Performance Benchmark E.12.C.1
Students know how successive rock strata and fossils can be used to confirm the age, history, and
changing life forms of the Earth, including how this evidence is affected by the folding, breaking,
and uplifting of layers. E/S
Imagine that your favorite author has just released a book and you were able to attain an
advanced copy. You set aside some time to begin this much anticipated adventure only to find
out that the book is incomplete. Upon turning to the first chapter, all that is written is the title
followed by 30 pages of blank paper; worse still this pattern repeats for the next several chapters.
Eventually a single word appears, followed by mainly blank pages in which only a few single
words are scattered. An appreciable way into the book you discover short phrases, eventually
followed by longer phrases, and finally complete sentences. From this point the remaining
portion of the story is captivating, and you experience a robust story of life, death, and change
with fully developed characters and an intriguing narrative. At the end of the book you are left
with many questions as to how this story began and to the characters’ origins and early
experiences. Just like the above scenario, the story of Earth and the life it supports has changed
throughout time. The charge of the geoscientist is to piece together the parts of the story that are
incomplete.
One of the challenges facing geoscientists is to determine the exact age and history of Earth that
has brought it to its current situation. Earth is a dynamic planet that has evolved over time. As a
result, continents have been moved, mountains created and leveled (eroded), meteors impacted,
volcanoes erupted, earthquakes jolted, and rocks recycled and destroyed by the process plate
tectonics. Earth’s biologic diversity and evolution have also been critical players in our
changing planet. To help piece together the story of Earth an understanding of the rock cycle,
importance of fossils, geologic timescale, and age dating techniques – both relative and absolute
- need to be explored.
Rock Cycle
Rocks are naturally occurring aggregates of one or more minerals. All rocks are composed of
material that has been present on Earth since it first formed – excluding that material which has
been delivered by meteorites. Although the constituent material used to create rocks has not
changed appreciably over time, their arrangements have. The rock cycle (Figure 1) is a model
that illustrates the changes to rocks that have taken place through time. Rocks are recycled into
other rocks through processes which occur in mainly two locations; at or near Earth’s surface
such as weathering, erosion, and deposition; and deep below the surface such as melting and
increased heat and pressure. Most rocks are formed from other rocks and a “rock” may take
more than one path through the rock cycle. The arrows on the rock cycle diagram shows various
processes one rock type (i.e. metamorphic) could advance through in order to become a different
rock type (i.e. sedimentary).
Using the rock cycle diagram, let’s examine the processes a metamorphic rock passes through to
become a different rock type. Starting at metamorphic rock and following the outside arrows
clockwise our metamorphic rock would need to experience an increase in temperature to the
point of melting it, creating magma. Eventually this magma body would enter an environment
where the heat contained would transfer from it (cooling) and the process of solidification
(crystallization) occurs. This rock is now classified as an igneous rock. Continuing clockwise
from igneous, several more changes must occur in order to turn this igneous rock into a
sedimentary rock. The igneous rock needs to be subjected to the agents of weathering and
erosion, which over geologic time creates pieces or fragments of rock called sediment. As this
sediment piles up, compaction and cementation turn the loose sediment into a solid rock through
the process of lithification. This rock is now classified as a sedimentary rock. Continuing
clockwise this sedimentary rock will become a metamorphic rock with the addition of heat and
pressure causing a partial melting of some of the minerals in the sediment. This process is
referred to as metamorphism and results in creation of a metamorphic rock. The straight arrows
within the rock cycle diagram indicate that any one rock type can turn into any other rock type
by passing through several common processes.
Figure 1. The Rock Cycle (from http://piru.alexandria.ucsb.edu/collections/geosystems/geosystems11-06.jpg).
For an interactive rock cycle animation, go to
http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm
For additional information related to the rock cycle and three classifications of rocks, go to
http://www.windows.ucar.edu/tour/link=/earth/geology/rocks_intro.html
Fossils
Fossils are the remains, molds, or traces of living organisms preserved in media such
as sedimentary rock (i.e. sandstone, siltstone, shale or limestone), amber, ice, or tar. Fossils
provide evidence of past forms of life and are used by paleontologists, geologists, biologists and
others to learn about the past history of Earth. The oldest fossils found indicate life on our planet
began at an age of well over 3 billion years ago. These organisms were simple, single-celled
organisms. Increasingly complex multi-cellular organisms began to evolve, as preserved in rock,
dating from about one billion years old. A significant number of fossils (and diversity) begin
around 550 million years ago, as organisms with hard parts burst onto the scene – this is referred
to as the Cambrian explosion.
