Download Sedimentary rock

Warm up January 10, 2012
• 1. What is the Carbon Cycle?
• 2. What are the 4 main branches of Earth
Science?
• 3. What are the 4 spheres?
• 4. What does a topographic map show us?
Chapter
1
Introduction to
Earth Science
1.1 What Is Earth Science?
Overview of Earth Science
 Encompasses all sciences that seek to
understand
• Earth
• Earth's neighbors in space
1.1 What Is Earth Science?
Overview of Earth Science
 Earth science includes
1. geology, the study of Earth
2. oceanography, the study of the ocean
3. meteorology, the study of the atmosphere and the processes
that produce weather
4. astronomy, the study of the universe
1.2 A View of Earth
Earth's Major Spheres
1. Hydrosphere
• Ocean is the most prominent feature of the hydrosphere.
- Is
nearly 71% of Earth's surface
- Holds about 97% of Earth's water
• Also includes fresh water 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 air
• One half lies below 5.6 kilometers (3.5 miles)
3. Biosphere
• Includes all life
• 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. Geosphere
• Based on compositional differences, it consists of the crust,
mantle, and core.
- Crust—the thin, rocky outer layer of Earth.
- Mantle—the 2890-kilometer-thick layer of
Earth located below the crust.
- Core—the innermost 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 north or south of the equator, measured in
degrees.
• Longitude is distance east or west of the prime meridian,
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 distance.
–
–
–
–
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 locations on earth
–
–
–
–
–
Military
Geologists
Farmers
Drivers
Sports enthusiasts
1.4 Earth System Science
What Is a System?
 A system is any size group of interacting
parts that form a complex whole.
 Closed systems are self contained
(e.g., an automobile cooling system).
 Open 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 interacting parts
or spheres.
 Earth system science studies Earth
as a system that is composed of
numerous parts, or subsystems.
1.4 Earth System Science
Earth as a System
 Sources of Energy
• Sun—drives external processes such as weather, ocean
circulation and erosional processes
• Earth’s interior—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)
 Humans are part of the Earth system.
The carbon cycle
Warm up
January 11, 2012
• What is an igneous rock?
• What is a Sedimentary rock?
• What is a Metamorphic rock?
Chapter
3
Rocks
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. Igneous rock is formed by the crystallization of molten
magma.
3.1 The Rock Cycle
Rocks
 Types of Rocks
2. Sedimentary rock is formed from the weathered products of
preexisting rocks that have been transported, deposited,
compacted, and cemented.
3. Metamorphic 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 interrelationships among the three
rock types (igneous, sedimentary, and
metamorphic)
 Magma is molten material that forms deep
beneath the Earth’s surface.
 Lava is magma that reaches the surface.
 Weathering is a process in which rocks are
broken down by water, air, and living things.
 Sediment 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
interior are responsible for forming both
igneous rock and metamorphic rock.
 Weathering and the movement of weathered
materials are external processes powered by
energy from the sun.
 External processes produce sedimentary
rocks.
3.2 Igneous Rocks
Formation of Igneous Rocks
1. Intrusive igneous rocks are formed
when magma hardens beneath Earth’s
surface.
2. Extrusive 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
• Coarse-grained texture is caused by slow cooling resulting in
larger 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)
• Glassy 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
• Erosion involves the weathering and the removal of rock.
• Deposition 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
• Compaction is a process that squeezes, or compacts,
sediments.
• Cementation 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 sedimentary rocks are composed
of weathered bits of rocks 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. Chemical sedimentary rocks form when dissolved
substances precipitate, or separate, from water.
• Common rocks include
- limestone—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
Warm up 3-31-11
• What is the difference between intrusive
igneous and extrusive igneous rock?
• How does the differences on where rock form
effect the type of texture it has?
• Explain both compaction and cementation:
Warm Up 4-4-2011
• What is the difference between compaction
and cementation?
• Define Intrusive and Extrusive igneous rock:
• Explain texture differences between the two
types of rocks:
Warm Up April 4th 2011
• What are 2 types of Sedimentary Rock?
• What are the Two Agents of Metamorphism
for Rock
3.4 Metamorphic Rocks
Formation of Metamorphic Rocks
 Metamorphism means “to change
form.”
 Most metamorphic changes occur at
elevated temperatures and pressures.
