Plate Tectonics and Mass Extinctions PDF

# Plate Tectonics and Mass Extinctions ## Earth's Structure - **Crust**: The Earth's outer layer, composed of solid rock. - **Mantle**: The thickest layer, made up of hot, dense rock. - **Outer Core**: Liquid layer composed of iron and nickel. - **Inner Core**: Solid layer composed of iron and nic...

# Plate Tectonics and Mass Extinctions ## Earth's Structure - **Crust**: The Earth's outer layer, composed of solid rock. - **Mantle**: The thickest layer, made up of hot, dense rock. - **Outer Core**: Liquid layer composed of iron and nickel. - **Inner Core**: Solid layer composed of iron and nickel. ## Plate Tectonics - **Continental Plates**: Large pieces of Earth's crust that move slowly over time. - **Plate Boundaries**: The edges of the plates where they interact. - **Divergent Plate Boundaries**: Plates move apart, creating new oceanic crust at mid-ocean ridges. - **Convergent Plate Boundaries**: Plates collide, resulting in subduction zones, mountain ranges, and volcanic arcs. - **Transform Plate Boundaries**: Plates slide past each other horizontally. ## Evidence for Plate Tectonics - **Fossil Distribution**: Similar fossils found on continents now separated by oceans. - **Continental Fit**: The shapes of continents match like puzzle pieces. - **Seafloor Spreading**: New oceanic crust is formed at mid-ocean ridges, and older crust is pushed away from the ridges. - **Magnetic Anomalies**: Stripes of alternating magnetic polarity on the seafloor, indicating a pattern of crust formation and movement. ## Mass Extinctions - **Definition**: The annihilation of all individuals of a species or group of species. - **Causes**: - Climate change - Volcanic eruptions - Meteorite impacts - Sea level changes - Ocean acidification - Disease - Habitat loss - Human interaction - **Major Extinction Events**: - **Ordovician Extinction**: 445 million years ago - likely caused by rapid global cooling and falling sea levels. - **Devonian Extinction**: 340 million years ago - likely caused by asteroid impacts and rapid global cooling. - **Permian Extinction**: 250 million years ago - likely caused by volcanic activity, increased methane and CO2, and rapid global warming. - **Triassic Extinction**: 200 million years ago - likely caused by increased methane and CO2, and rapid global warming. - **Cretaceous-Paleogene Extinction**: 65 million years ago - asteroid impact, volcanic activity, and widespread fires. ## The Impact of Plate Tectonics on Evolution - **Adaptive Radiations**: Rapid diversification of species into new ecological niches. - **Example**: The Hawaiian Islands, with their diverse array of endemic species. - **Continental Drift**: - **Formation of Pangaea**: Led to a reduction in intertidal and coastal habitats and dramatic climate changes. - **Breakup of Pangaea**: Led to the isolation of continents and the development of unique species on different continents. ## Macroevolution vs. Microevolution - **Macroevolution**: Large-scale evolutionary change over vast periods of time. - **Examples**: The evolution of birds from dinosaurs, the evolution of mammals from reptiles. - **Microevolution**: Small-scale evolutionary change within a population. - **Examples**: The adaptation of house sparrows to different climates in North America, the evolution of antibiotic resistance in bacteria. ## Darwin and Wallace - **Charles Darwin and Alfred Russell Wallace**: Independently developed the theory of evolution by natural selection. - **Natural Selection**: The process by which organisms with traits better suited to their environment are more likely to survive and reproduce. ## Human Impact on Extinction - **Habitat Loss**: The primary driver of species extinction today. - **Examples**: Deforestation, agriculture, urbanization. - **Consequences**: - Loss of biodiversity - Disruption of ecosystems - Potential for cascading effects on food webs. ## Conclusion - Plate tectonics and mass extinctions are major forces shaping the history of life on Earth. - Human activities are accelerating the rate of extinction, posing a significant threat to biodiversity. - Understanding these processes is crucial for conservation efforts to protect the planet and its diverse life forms.