For an animation showing how fossils form, go to
http://www.classzone.com/books/earth_science/terc/content/visualizations/es2901/es2901page01
.cfm?chapter_no=visualization
For detail on the Cambrian explosion, go to
http://www.ucmp.berkeley.edu/cambrian/camb.html
The Principle of Superposition states that, for an undisturbed rock sequence the oldest rock layer
is on the bottom, and the higher up one travels, the younger the rock layers become. When
comparing fossils in undisturbed strata, fossils can be found in upper strata which, although
different from fossils in lower strata, resemble those fossils. This suggests links between modern
forms and older forms, as well as divergent pathways from common ancestors. If we examine
fossils found in various layers of rock, and look at progressively older layers, we can see that
there is a layer below where no human fossils are naturally found. As we progress backward in
time, we will eventually see a layer below where no fossils of birds, no mammals, no reptiles, no
fish, and eventually, no animal of any kind are found. This is evidence that the kinds of plants
and animals, and other organisms have changed over time and is called the Law of Fossil
Succession.
Further detail about fossils can be found in the TIPS L12D3 performance benchmark.
To learn more about the importance of the fossil record and the law of fossil succession, go to
http://pubs.usgs.gov/gip/fossils/succession.html
and http://www.fossilmuseum.net/fossilrecord.htm
There are gaps in the branches of the fossil records of life. Gaps exist in the fossil record, partly
because plants, microorganisms, and soft shelled organisms (majority of marine animals), are not
likely to fossilize. Even hard bodied organisms do not frequently fossilize. In addition, changes
in the land resulting from forces on our dynamic planet (i.e., erosion, metamorphosis, and
geological events) can destroy fossils if they were present. However, the fossil record does
provide significant evidence of evolution and of the history of life on earth.
For more information on fossils, visit
http://www.museum.vic.gov.au/prehistoric/what/index.html
and http://www.museum.vic.gov.au/dinosaurs/sciprocess.html
Geologic Time
Earth's history has been divided into a series of time intervals (Figure 2). These time intervals
are not equal in duration like hours in a day. Instead they are variable in duration because
geologic time is divided using significant events in the history of the Earth. For example, the
boundary between the Permian and Triassic is marked by a global extinction in which a large
percentage (nearly 90%!) of Earth's plant and animal species went extinct – the end-Permian
mass extinction is perhaps the most severe extinction the planet has seen. Another example is
the boundary between the Precambrian and the Paleozoic which is marked by the first
appearance of animals with hard parts, called the Cambrian explosion occurring some 550
million years ago.
Figure 2. These time scales are drawn to scale so you can compare the relative lengths of geologic time divisions.
(from http://wrgis.wr.usgs.gov/docs/parks/gtime/gtime2.html)
The geologic time scale consists of (from longest to shortest duration) eons, eras, periods, and
epochs. The eon is the largest division of geologic time, which is made up of several eras and
continues for hundreds of millions or billions of years. Essentially there are two eons, the
Precambrian (which covers ~90% of all geologic time) and the Phanerozoic. An era is a
geologic division including several periods, but of shorter duration than an eon. In general, eras
last for many tens or hundreds of millions of years, and are often characterized by distinct lifeforms. The Paleozoic era “age of ancient life” was a time dominated by marine invertebrates.
The Mesozoic era “age of middle life” was a time dominated by reptiles, of which the most
famous were the dinosaurs. The Cenozoic era “age of recent life” is a time dominated by
mammals, of which the most famous are reading this TIPS benchmark. The period is the most
commonly used unit of geologic time, representing one subdivision of an era. Each period
generally lasts for some thirty to eighty million years. Lastly, epochs, only found in the
Cenozoic, are smaller divisions of a period. To describe the current geologic time (from smallest
to largest division), we are in the Holocene Epoch of the Quarternary Period within the Cenozoic
Era of the Phanerozoic Eon.
