Deck 19: Precambrian Earth and Life History

Question 1

The oldest rocks (not minerals)on Earth are_____ old.

A)4.6 billion years
B)4.4 billion years
C)4.0 billion years
D)3.8 billion years
E)3.5 billion years

Answer 1

3.8 billion years

Question 2

Proterozoic layered igneous intrusions are the world's major sources of chrome and platinum.

Answer 2

True

Question 3

Archean and Proterozoic greenstone belts formed in similar tectonic settings.

Answer 3

True

Question 4

Earth differentiated during the ____.

A)Hadean
B)Archean
C)Paleoproterozoic
D)Mesoproterozoic
E)Neoproterozoic

Question 5

Organisms are composed of simple monomers.

Question 6

Time divisions in the Precambrian are based on ____.

A)distinct fossil assemblages
B)metamorphic assemblages
C)absolute dates
D)time-stratigraphic units
E)igneous assemblages

Question 7

During the Archean, how long was the length of a day on Earth?

A)36 hours
B)10 hours
C)The same as the length of a day on modern Earth
D)The same as in the present but with no sunlight, i.e., all darkness
E)The same as in the present but there no darkness, i.e., all daylight

Question 8

The prevailing model for the formation of greenstone beds in the Archean is ____.

A)igneous intrusion into a sandstone bed
B)the closing of a back-arc basin
C)a Wilson cycle
D)mid-continental rifting
E)ultramafic lava flows

Question 9

The oldest well-documented stromatolites occur in the ____.

A)Hadean
B)Archean
C)Paleoproterozoic
D)Mesoproterozoic
E)Neoproterozoic

Question 10

The exposed part of the North American craton is the ____.

A)Pacific coast
B)Appalachian Mountains
C)Adirondack Mountains
D)Canadian shield
E)Great Lakes basin

Question 11

All known Proterozoic animals were soft-bodied.

Question 12

Stromatolites are the product of organic activity.

Question 13

Sandstone-carbonate-shale assemblages occur along continental rift margins and intracratonic basins.

Question 14

Granite-gneiss complexes are typical in what age of rocks?

A)Archean
B)Hadean
C)Neoproterozoic
D)Paleoproterozoic
E)Mesoproterozoic

Question 15

Some Paleoproterozoic-age rocks and associated features provide excellent evidence for widespread glaciation.

Question 16

The rate of plate motion was probably slowest in the Archean Eon.

Question 17

The Precambrian comprises what percent of geologic time?

A)99 percent
B)88 percent
C)77 percent
D)66 percent
E)55 percent

Question 18

The boundaries of subunits or smaller cratons within the shield are based on topographic expression of different rock types.

Question 19

Modern eukaryotic cells that contain organelles and mitochondria support the theory of endosymbiosis.

Question 20

Shield areas of continents are found in modern ____.

A)subduction zones
B)continent-continent plate boundaries
C)tectonically inactive regions
D)divergent plate boundaries
E)transform plate boundaries

Question 21

_____ sequences provide evidence for convergent plate boundaries from Neoarchean and Paleoproterozoic rocks.

A)Wilson
B)Rift
C)Sedimentary
D)Ophiolite
E)Granite-gneiss

Question 22

The oldest eukaryotes in the fossil record are at least how old?

A)2.0 billion years old
B)1.2 billion years old
C)1.0 billion years old
D)3.4 billion years old
E)5.0 billion years old

Question 23

The increase in atmospheric oxygen during the Proterozoic was most related to the ____.

A)decrease in global volcanism
B)decrease in ocean sizes
C)process of photosynthesis by bacteria
D)appearance of land plants
E)origin of complex life forms

Question 24

Before the appearance of cells capable of sexual reproduction, ____.

A)there was no life on Earth
B)evolution was comparatively slow
C)evolution was comparatively fast
D)cells could not reproduce
E)multicelled organisms existed

Question 25

The Archean atmosphere can best be described as ____.

A)oxygen-rich
B)nitrogen-rich
C)ozone-rich
D)oxygen-deficient
E)rich in carbon dioxide

Question 26

What term describes molecules that are intermediate between inorganic compounds and living organisms?

A)protobionts
B)proteinoids
C)bacteria
D)amino acids
E)monomers

Question 27

About one-fourth of modern day chrome reserves are in ____ rocks.

A)Hadean
B)Archean
C)Paleoproterozoic
D)Mesoproterozoic
E)Neoproterozoic

Question 28

By ____ years ago, much of Greenland, central Canada, and the north central United States formed one large craton.

