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Unit 1 Geology Notes
Name_______________
1.1 What Is Earth Science?
Overview of Earth Science
 Encompasses all sciences that seek to
understand
• __________________
• Earth's neighbors in ____________________
1.1 What Is Earth Science?
Overview of Earth Science
 Earth science includes
1. geology, the study of _____________
2. oceanography, the study of the _______________
3. _________________________, the study of the atmosphere
and the processes that produce weather
4. astronomy, the study of the ___________________
1.2 A View of Earth
Earth's Major Spheres
1. __________________
• _________ is the most prominent feature of the hydrosphere.
- Is
nearly ____ __of Earth's surface
- Holds about 97% of Earth's water
• Also includes _______ ___________found in streams,
lakes, and glaciers, as well as that found underground
1.2 A View of Earth
Earth's Major Spheres
2. Atmosphere
• Thin, tenuous blanket of _____________
• One half lies below 5.6 kilometers (3.5 miles)
3. Biosphere
• Includes all ____________
• Concentrated near the surface in a zone that extends from
the ocean floor upward for several kilometers into the
atmosphere
1.2 A View of Earth
Earth's Major Spheres
4. __________________
• Consists of the crust, mantle, and core.
- Crust—the thin, rocky ___________ layer of Earth.
- Mantle—the 2890-kilometer-thick layer of
Earth located __________ _______ _______________.
- Core—the ____________________ layer of Earth, located
beneath the mantle.
Earth’s Layered Structure
1.3 Representing Earth’s Surface
Determining Location
 Latitude and longitude are lines on the
globe that are used to determine
location.
• Latitude is distance ____________ or ________________of
the equator, measured in degrees.
• Longitude is distance ____________ or ______________of
the _____________ ________________, measured in
degrees.
Satellites and Information Technology
• Key idea: Today’s technology gives us the ability to more precisely
analyze Earth’s physical properties
• Remote sensing: collecting data about the Earth from a _________.
–
–
–
–
Weather—watch temp of air and sea, clouds, storms
Navigation—assist ships and subs exact location
Landsat—photos of land and seacoasts
VLBI—used to measure the earth
• GPS: find precise _________________ on earth used by:
–
–
–
–
–
Military
Geologists
Farmers
Drivers
Sports enthusiasts
1.4 Earth System Science
What Is a System?
 A _______________ is any size group of
interacting parts that form a complex whole.
 Closed systems are self contained
(e.g., an automobile cooling system).
 _________________ systems allow both
energy and matter to flow in and out of the
system
(e.g., a river system).
1.4 Earth System Science
Earth as a System
 Earth is a dynamic body with many
separate but highly ____________ parts
or spheres.
 Earth system science studies Earth
as a system that is composed of
numerous parts, or ________________.
1.4 Earth System Science
Earth as a System
 Sources of Energy
• ________—drives external processes such as weather,
ocean circulation and erosional processes
• Earth’s _____________—drives internal processes
including volcanoes, earthquakes and mountain
building
1.4 Earth System Science
Earth as a System
 Consists of a nearly endless array of
subsystems (e.g., hydrologic cycle)
 _______________ are part of the Earth
system.
The carbon cycle
3.1 The Rock Cycle
Rocks
 Rocks are any solid mass of mineral or
mineral-like matter occurring naturally
as part of our planet.
 Types of Rocks
1. ________________ rock is formed by the crystallization of
molten magma.
3.1 The Rock Cycle
Rocks
 Types of Rocks
2. _____________________ rock is formed from the weathered
products of preexisting rocks that have been transported,
deposited, compacted, and cemented.
3. _____________________ rock is formed by the alteration of
pre-existing rock deep within Earth (but still in the solid state)
by heat, pressure, and/or chemically active fluids.
3.1 The Rock Cycle
The Rock Cycle
 Shows the _____________________ among
the three rock types (igneous, sedimentary,
and metamorphic)
 ____________ is molten material that forms
deep beneath the Earth’s surface.
 ________ is magma that reaches the
surface.
 ___________
is a process in which rocks are
broken down by water, air, and living things.
 ____________ is weathered pieces of Earth
elements.