For detailed information related to the geologic time scale and an interactive model of major
geologic events within the various divisions of time, go to
http://www.palaeos.com/Timescale/default.htm
The Smithsonian interactive geologic timeline is a really great resource for background
information related to geologic time, along with detailed surface and atmospheric conditions,
http://paleobiology.si.edu/geotime/main/
Dating Methods
Dating the age of rocks is critical to reconstructing Earth's history. Geologists rely on two basic
types of dating: relative dating and absolute dating. Relative dating places historical events in
their correct order, but does not yield numerical estimates of how many years ago the events
happened. Absolute dating establishes how many years ago a given event took place. The most
important methods of absolute dating are based on the decay of naturally occurring radioactive
elements. It may seem odd that the two procedures are kept distinct - if scientists can determine
the numerical ages of rocks and fossils, they should be able to put the evidence of ancient life in
the correct historical order. The problem is that only some types of rocks and fossils can be
numerically dated, so all other evidence of ancient life must be related to age-dated material by
the techniques of relative dating.
Relative Dating
James Hutton (known as the Father of Modern Geology) advanced the concept of geologic time
and strengthened the belief in an ancient world. Hutton first proposed formally the fundamental
principle used to classify rocks according to their relative ages. He concluded, after studying
rocks at many outcrops, that each layer represented a specific interval of geologic time. Further,
he proposed that wherever undisturbed layers were exposed, the bottom layer was deposited first
and was, therefore, the oldest layer exposed; each succeeding layer, up to the topmost one, was
progressively younger. This came to be known as the Principle of Superposition.
Figure 3. Superposition (from http://cse.cosm.sc.edu/hses/RelatDat/pages/superpos.htm).
Hutton also proposed the Principle of Uniformitarianism, which states “The present is the key to
the past”. This manner of thinking assumes that geologic forces and processes (gradual as well
as catastrophic) acting on the Earth today are the same as those that have acted in the geologic
past. An example of uniformitarianism would be to observe today how rocks weather into
sediment and pile up (typically in a body of water) and, as more and more weight is added, the
lower layers become compacted and cemented together forming a sedimentary rock – with layers
building horizontally (known as the Principle of Original Horizontality). Upon seeing a
sequence of faulted, folded, or tilted rock layers, one can assume that these layers were originally
deposited horizontal. Once formed, these layers were then subjected to geologic forces that
altered their original state.
To see an animation of how originally horizontal layers become tilted, go to
http://www.classzone.com/books/earth_science/terc/content/investigations/es2903/es2903page04
.cfm
An unconformity is a buried erosion surface separating two rock layers of different ages. An
unconformity represents time during which no sediments were deposited and the local record for
that time interval is missing. The steps required to form an unconformity are; deposition of
sediments creating horizontal rock layers, uplift and tilting, erosion (removal of material),
followed by further deposition (Figure 4).
Figure 4. Steps to create an unconformity
(from http://www.winona.edu/geology/MRW/mrwimages/Earth%20History/angular_uncof.JPG).
For an animation showing the steps to form an unconformity, go to
http://www.classzone.com/books/earth_science/terc/content/visualizations/es2902/es2902page01
.cfm?chapter_no=visualization
The Principle of Cross-Cutting Relations states that any feature that cuts across a layer must be
younger than the layer it cuts through. Igneous intrusions, faults, and erosion surfaces can cut
across any features, including other igneous rocks, other faults, and erosion surfaces. As a
consequence, the principle of cross-cutting relations is extremely important in narrowing the
relative age of a geologic event.
Figure 5. Cross-cutting by erosion.
Figure 6. Cross-cutting by fault.
Figure 7. Cross-cutting by igneous rock.
(from http://cse.cosm.sc.edu/hses/RelatDat/pages/crosscut.htm)
The sequence of geologic events in an area can be solved by applying the fundamental principles
of geologic relative age dating (e.g., Principle of Superposition). In this diagram, which shows a
hypothetical exposure of rock, it is possible to determine the order in which the various geologic
events occurred. See if you can tell the story of how this sequence can to be the way it is – from
oldest to youngest.
Figure 8. Hypothetical exposure of rock (from http://www.nysedregents.org/testing/scire/es606.pdf).
Answer from oldest to youngest;
1. Conglomerate 2. Shale 3.Sandstone 4. Siltstone 5. Limestone 6. Breccia (using the
Principle of Superposition), followed by; 7. Basalt Intrusion (and contact metamorphism)
8. Fault (using the Principle of Cross Cutting Relations) 9. Erosion.
For more background information and examples of relative dating of rock layers, go to
http://gpc.edu/~pgore/geology/historical_lab/relativedating.htm and
http://gpc.edu/~pgore/geology/historical_lab/reldat_exercises.html
Absolute Age Dating of Rocks
Radioactive elements are unstable; they breakdown spontaneously into more stable atoms over
time, a process known as radioactive decay. Radioactive parent elements decay to stable
daughter elements. This decay occurs at a constant rate, specific to each radioactive isotope
(Figure 9), and is not affected by changes in temperature and pressure.
