Download Chapter 3—Time and Geology

The Earth Through Time
CHAPTER 3—TIME AND GEOLOGY
Select the best answer.
1.
What is the science of determining rock ages called?
a. geochronology
b. relative age dating
c. actual age dating
d. absolute age dating
e. radioactive age dating
2.
Relative time does not have _________.
a. Arrangement.
b. Years.
c. Sequences.
d. Order of events.
e. None of the above.
3.
Relative time is based on ______ an absolute time is based on _______.
a. Years, fossils.
b. Radiometric dating, principles.
c. Paleozoic, Precambrian.
d. Dates, sequence.
e. Principles, radiometric dating.
4.
Which of the following terms is commonly used to name time units?
a. Local geography.
b. Mountain ranges.
c. Ancient Welshmen tribes.
d. Predominant rock types.
e. All the above.
5.
What is the name of the youngest eon?
a. Proterozoic.
b. Phanerozoic.
c. Archean.
d. Hadean.
e. Mesozoic.
6.
The largest time unit is the ______.
a. Eon.
b. Period.
c. Epoch.
d. Age.
e. Era.
7.
The prefix eo is from the Greek for
a. dawn.
b. ancient.
c. middle.
d. recent.
e. new.
8.
The Era with the name meaning “recent life” is
a. Proterozoic.
b. Cenozoic.
c. Archean.
d. Mesozoic.
e. Pleistocene.
9.
Boundaries in the geologic time chart are based on ______________.
a. Absolute dates determined by radioisotope dating.
b. Impacts by meteorites.
c. Eras.
d. Important changes in plant and animal life.
e. Minor changes in plant and animal life.
10.
Which time span contains 87% of the Earth history?
a. Pleistocene Epoch
b. Precambrian
c. Cambrian Period
d. Cenozoic Era
e. Phanerozoic Eon
11.
What time unit does not have any rock record?
a. Hadean.
b. Silurian.
c. Cambrian.
d. Miocene.
e. Archean.
12.
The Neogene and Paleogene replaced which of the following time periods?
a. Mesozoic.
b. Cretaceous.
c. Tertiary.
d. Paleozoic.
e. Cenozoic.
13.
The Cambrian Period was named by ________.
a. James Hutton
b. Adam Sedgwick
c. William Smith
d. Nicolas Steno
e. James Powell
14.
What time system was named based on the occurrence of coal?
a. Cambrian.
b. Permian.
c. Jurassic.
d. Carboniferous.
e. Holocene.
15.
Which era has the periods named based on a tri-fold division?
a. Mesozoic.
b. Cenozoic.
c. Cambrian.
d. Triassic.
e. Devonian.
16.
The Cretaceous name is derived from the _______ formed at that time.
a. Coal
b. Chalk
c. Chert
d. Oil
e. Creeks
17.
Early attempts at determining the age of the Earth include which of the following?
a. Biblical.
b. Ocean Salinity.
c. Cooling Rates.
d. Sediment deposition rates.
e. All the above.
18.
Why did the age of the Earth as calculated by the salinity of the ocean fail?
a. Salinity of the oceans is too low.
b. Oceans are too hot.
c. Did not account for the recycling of the salt.
d. Salt was added for outer space.
e. Dinosaurs roamed the Earth.
19.
Lord Kelvin calculated the age of the Earth at between 20 and 40 million years
based on the cooling rate of a sphere. Why was he wrong?
a. The initial heat was lower than estimated.
b. Added heat from radioactivity.
c. Used the wrong material to simulate the Earth.
d. The initial heat of the Earth was higher than estimated.
e. All, but a.
20.
What is the center of an atom called that contains the protons and neutrons?
a. Nucleus
b. Electron
c. Element
d. The spot
e. Positron
21.
Which constituent of an atom carries a positive charge?
a. Neutron
b. Electron
c. Proton
d. Alpha
e. Bata
22.
The number of protons in an atom determines the __________.
a. Number of electrons.
b. Charge it is.
c. Mass it is.
d. Element it is.
e. Angle of the protons.
23.