The Rock Cycle
3.1 The Rock Cycle
Energy That Drives the Rock Cycle
 Processes driven by heat from the Earth’s
___________ are responsible for forming
both ___________ and _____________ rock.
 ________________ and the movement of
weathered materials are external processes
powered by energy from the ___________.
 External processes produce sedimentary
rocks.
3.2 Igneous Rocks
Formation of Igneous Rocks
1. ____________ igneous rocks are
formed when magma hardens beneath
Earth’s surface.
2. _____________ igneous rocks are
formed when lava hardens.
3.2 Igneous Rocks
Classification of Igneous Rocks
 Igneous rocks can be classified based
on their composition and texture.
1. Texture
• ________________-grained texture is caused by ________
cooling resulting in ____________ crystals.
• Fine-grained texture is caused by rapid cooling resulting in
smaller, interconnected mineral grains.
Course-Grained Igneous Texture
Fine-Grained Igneous Texture
3.2 Igneous Rocks
Classification of Igneous Rocks
1. Texture (continued)
• ______________ texture is caused by very rapid cooling.
• Porphyritic texture is caused by different rates of cooling
resulting in varied sized minerals.
2. Composition
• Granitic composition rocks are made mostly
of light-colored quartz and feldspar.
Obsidian Exhibits a Glassy Texture.
Porphyritic Igneous Texture
3.2 Igneous Rocks
Classification of Igneous Rocks
2. Composition (continued)
• Basaltic composition rocks are made mostly of dark-colored
silicate minerals and plagioclase feldspar.
• Andesitic composition rocks are between granitic light-color
minerals and basaltic composition dark-colored minerals.
• Ultramafic composition rocks are made mostly from iron and
magnesium-rich minerals.
Basalt
Classification of Igneous Rocks
3.3 Sedimentary Rocks
Formation of Sedimentary Rocks
 Weathering, Erosion, and Deposition
• _______________ involves the weathering and the removal of
rock.
• ___________________ occurs when an agent of erosion—
water, wind, ice, or gravity—loses energy and drops
sediments.
3.3 Sedimentary Rocks
Formation of Sedimentary Rocks
 Compaction and Cementation
• ______________________ is a process that squeezes, or
compacts, sediments.
• _____________________ takes place when dissolved
minerals are deposited in the tiny spaces among the
sediments.
3.3 Sedimentary Rocks
Classification of Sedimentary Rocks
 Two Main Groups
1. Clastic_____________________of weathered bits of
__________ and minerals.
• Classified by particle size
• Common rocks include
- Shale (most abundant)
- Sandstone
- Conglomerate
Shale with Plant Fossils
Conglomerate
3.3 Sedimentary Rocks
Classification of Sedimentary Rocks
 Two Main Groups
2. ________________ sedimentary rocks form when dissolved
substances precipitate, or separate, from water.
• Common rocks include
-______________—most
abundant chemical rock
- microcrystalline quartz known as chert, flint,
jasper, or agate
- evaporites such as rock salt or gypsum
- coal
Fossiliferous Limestone
Classification of
Sedimentary Rocks
3.3 Sedimentary Rocks
Features of Some Sedimentary Rocks
 Features of sedimentary rocks are clues
to how and where the rocks are formed
3.4 Metamorphic Rocks
Formation of Metamorphic Rocks
 Metamorphism means “___ _________
_______________
 Most metamorphic changes occur at
elevated ____________ and _________
 Conditions for formation are found a few
_____________ below the Earth’s
surface and extend into the _________
___________
3.4 Metamorphic Rocks
Formation of Metamorphic Rocks
 ________________ metamorphism
occurs when magma moves into rock.
• Occurs near a body of _______________
• Changes are driven by a rise in temperature.
3.4 Metamorphic Rocks
Formation of Metamorphic Rocks
 Regional metamorphism results in
large-scale deformation and high-grade
metamorphism.