 Conditions for formation are found a few
kilometers below the Earth’s surface
and extend into the upper mantle.
3.4 Metamorphic Rocks
Formation of Metamorphic Rocks
 Contact metamorphism occurs when
magma moves into rock.
• Occurs near a body of magma
• 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
mountain building.
• Produces the most metamorphic rock
3.4 Metamorphic Rocks
Agents of Metamorphism
 Heat
• Provides the energy needed to drive chemical reactions
 Pressure
• 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. Foliated Metamorphic Rock
• Has a banded or layered appearance
2. Nonfoliated Metamorphic Rock
• Does not have a banded texture
Classification of Metamorphic
Rocks
Gneiss Typically Displays a
Banded Appearance
Marble—A Nonfoliated
Metamorphic Rock
Warm up April 5th 2011
• What is Continental Drift?
• What are 3 types of plate boundaries?
• What is some evidence that proves
Continental Drift occurred?
Chapter
9
Plate Tectonics
9.1 Continental Drift
An Idea Before Its Time
 Wegener’s continental drift hypothesis
stated that the continents had once been
joined to form a single supercontinent.
• Wegener proposed that the supercontinent, Pangaea, began to
break apart 200 million years ago and form the present
landmasses.
Breakup of Pangaea
9.1 Continental Drift
An Idea Before Its Time
 Evidence
1. The Continental Puzzle. The coastlines of continents match.
2. The mountain ranges match.
3. Matching Fossils
- Fossil evidence for continental drift includes several fossil
organisms found on different
landmasses.
More evidence
Glaciers were located on parts of continents
that are now in or near the tropics (they must
have moved)
South America, India, Africa, Austalia (see map)
Matching Mountain Ranges
9.1 Continental Drift
Rejecting the Hypothesis
 A New Theory Emerges
• Wegener could not provide an explanation of exactly what made
the continents move.
New 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, rigid
layer. This layer is known as the
lithosphere.
• A plate is one of numerous rigid sections 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
spreading centers) are the place where two
plates move apart.
 Convergent boundaries form where two
plates move together.
 Transform fault boundaries are margins
where two plates grind past each other
without the production or destruction of the
lithosphere.
Three Types of
Plate Boundaries
Warm Up April 6th
• What is a Transform Fault?
• Describe what happens at a Convergent
Boundary. (Continental/Continental)
• What two spheres break up the Geo Sphere?
• Describe a Divergent Boundary?
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 rifts at the crest of ridges represent
divergent plate boundaries.
• Rift valleys are deep faulted structures found along the axes of
divergent plate boundaries. They can develop on the seafloor or
on land.
• Seafloor spreading produces new oceanic lithosphere.
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 rift.
East African Rift Valley
9.3 Actions at Plate Boundaries
Convergent Boundaries
 A subduction zone occurs when one
oceanic plate is forced down into the
mantle beneath a second plate.
 Oceanic-Continental
•
Denser oceanic slab sinks into the asthenosphere.
• Pockets of magma develop and rise.
• Continental volcanic arcs form in part by volcanic
activity caused by the subduction of oceanic
lithosphere beneath a continent.
•
Examples include the Andes, Cascades, 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.
• Volcanic island arcs 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 Himalayas.
mountain ranges,
Continental-Continental
Convergent Boundary
Collision of India and Asia
9.3 Actions at Plate Boundaries
Transform Fault Boundaries
 At a transform 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 natural remnant
magnetism 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.
• Normal polarity—when rocks show the same magnetism as the
present magnetism field
• Reverse 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 alternating
polarity, 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
 Ocean Drilling
• The data on the ages of seafloor sediment confirmed what the
seafloor spreading hypothesis predicted.
• The youngest oceanic crust is at the ridge crest, and the oldest
oceanic crust is at the continental edges.
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 evidence supports that the plates move over the Earth’s
surface.
Hot Spot
Warm up April 7th
1. What is a subduction zone?
2. Explain Paleomagnetism:
3.Explain Convection Currents?
9.5 Mechanisms of Plate Motion
Causes of Plate Motion
 Scientists generally agree that convection
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 unequal distribution of heat within Earth causes the thermal
convection in the mantle that ultimately drives plate motion.
Mantle Convection Models
Chapter
12
Geologic Time
12.1 Discovering Earth’s History
Rocks Record Earth History
 Rocks record geological events and
changing life forms 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
 Uniformitarianism means that the forces
and processes that we observe today have
been at work for a very long time.
