Earth Science, Unit 5- The History of the Earth
Name: ____________________
The History of
the Earth
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Unit 5 Vocab:
Principle of Uniformitarianism
Relative Age
Bedding Plane
Law of superposition
Unconformity
Nonconformity
Angular unconformity
Disconformity
Law of crosscutting relationships
Half life
Paleontology
Mummification
Amber
Petrification
Trace fossils
Coprolites
Gastroliths
Index fossils
Geologic column
Era
Periods
Theory of evolution
Invertebrates
Vertebrates
Cratons
Laurasia
Gondwanaland
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Determining Relative Age
-
Geologist estimate the age of the earth to be ________________
This idea originated with the work of ________________
o 18th century Scottish physician and farmer
o Observed ______________________________________________________
o Using the _________________________________, drew conclusions based on his observations
o Theorized that the forces changing the landscape of his farm were the __________________
_______________________________________________________________________
-
Principle of uniformitarianism
o “_________________________________________________________________________
________________________________________________________________________”
o This is one of the basic foundations of the science of ___________________
o Processes are the same, but ______________________________
-
Layers of rock “_______________” are like the pages in a history book
o Can show sequence of events that took place in the past
o Relative age= ____________________________________________________
 Does not indicate __________________________________
Law of Superposition
-
To determine relative age, scientists using study _________________________________
Boundary between two layers (beds) of sedimentary rock= ___________________
Law of superposition= “____________________________________________________________
________________________________________________________________________________”
Look at figure 17-2 on p. 324. Which layer is the youngest? Oldest?
Unconformities
-
_____________________________________________________________
Indicates that for a period of time deposition stopped, rock was removed by erosion, and then
deposition resumed
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Earth Science, Unit 5- The History of the Earth
-
Name: ____________________
Three types:
Type of Unconformity
Nonconformity
Description
Sketch This:
Angular Unconformity
Disconformity
Cross Cutting Relationships
-
Law of crosscutting relationships= “__________________________________________________
_______________________________________________________________________________”
Intrusion= mass of igneous rock is formed when magma _____________________________________
If a fault cuts through an unconformity, then the fault line is _________________________________
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Determining Absolute Age
-
-
Absolute age= _________________________________________
Radioactive decay= ______________________________________________________________
o Isotope= __________________________________________________________
As atoms lose neutrons and emits energy, it changes into a ___________________________________
or an isotope of a ________________________________
Radioactive isotopes function as natural clocks
o Can measure _______________________________________________ and newly created
isotope to determine ___________________________ of the rock
Common radioactive elements:
o Uranium (U-238)
o Thorium (Th-234)
o See figure 17-7 on p. 329
Half life
-
=_________________________________________________________________________________
___________________________________________________
Ex: half-life of U-238= 4.5 billion years
o If you had 10 g of U-238, after 4.5 billion years, you would only have 5 g
o After another 4.5 bil yrs, how much U-238 would you have?
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
The Fossil Record
Paleontology= ________________________________________
-
Fossils provide clues to past geological events, climates, and evolution
o Evolution= _________________________________________________________________
Almost all fossils are found in _____________________________________
o Why might this be?
Kinds of fossils
- Classified based on how they were formed
Type of fossil
Description
Mummification
Example
Amber
Tar seep
Freezing
Petrification
Trace fossils
Imprints, molds,
and casts
Coprolites
Gastroliths
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Index fossils= ____________________________________________________________________________
-
Requirements:
1. Must be present in rocks ___________________________________________________________
2. Must have features that _________________________________________________________
3. Must have lived during a ____________________________________________ of geological time
4. Must occur in __________________________________________________ within the rock layers
-
Paleontologists can use fossils to establish the ______________________ of rock layers in which the
fossils are located
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Examining the Fossil Record
Objectives:



analyze characteristics of fossils
compare placement of fossils and determine relative ages
develop a model evolutionary tree based on the morphology and age of fossils
Background
Fossils are traces of organisms that lived in the past. When fossils are found, they are analyzed to determine
the age of the fossil. The absolute age of the fossil can be determined though radiometric dating and
determining the layer of rock in which the fossil was found. Older layers are found deeper within the earth than
newer layers.