• Directed pressures and high temperatures occur during
______________________ _____________________.
• Produces the __________________metamorphic rock
3.4 Metamorphic Rocks
Agents of Metamorphism
 ____________
• Provides the energy needed to drive chemical reactions
 _____________
• Causes a more compact rock with greater density
Origin of Pressure in
Metamorphism
3.4 Metamorphic Rocks
Agents of Metamorphism
 Hydrothermal Solutions
• Hot water-based solutions escaping from the mass of magma
• Promote recrystallization by dissolving original minerals and
then depositing new ones
3.4 Metamorphic Rocks
Classification of Metamorphic Rocks
 Two main categories
1. ___________________ Metamorphic Rock
• Has a banded or layered appearance
2. ______________ Metamorphic Rock
• Does not have a banded texture
Classification of Metamorphic
Rocks
Gneiss Typically Displays a
Banded Appearance
Marble—A Nonfoliated
Metamorphic Rock
9.1 Continental Drift
An Idea Before Its Time
 Wegener’s ____________
___________hypothesis stated that the
continents had once been joined to form a
single supercontinent.
• Wegener proposed that the supercontinent, Pangaea, began to
break apart _______ __ __ __and form the present landmasses.
Breakup of Pangaea
9.1 Continental Drift
An Idea Before Its Time
 Evidence
• The Continental ____________
• Matching Fossils
- Fossil evidence for continental drift includes several __________
organisms found on ______________ ____________________
Matching Mountain Ranges
Glacier Evidence
9.1 Continental Drift
Rejecting the Hypothesis
 A New Theory Emerges
• Wegener could not provide an explanation of exactly ________
____________the continents move. News technology lead to
findings which then lead to
a new theory called plate tectonics.
9.2 Plate Tectonics
Earth’s Major Roles
 According to the plate tectonics theory,
the uppermost mantle, along with the
overlying crust, behaves as a strong,
________ layer. This layer is known as the
________________________.
• A plate is one of numerous rigid ____________ of the lithosphere
that move as a unit over the material of the asthenosphere.
9.2 Plate Tectonics
Types of Plate Boundaries
 Divergent boundaries (also called
____________ ______________) are the
place where two plates move apart.
 Convergent boundaries form where two
plates move ________________.
 Transform fault boundaries are margins
where two plates _________ _________
each other without the production or
destruction of the lithosphere.
Three Types of
Plate Boundaries
9.3 Actions at Plate Boundaries
Divergent Boundaries
 Oceanic Ridges and Seafloor Spreading
• Oceanic ridges are continuous elevated zones on the floor of all
major ocean basins. The __________ at the crest of ridges
represent divergent plate boundaries.
• ____________ _______________are deep faulted structures
found along the axes of divergent plate boundaries. They can
develop on the seafloor or on land.
• Seafloor spreading produces ________ oceanic
_______________.
Spreading Center
9.3 Actions at Plate Boundaries
Divergent Boundaries
 Continental Rifts
• When spreading centers develop within a continent, the landmass
may split into two
or more smaller segments, forming a ________________.
East African Rift Valley
9.3 Actions at Plate Boundaries
Convergent Boundaries
 A _____________________ zone occurs
when one oceanic plate is forced _______
into the mantle _________ a second plate.
 Oceanic-Continental
•
__________ oceanic slab sinks into the asthenosphere.
• Pockets of magma develop and rise.
• Continental volcanic arcs form in part by volcanic
activity caused by the ________________ of oceanic
lithosphere beneath a continent.
•
Examples include the Andes, ______________, and
the Sierra Nevadas.
Oceanic-Continental
Convergent Boundary
9.3 Actions at Plate Boundaries
Convergent Boundaries
 Oceanic-Oceanic
• Two oceanic slabs converge and one descends
beneath the other.
• This kind of boundary often forms volcanoes on the ocean floor.
• _______________ ______________ _________form as volcanoes
emerge from the sea.
• Examples include the Aleutian, Mariana, and Tonga islands.
Volcanic island arc—Aleutian
islands
Oceanic-Oceanic
Convergent Boundary
9.3 Actions at Plate Boundaries
Convergent Boundaries
 Continental-Continental
• When subducting plates contain continental
material, two continents collide.
• This kind of boundary can produce new
_____________
_______________, such as the ___________________.
Continental-Continental
Convergent Boundary
Collision of India and Asia
9.3 Actions at Plate Boundaries
Transform Fault Boundaries
 At a _________________ fault boundary,
plates grind past each other without
destroying the lithosphere.