An isotope is formed when a ________ is lost.
a. Neutron
b. Electron
c. Proton
d. Alpha
e. Bata
24.
The discharge of alpha particle reduces the number of protons by ____.
a. 1.
b. 2.
c. 3.
d. 4.
e. 5.
25.
What is it called when a neutron splits into a proton and an electron?
a. Alpha.
b. Gamma.
c. Bata.
d. Delta.
e. Both a. and c.
26.
Why can the radioactive decay of an element be used as a clock?
a. Long time frame that radioactivity takes place in.
b. Short time frame that radioactivity takes place in.
c. Only affected by changes in pressure.
d. Affected by pressure, temperature, and chemical reactions.
e. Unaffected by pressure, temperature, and chemical reactions.
27.
In order to measure the number of atoms in a sample, a mass spectrometer is
used. How does the mass spectrometer measure the number of atoms?
a. Atoms are spun in a centrifuge and the heavier atoms move towards the
center.
b. Charged atoms passed by a powerful magnet and are deflected at angles
based on the charge to mass ratio.
c. Atoms are weight on a mass balance.
d. Atoms are combined to form a larger mass.
e. Mass spectrometer does not measure atoms.
28.
What rock type provides the best age dates?
a. Metamorphic.
b. Sedimentary.
c. Zircon.
d. Igneous.
e. Halite.
29.
What is it called when 50% of the parent decays to the daughter?
a. 1/3 life.
b. 2/3 life.
c. Whole life.
d. 1/2 full.
e. 1/2 life.
30.
What radioisotope system would you use to date muscovite mica?
a. 87Rb - 87Sr.
b. 40K - 40Ar.
c. 238U - 207Pb.
d. 235U - 206Pb.
e. 207Pb - 206Pb.
31.
14C
32.
Radiometric method that uses isochron plots:
a. Rb/Sr
b. 14C
c. K/Ar
d. U-Pb
e. fission track
33.
What age date check can be used with the Uranium – Lead system?
a. Pb/Sr
b. 14C/14N
c. K/Ar
d. Pb/Pb
e. Fission track
34.
The half-life of 14C is
a. 704 x 106 years.
b. 4,468 x 106 years.
c. 1,251 x 106 years.
d. 5,730 years.
e. 4.6 x 106 years.
35.
In the Potassium – Argon system, Potassium breaks down into both Argon and
calcium. Why not use the Potassium – Calcium system?
a. 40Ca derived from Potassium cannot be distinguished for existing 40Ca.
b. Calcium cannot be measured by a mass spectrometer.
c. Potassium cannot be measured by a mass spectrometer.
d. Calcium is lost by pressure.
e. Calcium is too big.
36.
14C
37.
14C
– 14N radioisotope system is best for dating ___________.
a. Organic matter.
b. Zircon crystals in volcanic ash.
c. Minerals in an igneous rock that have been reheated and compressed.
d. Minerals in sediments that have been heated by a lava flow.
e. Mica.
is formed form ______.
a. 87Rb.
b. 40K.
c. 238U.
d. 14N.
e. 207Pb.
system works because the Sun imparts _______ continuously to the upper
atmosphere.
a. Photons
b. Cosmic rays
c. Fission tracks
d. Heat
e. Both a. and d.
38.
Fission tracks are formed when fast moving particles _______________.
a. Collide with each other.
b. Repair preexisting flaws in the crystalline structure.
c. Tear electrons off atoms producing a positive repulsion charge.
d. Fuse atoms together on the crystal lattice.
e. Tear electrons off atoms producing a negative repulsion charge.
39.
What type of mineral produced the oldest known age of 4.28 billion years?
a. Mica
b. Augite.
c. Quartz.
d. Feldspar.
e. Zercon.
40.
Samples from meteorites have ages of ________.
a. 4.56 billion years.
b. 4.36 billion years.
c. 3.3 billion years.
d. 4.28 million years.
e. 4.0 million years.
Answers to Questions
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
a
b
e
e
b
a
a
b
d
b
11.
12.
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14.