Figure 9. Parents and daughters for some isotopes commonly used to establish numeric ages of rocks
(from http://pubs.usgs.gov/gip/fossils/numeric.html).
Each radioactive isotope has its own unique half-life. A half-life is the time it takes for half of
the radioactive isotope (parent material) to decay to a stable element (daughter product). The
proportion of parent to daughter reveals the number of half-lives, which can be used to find the
age in years.
Figure 10. Radioactive decay graph showing parent isotope decay (red line) and time for each half-life (blue line).
From http://www.palaeos.com/Geochronology/radiometric_dating.htm
For example, if there is an equal amount of parent and daughter (such as; 500 atoms of both
carbon-14 and nitrogen-14 in the graph above), then one half-life has passed. If two complete
half-lives have passed then 25% (or 250 atoms) of radioactive parent and 75% (or 750 atoms) of
daughter product are present.
For more information about radioactive half-life, visit TIPS P12C4 performance benchmark.
Radiometric dating has been used to determine the ages of the Earth, Moon, meteorites, ages of
fossils, including early man, timing of glaciations, ages of mineral deposits, recurrence rates of
earthquakes and volcanic eruptions, the history of reversals of Earth's magnetic field, and many
of other geological events and processes.
For additional information related to radiometric dating visit
http://www3.interscience.wiley.com:8100/legacy/college/levin/0470000201/chap_tutorial/ch01/c
hapter01-3.html and
http://wrgis.wr.usgs.gov/docs/parks/gtime/ageofearth.html#date
Radiocarbon dating
All living plants and animals have a constant ratio of carbon-14 (radioactive carbon) to carbon12 (nonradioactive carbon). After the death of an organism, the amount of radiocarbon gradually
decreases as it radioactively decays to nitrogen-14. Radiocarbon dating works by measuring the
amount of radioactivity remaining in organic materials (amount of carbon-14). From this the age
of the organic material can be determined.
For example, if carbon from a sample of wood is found to contain only half as much carbon-14
as that from a living plant, the estimated age of the old wood would be 5730 years. If only ¼ as
much carbon-14 was present, then the estimated age would be 11,460 years [2 half-lives x 5730
years/half-life].
The radiocarbon clock has become an extremely useful and efficient tool in dating the important
episodes in the recent prehistory and history of man, but because of the relatively short half-life
of carbon-14, this method can be used for dating events that have taken place only within the
past 50,000 years, and therefore is not useful for dating older geological events.
Extensive background information on radiocarbon dating can be found at
http://www.c14dating.com/k12.html
Performance Benchmark E.12.C.1
Students know how successive rock strata and fossils can be used to confirm the age, history, and
changing life forms of the Earth, including how this evidence is affected by the folding, breaking,
and uplifting of layers. E/S
Common misconceptions associate with this benchmark
1. Students have difficulty with the numerical literacy required to identify with geological
and biological concepts.
We have all been there: pose a question to students such as “How tall is that building?” and
their typical responses range from 100 feet to two miles! Now think about the human life
span of experience. We can expect to live 60 or 80, maybe even 100 years. To a high school
student of 16 years old…100 appears incredibly far away. Now consider the age of the Earth
and the geologic time scale. When talking about dates in Earth’s history such as; 10
thousand years ago the last ice age ended, or 65 million years ago to dinosaurs went extinct,
or further still the formation of the Earth 4.6 billion years ago students will have difficulty
relating to these large numbers. In the intervention strategies and resources section of this
benchmark, several activities are presented to assist students in gaining a deeper
understanding of scale and time.
For further information on this misconception and for strategies to address it, visit the Action
Bioscience website from the American Institute of Biological Sciences at
http://www.actionbioscience.org/education/lewis_lampe_lloyd.html,
Overcoming geological misconceptions article from Planet No.17, December 2006
http://www.gees.ac.uk/planet/p17/jc.pdf, and
How big is 1 billion – scale perspective activity
http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/guide/index.html
2. Students incorrectly believe that fossil evidence does NOT support evolution because
there are too many “missing links” or missing transitional fossils.