 Transform faults
• Most join two segments of a mid-ocean ridge.
• At the time of formation, they roughly parallel the direction of plate
movement.
• They aid the movement of oceanic crustal material.
Transform Fault Boundary
9.4 Testing Plate Tectonics
Evidence for Plate Tectonics
 Paleomagnetism is the ________ remnant
__________ in rock bodies; this permanent
magnetization acquired by rock can be
used to determine the location of the
magnetic poles at the time the rock became
magnetized.
• __________________ polarity—when rocks show the same
magnetism as the present magnetism field
• __________________ polarity—when rocks show the opposite
magnetism as the present magnetism field
Paleomagnetism Preserved
in Lava Flows
9.4 Testing Plate Tectonics
Evidence for Plate Tectonics
 The discovery of strips of __________
______________, which lie as mirror
images across the ocean ridges, is among
the strongest evidence of seafloor
spreading.
Polarity of the Ocean Crust
9.4 Testing Plate Tectonics
Evidence for Plate Tectonics
 Earthquake Patterns
• Scientists found a close link between deep-focus
• ___________________ and ocean trenches.
• The _______________ of deep-focus earthquakes along the
oceanic ridge system was shown to be consistent with the new
theory.
9.4 Testing Plate Tectonics
Evidence for Plate Tectonics
 Ocean Drilling
• The data on the _____________ of seafloor sediment confirmed
• what the seafloor spreading hypothesis predicted.
• The youngest oceanic crust is at the ridge ___________, and the
oldest oceanic crust is at the continental __________________.
9.4 Testing Plate Tectonics
Evidence for Plate Tectonics
 Hot Spots
• A hot spot is a concentration of heat in the mantle capable of
producing magma, which rises to Earth’s surface; The Pacific
plate moves over a hot spot, producing the Hawaiian Islands.
• Hot spot __________ _______________that the plates move
over the Earth’s surface.
Hot Spot
9.5 Mechanisms of Plate Motion
Causes of Plate Motion
 Scientists generally agree that __________
occurring in the mantle is the basic driving
force for plate movement.
• Convective flow is the motion of matter resulting from changes
in temperature.
9.5 Mechanisms of Plate Motion
Causes of Plate Motion
 Slab-Pull and Ridge-Push
• Slab-pull is a mechanism that contributes to plate motion in
which cool, dense oceanic crust sinks into the mantle and “pulls”
the trailing lithosphere along. It is thought to be the primary
downward arm of convective flow in the mantle.
• Ridge-push causes oceanic lithosphere to slide down the sides of
the oceanic ridge under the pull of gravity. It may contribute to
plate motion.
9.5 Mechanisms of Plate Motion
Causes of Plate Motion
 Mantle Convection
• Mantle plumes are masses of hotter-than-normal mantle material
that ascend toward the surface, where they may lead to igneous
activity.
• The ______________________l distribution of heat within Earth
causes the thermal ____________________ in the mantle that
ultimately drives plate motion.
Mantle Convection Models
12.1 Discovering Earth’s History
Rocks Record Earth History
 Rocks record __________ __________and
changing l______ _______of the past.
 We have learned that Earth is much older
than anyone had previously imagined and
that its surface and interior have been
changed by the same geological processes
that continue today.
12.1 Discovering Earth’s History
A Brief History of Geology
 ______________________ means that the
forces and processes that we observe today
have been at work for a ________ _______
___________.
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 Relative dating tells us the
_____________ in which events occurred,
______ how long ago they occurred.
 Law of Superposition
• The law of superposition states that in an undeformed sequence
of sedimentary rocks, each bed is _____________ than the one
above it and ________________ than the one below it.
Ordering the Grand Canyon’s History
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 Principle of Original Horizontality
• The principle of original horizontality means that
_______________ of sediment are generally deposited in a
______________________ position.
Disturbed Rock Layers
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 Principle of Cross-Cutting Relationships
• The principle of cross-cutting relationships states that when a
fault cuts through rock layers, or when magma intrudes other
rocks and crystallizes, we can assume that the fault or intrusion is
__________________ than the rocks affected.
 Inclusions
• Inclusions are __________ __________________within other
rocks.