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20.
a
c
b
d
a
b
e
c
b
a
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30.
c
d
a
b
c
e
b
d
e
a
31.
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39.
40.
a
a
d
d
a
d
b
c
e
A
TEST 2
1. Which of these geochronologic units from the geologic time scale typically cover the longest amount of
time?
a. eras
b. eons
c. epochs
d. periods
e. systems
Ans: b
Feedback: See pages 30-31
2. Which of these geochronologic units from the geologic time scale typically cover the shortest amount of
time?
a. eras
b. eons
c. epochs
d. periods
e. systems
Ans: c
Feedback: See pages 30-31
3. Which of these formal eons is the oldest?
a. Phanerozoic
b. Proterozoic
c. Archean
d. Hadean
Ans: c
Feedback: See pages 30-31
4. Which of these formal eras is the youngest?
a. Mesozoic
b. Neoproterozoic
c. Paleozoic
d. Paleoproterozoic
e. Cenozoic
Ans: d
Feedback: See pages 30-31
5. The dinosaurs lived during which era?
a. Paleozoic
b. Neoproterozoic
c. Mesozoic
d. Precambrian
e. Cenozoic
Ans: c
Feedback: See page 30
6. The daughter product eventually formed by the complete decay of uranium is:
a) thorium
b) argon
c) lead
d) strontium
e) radium
Ans: c
Feedback: See pages 37-38
7. Which naturally radioactive element listed below is used for radiometric dating, forms in the
atmosphere, combines with oxygen to produce a radioactive gas, becomes incorporated into plants, and
is eaten by animals in the food chain?
a. argon
b) carbon
b. radon
d) nitrogen
e) oxygen
Ans: b
Feedback: See pages 42-43
8. Charged particles from radioactive decay pass through a mineral's crystal lattice and leave trails of
damage called:
a) isotopes.
b) xenoliths.
c) mica flakes.
d) fission tracks.
e) beta particles.
Ans: d
Feedback: See page 44
9. In the figure below, how old is unit Y in section A?
a.
b.
c.
d.
older than 450 million years, but younger than 480 milion years
younger than 450 million years
older than 480 million years
older than 480 million years, but younger than 450 milion years
Ans: a
Feedback: See page 40
10. In the figure below, which unit in section B is most likely to be the same age as unit Y in section A?
a.
b.
c.
d.
e.
unit A
unit B
unit C
unit D
unit E
Ans: d
Feedback: See page 40
11. In the figure below, how does the age of unit D compare to unit C?
a.
b.
c.
d.
Units D and C are the same age.
Unit D is older than unit C.
Unit D is younger than unit C.
Relative age cannot be determined from this diagram.
Ans: b
Feedback: See page 40
12. Why are Earth rocks younger than Moon rocks and meteorites?
a. The Earth is younger than the Moon and the meteorites.
b. Radiometric dating works differently on Earth than it does on other planets.
c. The Earth formed from a collision of a meteorite with the Moon.
d. The Earth is geologically active and older rocks may have been altered and converted to
other rocks by geologic processes such as erosion, metamorphism, or melting.
Ans: d
Feedback: See page 45
13. Which type of rock is best for age dating?
a. shale
b. igneous
c. limestone
d. metamorphic
e. coal
Ans: b
Feedback: See pages 38-39
14. How do scientists presently determine the age of the Earth?
a. evidence from fossils
b. adding up generations in the Bible
c. calculating the rate of delivery of salts to the ocean
d. radiometric dating
e. calculations involving rates of deposition and total thickness of the sedimentary record
Ans: d
Feedback: See page 45
15. The atomic number of uranium is 92 and its atomic mass number is 235. Knowing this, how many
protons does it have?
a. 235
b. 184
c. 118
d. 92
e. The exact number cannot be determined from the information given.
Ans: d
Feedback: See page 36
TEST 3
1.
The geologic time scale was originally based on
a. the succession of fossil assemblages.
b. the theory of organic evolution.
c. the rock record.
d. the absolute age of rocks based on isotope age dates.
2.