A transitional fossil is one that links a more modern organism with a more primitive
organism. A transitional fossil would have characteristics in common with both the primitive
organism and the more modern organism. Transitional fossils are often called “missing
links.” According to evolutionary theory, however, all organisms are in transition, and
therefore, a specific “missing links” may not actually exist as organisms evolve. In addition,
there are many organisms that have existed in the past for which no fossils will ever be
found, so there will always be gaps in the fossil record. This is because conditions required
for fossilization to occur are not always present when on organism dies. Many examples of
transitional fossils do exist, providing evidence that species do transition. Several examples
are listed below, with links for additional information.
For greater detail on this misconception visit
http://evolution.berkeley.edu/evosite/misconceps/IICgaps.shtml
and http://evolution.berkeley.edu/evosite/misconceps/IIDincomplete.shtml
3. Students incorrectly believe that fossils are pieces of dead animals and plants.
While in some unique circumstances actual remains of organisms become preserved (such as
saber-toothed cats in tar, mosquitoes in amber, and a mammoth in ice), the majority of fossils
are not actually pieces of dead animals and plants. They are only the impression or cast of
the original organism or plant. The actual living portion of the organism decay away but
their shape is permanently recorded in the rock as it formed.
To learn more about this misconception go to
http://education.usgs.gov/schoolyard/fossils.html
A straight forward overview of what fossils are can be found at
http://www.oum.ox.ac.uk/thezone/fossils/intro/index.htm
4. Students incorrectly think that fossils of tropical plants cannot be found in deserts.
Fossils and the rocks in which they are found record ancient environments present during the
time the rocks were deposited. The climate and topography in a particular region could have
been very different in geologic past from current day conditions. For example, during the
Paleozoic Era, Southern Nevada was a shallow sea teeming with marine life, in sharp
contrast from the desert conditions of today. Plate tectonics resulted in shifting land masses,
carrying continents from tropical regions of the planet to temperate and polar regions. As a
result of this movement, fossils can be found in areas that today could not support those types
of organisms.
For more information on this and other misconceptions go to,
http://education.usgs.gov/schoolyard/fossils.html
To see the distribution of key fossils, access the following link. Once there, “click” the
reptile image to see where fossils were found.
http://sio.ucsd.edu/voyager/earth_puzzle/
For a review of the geologic evolution of Southern Nevada (part of the virtual field trip of
Frenchman Mountain), go to
http://geoscience.unlv.edu/pub/rowland/Virtual/review.html
5. Students may incorrectly believe that radiometric dating is unreliable.
When presenting the facts about radiometric dating to students, it is important that they
understand how isotopic age dating works and that it is very accurate – typically less than 1%
error of measurement. Methods used for radiometric dating are based on sound physics, the
same physics that is at work in the students’ everyday lives. Often times students only know
about one or two isotopes (typically U-238 and/or C-14 ) and are not aware of other common
radioactive isotopes (see figure 9 for a partial list) that can be tested within the same material
yielding similar ages – supporting the reliability of radiometric dating.
For more information on this and other misconceptions, go to
http://www.ucmp.berkeley.edu/ncte/twb/misconceptions.html#radio
For an activity that models radioactive decay titled Determining Age of Rocks and Fossils,
http://www.ucmp.berkeley.edu/fosrec/McKinney.html
Performance Benchmark E.12.C.1
Students know how successive rock strata and fossils can be used to confirm the age, history, and
changing life forms of the Earth, including how this evidence is affected by the folding, breaking,
and uplifting of layers. E/S
Sample Test Questions
(Figure reference: http://www.mrsciguy.com/sciimages/pg06a.gif)
Use the rock cycle diagram above to answer question 1 and 2
1. Sandstone is a sedimentary rock which forms as a result of
a. Metamorphism
b. Solidification
c. Heat and/or pressure
d. Cementation
2. What must occur in order for an igneous rock to form?
a. Melting and solidification
b. Burial and cementation
c. Heat and pressure
d. Weathering and erosion
3. Which statement is most accurate regarding the current fossil record?
a. The fossil record is complete and contains fossils of all the types of plants and
animals that ever lived.
b. The fossil record is complete and contains fossils of all plants and animals that
ever lived
c. The fossil record is incomplete and contains fossils of a few of the plants and
animals that ever lived.
d. The fossil record is incomplete and contains most of the plants and animals that
ever lived.