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 Relative dating tells us the sequence in
which events occurred, not how long ago
they occurred.
 Law of Superposition
• The law of superposition states that in an undeformed sequence
of sedimentary rocks, each bed is older than the one above it and
younger 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 layers of
sediment are generally deposited in a horizontal 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
younger than the rocks affected.
 Inclusions
• Inclusions are rocks contained within other rocks.
• Rocks containing inclusions are younger 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
deposition stopped, erosion removed previously formed rocks,
and then deposition resumed.
• An angular unconformity indicates that during the pause in
deposition, a period of deformation (folding or tilting) and erosion
occurred.
Formation of an Angular Conformity
12.1 Discovering Earth’s History
Relative Dating—Key Principles
 Unconformities
• A nonconformity is when the erosional surface separates older
metamorphic or intrusive igneous rocks from younger
sedimentary rocks.
• A disconformity 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 equivalence
of rocks of similar age in different areas.
Warm up April 13
• What is an unconformity?
• Explain Relative dating?
• What is the law of superposition?
• What is the Principle of Original Horizontality
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
determined by the conditions under which
an organism died and how it was buried.
 Unaltered 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 petrified or turned to stone.
• Molds and casts are another common type of fossil.
• Carbonization 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
• Trace fossils are indirect evidence of prehistoric life.
 Conditions Favoring Preservation
• Two conditions are important for preservation: rapid burial and the
possession of hard parts.
Types of Fossilization
12.2 Fossils: Evidence of Past Life
Fossils and Correlation
 The principle of fossil succession 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 widespread
geographically, are limited to a short span of
geologic time, and occur in large numbers.
12.2 Fossils: Evidence of Past Life
Fossil Formation
 Interpreting Environments
• Fossils can also be used to interpret and describe ancient
environments.
For example, if you find marine fossils on top of a mountain, that is
a clue that the before it was a mountain the rock was once under
an ocean.
Overlapping Ranges of Fossils
12.3 Dating with Radioactivity
Basic Atomic Structures
 Orbiting the nucleus are electrons, which
are negative electrical charges.
 Atomic number is the number of protons in
the atom’s nucleus.
 Mass number is the number of protons plus
the number of neutrons in an atom’s
nucleus.
12.3 Dating with Radioactivity
Radioactivity
 Radioactivity is the spontaneous decay of
certain unstable atomic nuclei.
Common Types of Radioactive Decay
12.3 Dating with Radioactivity
Half-Life
 A half-life is the amount of time necessary
for one-half of the nuclei in a sample to
decay to a stable isotope.
The Half-Life Decay Curve
12.3 Dating with Radioactivity
Radiometric Dating
 Each radioactive isotope has been
decaying at a constant rate since the
formation of the rocks in which it occurs.
 Radiometric dating is the procedure of
calculating the absolute ages of rocks and
minerals that contain radioactive isotopes.
12.3 Dating with Radioactivity
Radiometric Dating
 As a radioactive isotope decays, atoms of
the daughter product are formed and
accumulate.
 An accurate radiometric date can be
obtained only if the mineral remained in a
closed system during the entire period
since its formation.
Warm up April 18th
• 1. Explain what the lab showed us from Last
week Thursday?
• 2. Explain Radioactivity?
• 3. What is an index fossil?
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 ratio of
carbon-14 to carbon-12 in a sample,
radiocarbon dates can be determined. The
half-life of C-14 is 5,730 years.
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 immense.
Warm up 4-14-11
• What are the 3 type of plate boundaries?
• What are the 4 different segments of time we
use to brake up the geologic record?
• Explain Radio Carbon Dating.
• What is Half Life?
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 units that
represent specific amounts of time. Taken
together, these time spans make up the
geologic time scale.
12.4 The Geologic Time Scale
Structure of the Time Scale
 Eons represent the greatest expanses of
time. Eons are divided into eras. Each era
is subdivided into periods. Finally, periods
are divided into smaller units called epochs.
 There are three eras within the
Phanerozoic 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 period within an era is characterized
by somewhat less profound changes in life
forms as compared with the changes that
occur during an era.
 The periods of the Cenozoic era are divided
into still smaller units called epochs, during
which even less profound changes in life
forms occur.
