, carbonates, and evaporates.
C) carbonates, cherts, and siliciclastics.
D) siliciclastics, cherts, and carbonates.

Question 22

The survival of pyrite grains transported in streams along with other Archean sediments shows us that bacteria-produced oxygen was

A) very rapidly building in the early atmosphere.
B) being taken out of the atmosphere by chemical sinks in early Earth.
C) not yet forming and would require more time for evolution to change that fact.
D) no match for the vast quantities of oxygen produced in other ways.

Question 23

The first protective external structure of living organisms must have been

A) methane and ammonia.
B) amino acids.
C) primordial soup.
D) semi-permeable membranes.

Question 24

Organic compounds of the kind required for the origin of early life readily dissolve in the warm waters of the mid-ocean ridge area, but these compounds are protected in that warm area by

A) nickel and zinc.
B) anoxic waters.
C) water pressure.
D) lack of phosphorus.

Question 25

The nucleic acid likely to have been present in the earliest life forms was the genetic basis for an early global ecosystem on Earth called

A) amino acid planet.
B) DNA world.
C) RNA world.
D) nucleic acid world.

Question 26

In each of the three chemosynthetic reactions (hydrogen oxidation, sulfur reduction, and methane production), what is produced?

A) Energy
B) Methane
C) Hydrogen
D) Water

Question 27

Early life likely originated at or near a __________ because trace amounts of __________ would have been toxic to early life.

A) lake or ocean; oxygen
B) lake or ocean; methane
C) mid-ocean ridge; oxygen
D) mid-ocean ridge; methane

Question 28

The photosynthetic organisms in Archean stromatolites were

A) archaea.
B) kimberlites.
C) cyanobacteria.
D) eukaryotic cells.

Question 29

The difference between the habitat of sulfur-reducing archaea and hydrogen-oxidizing bacteria is

A) photosynthesis.
B) salt tolerance.
C) warm adaptation.
D) oxygen requirements.

Question 30

__________ is to prokaryotes as photosynthesis is to plants.

A) Amino acid production
B) Banded-iron formation
C) Chemosynthesis
D) Warm adaptation