• Rocks containing inclusions are ______________________ than
the inclusions they contain.
Applying Cross-Cutting Relationships
Formation of Inclusions
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 Unconformities
• An unconformity represents a long period during which
______________ ________________, erosion _____________
previously formed rocks, and then deposition _______________.
• An angular unconformity indicates that during the pause in
deposition, a period of deformation (_____________ or
______________) and erosion occurred.
Formation of an Angular Conformity
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 types of unconformities
• A ___________________________ is when the erosional surface
separates older metamorphic or intrusive igneous rocks from
younger sedimentary rocks.
• A ___________________ is when two sedimentary rock layers are
separated by an erosional surface.
A Record of Uplift, Erosion,
and Deposition
12.1 Discovering Earth’s History
Correlation of Rock Layers
 Correlation is establishing the
___________________ of rocks of similar
age in ______________ _____________.
Correlation of Strata at Three Locations
12.2 Fossils: Evidence of Past Life
Fossil Formation
 Fossils are the remains or traces of
prehistoric life. They are important
components of sediment and sedimentary
rocks.
 The type of fossil that is formed is
_____________ _________the conditions
under which an organism died and how it
was buried.
 _____________ Remains
• Some remains of organisms—such as teeth, bones, and shells—
may not have been altered, or may have changed hardly at all
over time.
12.2 Fossils: Evidence of Past Life
Fossil Formation
 Altered Remains
• The remains of an organism are likely to be changed over time.
• Fossils often become _____________ or turned to __________.
• _____________ and __________are another common type of
fossil.
• ________________ is particularly effective in preserving leaves
and delicate animals. It occurs when an organism is buried under
fine sediment.
12.2 Fossils: Evidence of Past Life
Fossil Formation
 Indirect Evidence
• _____________ fossils are indirect evidence of prehistoric life.
Tracks
burrows
coprolites—fossilized feces
gastroliths—stomach stones for help digesting
 Conditions Favoring Preservation
• Two conditions are important for preservation: __________
__________and the possession of ____________ parts.
Types of Fossilization
12.2 Fossils: Evidence of Past Life
Fossils and Correlation
 Principle of _______ _____________states
that fossil organisms succeed one another
in a definite and determinable order.
Therefore, any time period can be
recognized by its fossil content.
 Index fossils are _________
geographically, are limited to a _______
span of geologic time, and occur in
_______ numbers.
12.2 Fossils: Evidence of Past Life
Fossil Formation
 Interpreting Environments
• Fossils can also be used to interpret and ____________ ancient
___________________.
For example, if you find ______________ fossils on top of a
mountain, that is a clue that the before it was a mountain the
rock was once under an ____________.
Overlapping Ranges of Fossils
12.3 Dating with Radioactivity
Basic Atomic Structures
 Orbiting the nucleus are _____________,
which are negative electrical charges.
 _________ ______________is the number
of protons in the atom’s nucleus.
 _________ ______________is the number
of protons plus the number of neutrons in
an atom’s nucleus.
12.3 Dating with Radioactivity
Radioactivity
 ____________________ is the
spontaneous decay of certain unstable
atomic nuclei.
Common Types of Radioactive Decay
12.3 Dating with Radioactivity
Half-Life
 A __________-___________is the amount
of time necessary for one-half of the nuclei
in a sample to _____________ to a stable
isotope.
The Half-Life Decay Curve
12.3 Dating with Radioactivity
Radiometric Dating
 Each radioactive isotope has been
_______________ at a constant rate since
the formation of the rocks in which it occurs.
 Radiometric dating is the procedure of
______________ ______ _____________
_______ of rocks and minerals that contain
radioactive isotopes.
12.3 Dating with Radioactivity
Radiometric Dating
 _____ a radioactive isotope ___________,
atoms of the ___________
______________are formed and
accumulate.
 An _______________ radiometric date can
be obtained only if the mineral remained in
a ________________ system during the
entire period since its formation.