12.4 The Geologic Time Scale
Precambrian Time
 During Precambrian 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
Difficulties With the Geologic Time Scale
 A sedimentary rock may contain particles
that contain radioactive isotopes, but these
particles are not the same age as the rock
in which they occur.
 The age of a particular mineral in a
metamorphic rock does not necessarily
represent the time when the rock was first
formed. Instead, the date may indicate
when the rock was metamorphosed.
Using Radiometric Methods to
Help Date Sedimentary Rocks
Chapter
13
Earth’s History
13.1 Precambrian Time: Vast and Puzzling
Precambrian History
 The Precambrian encompasses immense
geological time, from Earth’s distant
beginnings 4.56 billion years ago until the
start of the Cambrian period, over 4 billion
years later.
 Precambrian Rocks
• Shields are large, relatively flat expanses of ancient metamorphic
rock within the stable continental interior.
• Much of what we know about Precambrian rocks comes from
ores 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 volcanic eruptions today—water vapor, carbon
dioxide, nitrogen, and several trace gases, but no oxygen.
• Later, primary plants evolved that used photosynthesis and
released oxygen.
• Oxygen began to accumulate in the atmosphere about 2.5 billion
years ago.
13.1 Precambrian Time: Vast and Puzzling
Precambrian History
 Precambrian Fossils
• The most common Precambrian fossils are stromatolites.
• Stromatolites are distinctively layered mounds or columns of
calcium carbonate. They are not the remains of actual organisms
but are the material deposited by algae.
• 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 540 million years of Earth’s history
are divided into three eras: Paleozoic,
Mesozoic, and Cenozoic.
13.2 Paleozoic Era: Life Explodes
Early Paleozoic
 Early Paleozoic History
• During the Cambrian, Ordovician, and Silurian periods, the vast
southern continent of Gondwana 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 seas.
Life in the Ordovician Period
13.2 Paleozoic Era: Life Explodes
Late Paleozoic
 Late Paleozoic History
• Laurasia is the continental mass that formed the northern portion
of Pangaea, consisting of present-day North America and
Eurasia.
• By the end of the Paleozoic, all the continents had fused into the
supercontinent of Pangaea.
Late Paleozoic Plate Movements
13.2 Paleozoic Era: Life Explodes
Late Paleozoic
 Late Paleozoic Life
• Some 400 million years ago, plants that had adapted to survive
at the water’s edge began to move inland, becoming land
plants.
• The amphibians rapidly diversified because they had minimal
competition from other land dwellers.
Armor-Plated Fish
Model of a Pennsylvanian
Coal Swamp
13.2 Paleozoic Era: Life Explodes
The Great Paleozoic Extinction
 The world’s climate became very seasonal,
probably causing the dramatic extinction of
many species.
 The late Paleozoic extinction was the
greatest of at least five mass extinctions to
occur over the past 500 million years.
13.3 Mesozoic Era: Age of Reptiles
Mesozoic Era
 Dinosaurs were land-dwelling reptiles that
thrived during the Mesozoic era.
 Mesozoic History
• A major event of the Mesozoic era was the breakup of Pangaea.
13.3 Mesozoic Era: Age of Reptiles
Mesozoic Era
 Mesozoic Life
• Gymnosperms 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 shell-covered eggs that can be
laid on the land.
• The elimination of a water-dwelling stage (like the tadpole 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
dominant land animals.
• At the end of the Mesozoic era, many reptile groups became
extinct.
The Flying Reptile Pteranodon
13.4 Cenozoic Era: Age of Mammals
Cenozoic North America
 The Cenozoic era is divided into two
periods of very unequal duration, the
Tertiary period and the Quaternary period.
 Plate interactions during the Cenozoic era
caused many events of mountain building,
volcanism, and earthquakes in the West.
13.4 Cenozoic Era: Age of Mammals
Cenozoic Life
 Mammals—animals that bear live young
and maintain a steady body temperature—
replaced reptiles as the dominant land
animals in the Cenozoic era.
 Angiosperms—flowering plants with
covered seeds—replaced 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 mastodon and mammoth, 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: humans killed them off, climate change
(end of ice age) and hyperdisease—humans and domesticated
animals contained germs that jumped to the wild species.
Wooly mammoths
Mastodons
Warm up 2/8/11
• What are the 4 spheres
• 4 Major branches of earth Science
• Draw the boat on water example
• Three types of rocks