Base your answers to questions 4 and 5 on the diagram below,
which shows an igneous intrusion in sedimentary rock layers
4. Which layer is the oldest?
a. A
b. B
c. D
d. E
5. Which geologic principle of relative age dating provides the reasoning for why layer C is
the youngest?
a. Principle of Superposition
b. Principle of Cross-Cutting Relations
c. Principle of Uniformitarianism
d. Principle of Original Horizontality
6. The study of the rock record suggests that
a. The period during which humans have existed is very brief compared to geologic
time.
b. Evidence of the existence of humans is present over much of the geologic past.
c. Earliest humans existed about the same time as the dinosaurs.
d. Humans first appeared just after the Earth first formed and then went extinct, only to
reappear millions of years later.
7. The half-life of carbon-14 is approximately 5700 years
A sample of wood contains 25% of the original amount of its carbon-14. Approximately
how many years ago was this wood part of a living tree?
a. 2850 years ago
b. 5700 years ago
c. 11,400 years ago
d. 22,800 years ago
Use the diagram below to answer question 8
Today
H u m a ns A pp ea r
D in o s a u rs D isa p p e a r
D in o s a u rs A p p e a r
Today
Today
D in o s a u rs D is a p p e a r
H u m an s A pp ea r
D in o s a u rs A p p e a r
H u m an s A pp ea r
D i n o sa u rs D is a p p e a r
C
(Figure reference http://www.nysedregents.org/testing/scire/es606.pdf
)
B
A
8. How many additional boxes would need to be shaded in order to accurately represent the
additional decayed material formed during the second half-life?
D in o s a u rs A p p e a r
a. 0
b. 3
L ife A p p e a rs
L ife A p p e a rs
c. 6
d. 12
L ife A p p e a rs
Earth Form s
9.
Earth Form s
Earth Form s
Today
Today
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D in o sa u rs D isa p p e a r
D in o sa u rs A p p e a r
D
E
D in o sa u rs D isa p p e a r
L ife A p p e a rs
Earth Form s
L if e (in clu d in g d in o s a u rs
a n d h u m a n s) A p p e a rs
Earth Form s
Today
referenceToday
adapted
from the geoscience
concept inventory - GCI)
H u m a ns A pp ea r
D in o s a u rs D is a p p e a r
Today(Image
D in o s a u rs D isa p p e a r
D in o s a u rs A p p e a r
H u m an s A pp ea r
D in o sa u rs D is a p p e a r
H u m an s A pp ea r
D in o s a u rs A p p e a r
Which of the graphs above most accurately represents changes in life on Earth over time?
C
B
A A
a.
b. B
c. C
D in o s a u rs A p p e a r
d. D
L ife A p p e a rs
L ife A p p e a rs
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Earth Form s
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E
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L ife A p p e a rs
Earth Form s
L if e (in clu d in g d in o s a u rs
a n d h u m a n s) A p p e a rs
Earth Form s
Use the following graph to answer questions 10-12
Radiometric dating graph showing the decay of the
radioactive parent isotope (blue) and increase in stable daughter isotope (red)
(Figure reference: http://www3.interscience.wiley.com:8100/legacy/college/levin/0470000201/chap_tutorial/ch01/chapter01-3.html)
10. What fraction of radioactive parent atoms remain after 2 half-lives?
a. 1
b. 1/2
c. 1/4
d. 1/8
11. What would happen to the half-life of this radioactive isotope if it were taken to the
below-freezing temperatures of the North Pole?
a. The half-life would decrease
b. The half-life would increase
c. The half-life would remain the same
d. The half-life would first increase, then decrease
12. The amount of initial radioactive material is doubled from 1000 to 2000 atoms. What
affect does doubling the radioactive material have on its half-life?
a. Half-life remains the same
b. Half-life doubles
c. Half-life quadruples
d. Half-life is halved
Performance Benchmark E.12.C.1
Students know how successive rock strata and fossils can be used to confirm the age, history, and
changing life forms of the Earth, including how this evidence is affected by the folding, breaking,
and uplifting of layers. E/S
Answers to Sample Test Questions
1. (d)
2. (a)
3. (c)
4. (d)
5. (b)
6. (a)
7. (c)
8. (c)
9. (d)
10. (c)
11. (c)
12. (a)
Performance Benchmark E.12.C.1
Students know how successive rock strata and fossils can be used to confirm the age, history, and
changing life forms of the Earth, including how this evidence is affected by the folding, breaking,
and uplifting of layers. E/S
Intervention Strategies and Resources
The following is a list of intervention strategies and resources that will facilitate student
understanding of this benchmark.