Radioactive Isotopes Frequently
Used in Radiometric Dating
12.3 Dating with Radioactivity
Dating with Carbon-14
 Radiocarbon dating is the method for
determining age by comparing the amount
of carbon-14 to the amount of carbon-12 in
a sample.
 When an organism dies, the amount of
carbon-14 it contains gradually decreases
as it decays. By comparing the
___________ of carbon-14 to carbon-12 in
a sample, radiocarbon dates can be
determined. The half-life of C-14 is
12.3 Dating with Radioactivity
Importance of Radiometric Dating
 Radiometric dating has supported the ideas
of James Hutton, Charles Darwin, and
others who inferred that geologic time must
be _________________.
12.4 The Geologic Time Scale
Structure of the Time Scale
 Based on their interpretations of the rock
record, geologists have divided Earth’s
4.56-billion-year history into ________ that
represent specific amounts of time. Taken
together, these ________
_____________make up the geologic time
scale.
12.4 The Geologic Time Scale
Structure of the Time Scale
 ______________ represent the greatest
expanses of time. Eons are divided into
____________. Each era is subdivided into
periods. Finally, periods are divided into
smaller units called epochs.
 There are three eras within the
_______________ eon: the Paleozoic,
which means “ancient life,” the Mesozoic,
which means “middle life,” and the
Cenozoic, which means “recent life.”
12.4 The Geologic Time Scale
Structure of the Time Scale
 Each ___________ within an era is
characterized by somewhat less profound
changes in _______ forms as compared
with the changes that occur during an era.
 The periods of the ___________ era are
divided into still smaller units called
__________, during which even less
profound changes in life forms occur.
12.4 The Geologic Time Scale
Precambrian Time
 During _________________ time, there
were fewer life forms. These life forms are
more difficult to identify and the rocks have
been disturbed often.
The Geologic Time Scale
12.4 The Geologic Time Scale
____________ With the Geologic Time Scale
 A sedimentary rock may contain particles
that contain radioactive isotopes, but these
particles are ______ the _____ ______ as
the rock in which they occur.
 The _______ of a particular mineral in a
metamorphic rock does ______ necessarily
represent the ______ when the rock was
first formed. Instead, the date may indicate
when the rock was metamorphosed.
Using Radiometric Methods to
Help Date Sedimentary Rocks
13.1 Precambrian Time: Vast and Puzzling
Precambrian History
 The Precambrian encompasses immense
geological time, from Earth’s distant
beginnings ____ _______ ________ago
until the start of the Cambrian period, over 4
billion years later.
 Precambrian Rocks
• ______________ are large, relatively flat expanses of ancient
metamorphic rock within the stable continental interior.
• Much of what we know about Precambrian rocks comes from
_____________ mined from shields.
Geologic Time Scale
Remnants of Precambrian Rocks
13.1 Precambrian Time: Vast and Puzzling
Precambrian History
 Earth’s Atmosphere Evolves
• Earth’s original atmosphere was made up of gases similar to those
released in ______________ ________________today—water
vapor, carbon dioxide, nitrogen, and several trace gases, but no
oxygen.
• Later, primary plants evolved that used photosynthesis and
_______________________ ____________________.
• Oxygen began to accumulate in the atmosphere about _____
billion years ago.
13.1 Precambrian Time: Vast and Puzzling
Precambrian History
 Precambrian Fossils
• The most common Precambrian fossils are _______________
• Stromatolites are distinctively ____________ ______________
or columns of calcium carbonate. They are not the remains of
actual organisms but are the ______________ ____________
________ _______________.
• Many of these ancient fossils are preserved in chert—a hard
dense chemical sedimentary rock.
Stromatolites then and now
• Then
Now
13.2 Paleozoic Era: Life Explodes
Early Paleozoic
 Following the long Precambrian, the most
recent _______ ____________ _______ of
Earth’s history are divided into three eras:
Paleozoic, Mesozoic, and Cenozoic.
13.2 Paleozoic Era: Life Explodes
Early ______________
 Early Paleozoic History
• During the Cambrian, Ordovician, and Silurian periods, the vast
southern continent of _____________________ encompassed
five continents (South America, Africa, Australia, Antarctica, and
part of Asia).