The dating method that places geologic events in a chronological order as determined from their
position in the rock record.
a. relative dating
c. isotopic dating
b. absolute dating
d. neutron dating
3.
All the rocks formed or deposited during a specific time interval are called __________ units.
a. rock interval.
b. formation.
c. time-rock units.
d. time units.
4.
The correct order of time stratigraphic units from largest to smallest is
a. age, era, epoch, period.
c. age, epoch, era, age.
b. period, epoch, age, era.
d. era, period, epoch, age.
5.
The Carboniferous Systems of Europe and Britain correspond to what systems of North America?
a. Triassic and Jurassic
b. Cambrian and Ordovician
c. Cretaceous and Paleogene
d. Mississippian and Pennsylvanian
6.
The atomic number of an atom is the number of
a. protons and neutrons in the nucleus. c. protons in the nucleus.
b. neutrons in the nucleus.
d. electrons in the outer shell.
7.
An alpha particle is composed of
a. 2 electrons.
b. 2 neutrons.
c. 2 neutrons, 2 protons.
d. 2 protons, 2 electrons.
8.
An element that has the same atomic number, but different atomic weights is an
a. ion.
c. atom.
b. isotope.
d. element.
9.
The use of radioactive elements has proven successful for determining absolute (Quantitative) ages
because
a. most have very long half-lives.
b. they are easily found in the field.
c. they are abundant in the Earth’s crust.
d. the rate of decay is constant for a particular element.
10.
An isotope is an atom of an element with
a. the same atomic number, a different number of electrons, but the same number of neutrons.
b. the same atomic number, but different numbers of protons and electrons.
c. the same atomic number, the same number of electrons, but a different number of neutrons.
d. a different atomic number, but the same number of electrons and neutrons.
11.
The type of radioactive decay that involves the emission of a high velocity electron from the nucleus
is
a. alpha decay.
c. gamma emission.
b. beta decay.
d. electron reflection.
12.
Three Eons span the time boundaries of the Earth’s history. The three eons from the oldest to
youngest are:
a. Proterozoic, Archeon, Phanerozoic.
b. Archeon, Proterozoic, Phanerozoic.
c. Archeon, Phanerozoic, Proterozoic.
d. Proterozoic, Archeon, Phanerozoic.
13.
The divisions of the Proterozoic Eon from the oldest to youngest given the Earth’s history are:
a. Meso-Archeon, Eo-Archeon, Paleo-Archeon, Neo-Archeon.
b. Paleo-Archeon, Meso-Archeon, Paleo-Archeon, Eo-Archeon.
c. Eo-Archeon, Paleo-Archeon, Meso-Archeon, Neo-Archeon.
d. Neo-Archeon, Meso-Archeon, Paleo-Archeon, Eo-Archeon.
14.
The following represent time divisions in geology which are inclusive—from largest to smallest the
correct order is:
a. Era, Eon, Period, Epoch, Age.
c. Era, Period, Eon, Epoch, Age.
b. Eon, Era, Period, Epoch, Age.
d. Eon, Period, Era, Epoch, Age.
15.
The eon before the Precambrian
a. Phanerozoic.
b. Archeon.
c. Neo-Archeon.
d. Proterozoic.
16.
This type of geologic dating tells which event preceded another or which rock mass is older or
younger.
a. quantitative dating
d. relative dating
b. uniformitarism
e. absolute dating
c. Isotopic dating
17.
An element having the same atomic number but different atomic weight.
a. ion
d. proton
b. atom
e. isotope
c. neutron
18.
Associated with protons in a nucleus are particles having the same mass as protons; however,
when they are electrically neutral they are called
a. Isotopes.
c. alpha particles.
b. electrons.
d. neutrons.
19.
Which of the following rock source materials are used in the Potassium-Argon method?
a. zircon, uraninite
c. muscovite, hornblende, glauconite
b. muscovite, limestone, zircon
d. coralline limestone, muscovite, zircon
20.
Which of the following reflects the correct parent isotope to daughter isotope?
a. potassium – 40, lead – 206
c. uranium – 238, lead – 206
b. thorium – 232, lead – 208
d. potassium – 40, strontium – 87
FILL IN THE BLANK
1.
