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Transcript
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