A)1.8 million
B)2.0 billion
C)1.6 billion
D)1.6 million
E)1.8 billion

Question 29

Besides iron, banded iron formations contain

A)quartz
B)calcite
C)magnetite
D)chert
E)shale

Question 30

What are small molecules composed of multiple amino acids called?

A)monomers
B)protobionts
C)bacteria
D)proteinoids
E)DNA

Question 31

Organisms are composed of many elements. Which is the least abundant of these?

A)oxygen
B)nitrogen
C)calcium
D)carbon
E)hydrogen

Question 32

The Ediacaran fauna include representatives of the modern phyla ____.

A)Proterozoa, Annelida, and Arthropoda
B)Annelida, Arthropoda, and Cnidaria
C)Proterozoa, Porifera, and Cnidaria
D)Coelenterata, Annelida, and Cnidaria
E)Coelenterata, Proterozoa, and Porifera

Question 33

A complete _____ involves rifting of a continent and the opening of an ocean basin with passive continental margins on both sides.

A)Archean cycle
B)orogeny
C)Wilson cycle
D)rift sequence
E)tide sequence

Question 34

Outgassing and ____ are probable sources for Earth's early water vapor.

A)solar wind
B)icy comets
C)photochemical dissociation
D)land plants
E)the ozone layer

Question 35

Archean rocks in South Africa have yielded more than 50% of the world's ____ since 1886.

A)lead
B)copper
C)gold
D)zinc
E)iron

Question 36

A(n)_____ is a linear or arcuate deformation belt in which many of the rocks have been metamorphosed by intruded magma.

A)orogen
B)craton
C)greenstone belt
D)supercontinent
E)midcontinent rift

Question 37

The earliest atmosphere of Earth was ____.

A)essentially the same as our modern atmosphere
B)composed entirely of nitrogen
C)composed of ozone and hydrogen
D)blown into space by solar wind
E)composed entirely of ozone

Question 38

The large Proterozoic landmass known as Laurentia was composed of ____.

A)Europe, Asia, Scandinavia, and NW Scotland
B)North America, South America, Greenland, and the Baltic Shield
C)North America, Greenland, NW Scotland, and the Baltic Shield
D)Greenland, NW Scotland, Baltic Shield, and Europe
E)Greenland, Iceland, Nova Scotia, and the Baltic Shield

Question 39

Before Earth had a differentiated core, the solar wind would have stripped any gases from the surface because of the lack of a(n)_____.

A)continental crust
B)volcano
C)atmosphere
D)sedimentary sequence
E)magnetosphere

Question 40

Pegmatites are associated with ____ rocks and contain ____, ____, and ____.

A)greenstone belt volcanic; copper; lead; zinc
B)greenstone belt volcanic; rubidium; beryllium; lithium
C)granitic; lithium; zinc; gold
D)granitic; lithium; beryllium; rubidium
E)sedimentary; gold; chrome; platinum

Question 41

Describe the Faint Young Sun Paradox.

Question 42

_______________ is an informal term that encompasses all geologic time from 4.6 to 4.0 billion years ago.

Question 43

Between 1.3 and 1.0 billion years ago, the Grenville orogeny occurred in the supercontinent __________.

Question 44

What are prokaryotic organisms?

Question 45

Early gases that had begun to accumulate around Earth during the Early Archean were lost because of a lack of a(n)____________________.

Question 46

The Grenville orogen probably resulted from closure of a(n)__________, the final stage in a Wilson cycle.

Question 47

Glacial deposits, as well as striated and polished bedrock, indicate that two major episodes of glaciation took place during the _______________.

Question 48

What is the first supercontinent recognized with some certainty, and when did it begin fragmenting?

Question 49

What are heterotrophic organisms?

Question 50

What does the appearance of red beds in the geologic record indicate about the atmosphere?

Question 51

What do the Ediacaran fauna represent, and why are they important?

Question 52

Why are ultramafic volcanics rare in rocks that are much younger than Archean in age?

Question 53

Continental growth during the Early Proterozoic development of Laurentia was related to ____________________ of Archean age cratons.

Question 54

Early organisms played a role in the accumulation of free oxygen through the process of ____________________.

Question 55

What two processes, which began during the Archean, can account for the introduction of free oxygen into the atmosphere?

Question 56

The assemblage of sandstone-carbonate-shale is probably indicative of ____________________ (in depth)water shelf environment.

Question 57

What are the two major rock types that characterize Archean shield areas?

Question 58

Briefly explain the difference between the tectonic setting of shield areas during the Precambrian and since the onset of the Phanerozoic.

Question 59

Sandstone-carbonate-shale assemblages were deposited along _______ continental margins during the Proterozoic.

Question 60

Continents are cored by large areas of exposed ancient rocks called ____________________, which are tectonically inactive regions.