The age and morphologies (appearances) of fossils can be used to place fossils in sequences that often show
patterns of changes that have occurred over time. This relationship can be depicted in an evolutionary tree,
also known as a phylogenetic tree.
There are two major hypotheses on how evolution takes place: gradualism and punctuated equlibrium.
Gradualism suggests that organisms evolve through a process of slow and constant change. For instance, an
organism that shows a fossil record of gradually increased size in small steps, or an organism that shows a
gradual loss of a structure. Punctuated equilibrium suggests that species evolve very rapidly and then stay the
same for a large period of time. This rapid change is attributed to a mutation in a few essential genes. The
sudden appearance of new structures could be explained by punctuated equilibrium.
Speciation
The fossil record cannot accurately determine when one species becomes another
species. However, two hypotheses regarding speciation also exist. Phyletic
speciation suggests that abrupt mutations in a few regulatory genes occur after a
species has existed for a long period of time. This mutation results in the entire
species shifting to a new species. Phyletic speciation would also relate to the
Punctuated Equilibrium hypothesis regarding evolution. Divergent speciation
suggests that a gradual accumulation of small genetic changes results in
subpopulation of a species that eventually accumulate so many changes that the
subpopulations become different species. This hypothesis would coincide with the
gradualism model of evolution. Most evolutionary biologists accept that a
combination of the two models has affected the evolution of species over time.
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Earth Science, Unit 5- The History of the Earth
Procedure:
Name: ____________________
1. The diagram you are creating requires a large space. To create your workspace, tape together 8 sheets of
standard sized paper. Use a ruler to draw the following chart on your workspace
Time Period
Began (years ago)
Fossils
( 2 1/2 inches wide)
( 2 1/2 inches wide)
(8 inches wide)
Wyomington (oldest)
995,000
(Each row here must be 4 inches tall)
Ohioian
745, 000
Nevadian
545,000
Texian
445,000
Oregonian
395,000
Coloradian
320,000
Montanian
170,000
Californian
80,000
Idahoan (the present)
30,000
2. The group of "fossils" you will work with are fictitious animals. Each fossil on your sheet is marked with a
time period. Cut out each fossil and make sure you include the time period marked below it.
3. Arrange the fossils by age. On your data chart, place each fossil next to the period from which the fossil
came from. The term "upper" means more recent and should be placed lower in the row. The term "lower"
means an earlier time period, fossils from a "lower" time period should be place toward the older time
periods. In each fossil column, you may have 3 specimens, one from the main time period, one from the
upper and one from the lower. Not all fossils are represented, illustrating the incompleteness of any fossil
record.
4. While keeping the fossils in the proper age order, arrange them by morphology
(appearance). To help you understand the morphology of the specimen, view the
diagram. Arrange the fossils using the following steps.
a. Center the oldest fossil at the top of the fossil column (toward the oldest
layer)
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
b. Through the chart, those fossils that appear to be the same (or close to the same) as the fossils
preceding them should be placed in a vertical line
c. During a certain period, the fossils will split into two branches. In other words, one fossil from that
period will show one type of change, and another fossil will show a different change. When this
happens, place the fossils side by side in the appropriate time period. From this point on you will have
two lineages?
5. Once all the fossils have been placed correctly according to time and morphology, tape or glue the fossils in
place.
Analysis
1. Give a brief description of the evolutionary changes that occurred in the organism.
2. During which time period did the fossils differentiate into two branches?
3. Explain how the chart illustrates both punctuated equilibrium and gradualism. Use specific fossils from the
chart to support your answer.
4. Making the assumption that each fossil represents a separate species. Explain how the chart illustrates
divergent and phyletic speciation. Use specific fossils from the chart to support your answer.
5. Define the following terms:



morphology
fossil
phylogenetic tree
6. Examine the fossil that was unearthed in a museum, apparently the labels and other information were lost.
Using your fossil record, determine the time period this fossil is likely from. Explain your reasoning.
7. Of the two major species that arose from the parent species, which was more successful? How do you
know?
8. For each of the “blanks” on your fossil record, draw in what the organism appearance is likely to be. Draw
this directly on your fossil record.