Gondwana and the
Continental Landmasses
13.2 Paleozoic Era: Life Explodes
Early Paleozoic
 Early Paleozoic Life
• Life in early Paleozoic time was restricted to the _________.
There was no life on land yet.
Life in the Ordovician Period
13.2 Paleozoic Era: Life Explodes
Late Paleozoic
 Late Paleozoic History
• ____________________ is the continental mass that formed the
_________________ portion of Pangaea, consisting of presentday North America and Eurasia.
• By the ________ of the Paleozoic, all the continents had fused
into the supercontinent of ________________________.
Late Paleozoic Plate Movements
13.2 Paleozoic Era: Life Explodes
Late Paleozoic
 Late Paleozoic _____________
• Some _________ __ __ __, plants that had adapted to survive
at the water’s edge began to move inland, becoming
___________ plants.
• The ____________________ rapidly diversified because they
had minimal competition from other land dwellers.
(Amphibians include frogs, toads, and salamanders)
Armor-Plated Fish
Model of a Pennsylvanian
Coal Swamp
13.2 Paleozoic Era: Life Explodes
The Great Paleozoic Extinction
 The world’s __________ became very
______________, probably causing the
dramatic _____________ of many species.
 The late Paleozoic extinction was the
greatest of at least _____ ______
_____________ to occur over the past 500
million years.
13.3 Mesozoic Era: Age of Reptiles
Mesozoic Era
 ____________________ were landdwelling reptiles that thrived during the
Mesozoic History
era.
 Mesozoic
• A major event of the Mesozoic era was the ______________ ____
_______________.
13.3 Mesozoic Era: Age of Reptiles
Mesozoic Era
 Mesozoic Life
• ______________________ are seed-bearing plants that do not
depend on free-standing water for fertilization. Gymnosperms
are plants that have cones.
• The gymnosperms quickly became the dominant plants of the
Mesozoic era.
Gymnosperms
Canadian Rockies Were Formed Throughout
the Cretaceous Period
13.3 Mesozoic Era: Age of Reptiles
Mesozoic Era
 The Shelled Egg
• Unlike amphibians, reptiles have __________-covered eggs that
can be laid on the ____________.
• The elimination of a water-dwelling stage (like the
_____________ stage in frogs) was an important evolutionary
step.
13.3 Mesozoic Era: Age of Reptiles
Mesozoic Era
 Reptiles Dominate
• With the perfection of the shelled egg, reptiles quickly became the
__________________ ______________ ________________.
• At the end of the Mesozoic era, many reptile groups became
___________________.
The Flying Reptile Pteranodon
13.4 Cenozoic Era: Age of Mammals
Cenozoic North America
 The Cenozoic era is divided into ________
periods of very unequal duration, the
Tertiary period and the Quaternary period.
 Plate interactions during the Cenozoic era
caused many events of _______________
building, volcanism, and earthquakes in the
West.
13.4 Cenozoic Era: Age of Mammals
Cenozoic Life
 Mammals—animals that ______ _______
___________ and maintain a steady body
temperature— _____________ reptiles as
the dominant land animals in the Cenozoic
era.
 Angiosperms—______________ plants
with covered seeds—___________
gymnosperms as the dominant land plants.
13.4 Cenozoic Era: Age of Mammals
Cenozoic Life
 Mammals Replace Reptiles
• Adaptations like being warm blooded, developing insulating body
hair, and having more efficient heart and lungs allow mammals
to lead more active lives than reptiles.
Fossils from La Brea Tar Pits
13.4 Cenozoic Era: Age of Mammals
Cenozoic Life
 Large Mammals and Extinction
• In North America, the ___________ and ____________, both
huge relatives of the elephant, became extinct. In addition, sabertoothed cats, giant beavers, large ground sloths, horses, camels,
giant bison, and others died out on the North American continent.
• The reason for this recent wave of extinctions puzzles scientists. 3
probable causes are: ____________ killed them off,
______________ change (end of ice age) and
______________________—humans and domesticated animals
contained germs that jumped to the wild species.
Wooly mammoths
Mastodons