The oldest rocks of our planet that make up the Archean and Proterozoic are collectively referred to
as the
.
2.
The number of protons in the nucleus of an atom establishes its number of positive charges and is
called
.
3.
The new atom formed from another by radioactive decay, is called
4.
When atoms of the same substance have different mass numbers these variations are
called
.
5
.
Emission in the radioactive decay process, consisting of a form of invisible electromagnetic waves
having even shorter wavelengths than X-rays, is called
.
6. The radioactive dating method using electron capture (where a proton is transformed into a neutron)
and whose half-life is 1251 million years is called
method.
7.
The method of age dating that is based on the content of radiocarbon, which has a short half-life of
5730 years, found in a particular rock is
.
8.
The actual rocks formed or deposited during a specific time interval are called chronostratigraphic
units or ____________________ ___________________.
9.
The science of determining the age of rocks is called ________________________.
10. The term ________________ ________________ was coined in 1822 for strata that included coal
beds in north-central England.
11. The _________________ ____________________ was named in 1834 by a German geologist for
the three-fold division of rocks of this age in Germany.
12. An atom’s ____________ ________________ approximately equals the sum of the masses of its
protons and neutrons.
13. The epoch that represents a subdivision of Neogene and spans from 2 million years to 10-12
thousand years ago is
.
14. The system that takes its name from a province in Russia, and the youngest period in the “ancient
life,” Paleozoic is the
.
15. The parent isotope uranium-235 has a half-life of 704 million years. What is its daughter isotope?
_____________________.
TRUE/FALSE
1.
Eras may be further subdivided into shorter time units called epochs, which in turn can
be further subdivided into periods.
2.
The rocks of the Cambrian System take their names from the Latin name for Wales.
3.
The number of protons in the nucleus of an atom establishes its number of positive
charges and is called its atomic number.
4.
A beta emission is a form of radioactive decay where an electron is emitted from the
nucleus of a radioactive isotope.
5.
Phanerozoic has been divided into three major subdivisions called periods.
6.
The daughter Nuclide of Potassium -40 is strontium -87.
7.
Fission tracks are formed by the passage of nuclear particles emitted during the spontaneous
fission of uranium.
8.
The half-life of carbon 14 is 5730 years.
9.
Actual geologic dating places geologic events, and the rocks representing those events in
sequence.
10.
Source materials for potassium-40 and its daughter isotope Argon 40 would include
muscovite, biotite, hornblende, glauconite, potassium, feldspar, and whole volcanic rock.
ANSWERS
Multiple Choice
1. a
2. a
3. c
4. d
5. d
6. c
7. c
8. b
9. d
10. c
11. b
12. b
13. d
14. b
15. a
16. c
17. e
18. d
19. c
20. c
Fill Ins
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Pre Cambrian
atomic number
daughter element
isotopes
gamma radiation
potassium
Carbon-14
time rock units
geochronology
Carboniferous System
Triassic System
atomic mass
Pleistocene
Permian
Lead-207
True/False
1. F
2. T
3. T
4. T
5. F
6. F
7. T
8. T
9. F
10. T
RESPONSES TO QUESTIONS ACCOMPANYING SELECTED
FIGURES
FIGURE 3–2 (p. 32) The Devonshire strata contained a fossil assemblage characteristic of rocks
elsewhere in Europe that were higher (hence, younger according to superposition) than those
described as Silurian in southern Wales by Murchison.
FIGURE 3–7 (p. 39) The stratum beneath the ash must be older than 453.7 million years.
FIGURE 3–10 (p. 40) If a graph were prepared showing how much sand passed through an
hourglass in each unit of time, the graph would display an inclined straight line, indicating that the
amount of original material lost from the top of the hourglass to the lower half is the same during
each unit of time. Because the amount of original radioactive material that is lost diminishes with
time, the curve on a graph showing radioactive decay would consist of an inclined concave curve.
FIGURE 3–11 (p. 41) The age of a rock having a 207Pb/206Pb of 0.15 would be 2.6 billion years
old.