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Earth's history
A. Precambrian Era
1. __________________ to ___________________ years ago
2. ________________ of Earth's history”
3. Only ______________________
4. Most Precambrian rocks are ______________________________
5. Precambrian rocks
a. Most are ______________________________
b. Each continent has a "________________" of Precambrian rocks called a __________________________
c. Extensive __________________ deposits
d. Absent are ____________________________________
6. Precambrian fossils
a. Most common are ___________________________________
1. Material deposited by __________________________
2. Common about _____________________ years ago
b. Microfossils of bacteria and algae have been found in ______________________
1. ________________________________ (3.1 billion years of age)
2. ________________________________ (1.7 billion years of age)
c. Plant fossils date from the ___________________________________________
d. Animal fossils date from the __________________________________________
e. Diverse and multicelled organisms exist by the ____________________________________________
B. Paleozoic Era
1. _____________________ years ago to about _____________________ years ago
2. First life forms with ____________________________
3. Abundant _______________________________
4. Early Paleozoic history:
a. Southern continent of ______________________________ exists
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
b. North America
1. A _________________________________
2. Seas move inland and recede several times and shallow marine basins evaporate leaving ___________
_________________________________________
5. Early Paleozoic life
a. Restricted to ______
b. Vertebrates had ____________________________
c. Life consisted of several ______________________________________
1. ___________________________
2. ___________________________
3. ____________________________
d. First organisms with hard parts, such as shells - _______________________________________
6. Late Paleozoic history
a. Supercontinent of ___________________________________________
b. Several mountain belts formed during the ____________________________________________________
c. World's climate becomes very __________________, causing the ________________ of many species
7. Late Paleozoic life
a. Organisms _____________________dramatically
b. _______________ plants
c. Fishes evolve into two groups of _________________________________
1. ___________________________
2. ___________________________ which become the _________________________
d. _______________ invade the land
e. ___________________________diversify rapidly
f. Extensive ____________________________ develop
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
C. Mesozoic Era
1. ________________________ years ago to about ________________________ years ago
2. Often called the "_________________________________"
3. Mesozoic history
a. Begins with much of the world's land _____________________________________
b.____________________ invade western North America
c. Breakup of ________________________ begins forming the __________________________
d. North American plate began to override the ______________________
e. Mountains of western _______________________ began forming
4. Mesozoic life
a. Survivors of the great ____________________________________
b. ___________________________ become the dominant trees
c. _________________________ (first true terrestrial animals) readily adapt to the dry Mesozoic climate
d. Reptiles have __________________________ that can be laid on the land
e. ________________________________ dominate
f. One group of reptiles led to the_______________
g. Many reptile groups, along with many other animal groups, become ___________ at the close of the
Mesozoic
1. One hypothesis is that a ______________________________________________________
2. Another possibility is __________________________________________________
D. Cenozoic Era
1. ______________________years ago to the present
2. Often called the "_______________________________________"
3. __________________________________________________ than either the Paleozoic or the Mesozoic
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Earth Science, Unit 5- The History of the Earth
4. Cenozoic life
Name: ____________________
a. _______________________________ as the dominant land animals
b. _________________________________ (flowering plants with covered seeds) dominate the plant world
1. Strongly influenced the _____________________of both birds and mammals
2. ______________________ for both birds and mammals
c. Two groups of _______________ evolve after the reptilian extinctions at the close of the Mesozoic
1. ________________________________
2. ________________________________
d. Mammals ________________________________ and some groups become very _________________
1. e.g., Hornless rhinoceros, which stood nearly _______________________________
2. Many large animals became ________________________
e. ______________________________________evolve
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Movements of the Continents
Directions: Navigate to: http://www.scotese.com/earth.htm For each time period, describe what the continents
of the earth looked like:
Precambrian
Cambrian
Ordovician
Silurian
Devonian
Early Carboniferous
Late Carboniferous
Permian
Triassic
Jurassic
Late Jurassic
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Earth Science, Unit 5- The History of the Earth
Name: ____________________
Cretaceous
K/T extinction
Eocene
Miocene
Last Ice Age
Modern World
Future World
Future +100
Future +250
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