1. Who’s On First? A Relative Age Dating Activity
Developed by The Museum of Paleontology of The University of California, Berkeley; the
Regents of the University of California; and The Paleontological Society. In this activity,
students are introduced to sequencing and geologic time through relative dating techniques.
Students begin by categorizing cards of nonsense words, then move on to cards with pictures
of fossils. Once students begin to grasp "relative" dating, they can extend their knowledge of
geologic time by exploring radiometric dating and developing a timeline of Earth's history.
There is a teacher's guide to this activity with background information and templates to use
for teaching about relative dating. There are also objectives, materials, procedure, and
questions.
To access this activity go to http://www.ucmp.berkeley.edu/fosrec/BarBar.html.
2. Relative Dating – Telling Time Using Fossils
Developed by Oregon Public Broadcasting and PBS. This website integrates video footage
and information with lesson plans and activities to teach students about the concept of
relative dating. Students will graph a range chart for ammonites, determine the geologic age
for several rocks, and determine which rocks will be most useful for oil companies looking to
drill oil. This site contains lesson plans, student worksheets, discussion questions, and links
for more information.
The unit summary can be found at
http://www.pbs.org/americanfieldguide/teachers/fossils/fossils_sum.html
To download this PDF Lesson visit
http://www.pbs.org/americanfieldguide/teachers/fossils/fossils.pdf
3. Teaching Geoscience with Visualizations: Using Images, Animations, and Models
Effectively
This is a really great website resource developed by the Science Education Resource Center
(SERC) at Carleton College and its partners with funding from the National Science
Foundation. This site contains teaching ideas, activities, animations, models, and current
data sets related to the Geosciences.
The link to visualizations can be accessed at
http://serc.carleton.edu/NAGTWorkshops/visualization/collections.html
On the Cutting Edge search page for activities, assessments, and more is found at
http://serc.carleton.edu/NAGTWorkshops/search.html
4. Virtual Fossil Museum – Fossil Image Directory
The Virtual Fossil Museum is an educational resource that provides an ever-growing
extensive collection of fossil images. From their homepage you can access information such
as; Geologic Time, Paleobiology, Geologic History, Tree of Life, Fossils and Fossil Sites,
Evolution, and Fossil Record.
Link to Virtual Fossil Museum homepage,
http://www.fossilmuseum.net/index.htm
The fossil image directory can be directly accessed at
http://www.fossilmuseum.net/Education.htm
5. Construct Seven Paper Models that Describe Faulting of the Earth
USGS site resource that contains an instructional activity where seven 3-D paper models are
constructed by students. These models are intended to help students and others visualize the
main classes of faults and learn some of the terminology used by geologists to describe
faults. By constructing and examining these models, students will obtain a greater
appreciation of the relationship between fault displacements and the landforms that result.
To reach the teachers guide for this activity, go to
http://wrgis.wr.usgs.gov/docs/parks/deform/7faults.html
To access the print friendly models, go to
http://wrgis.wr.usgs.gov/docs/parks/deform/7modelsa.html
6. Smithsonian National Museum of Natural History – Geologic Time: The Story of a
Changing Earth
This is an interactive geologic timeline that is really well done. From the top navigation bar
users select an Eon, Era, Period, or Epoch of geologic time for exploration and are
immediately provided with an overview of that division, biologic significance of the time
(where appropriate), atmospheric information and related plate tectonic evidence.
Foundational concepts such as dating methods, Earth processes, and life processes are
accessed via navigation links on the left portion of the site.
To access this site, go to
http://paleobiology.si.edu/geotime/main/
7. Geologic Time Activity
A really great scaling activity that has students scale geologic time to a 100 yard football
field in order to gain a perspective for the various divisions of geologic time. An alternative
activity is provided for students to make a circle, pie diagram, or clock that shows the amount
of time in degrees or in percentages. Contained within this site are links to additional topics
and activities on a variety of science topics. This website is developed by Wheeling Jesuit
University and part of the NASA supported Classroom of the Future.
To access this activity, go to
http://www.cotf.edu/ete/modules/msese/earthsysflr/geo_activity.html
8. Understanding Geologic Time
Educational module (sponsored by the National Science Foundation and Berkeley University
of California) that introduces students to geologic time, the evidence for events in Earth's
history, relative and absolute dating techniques, and the significance of the geologic time
scale.
To access this educational module, go to
http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/index.html