Earth Science: Plate Tectonics Basics

Earth's Structure and Plate Tectonics

• Earth's structure has layers including the crust, mantle, outer core, and inner core.
• Major continental plates are identified on a global map, illustrating their movement.

Plate Tectonics Processes

• Subduction: Dense seafloor crust pushes under less dense continental crust, returning seafloor crust to the mantle. This process occurs at ocean trenches.
• Seafloor Spreading: New seafloor crust forms through eruptions at mid-ocean ridges where plates spread apart.

Plate Boundaries

• A map illustrates different types of plate boundaries (convergent, divergent, transform) including major plates like the North American, Eurasian, African, and Pacific plates.

Plate Tectonics and Mass Extinctions

• Climate changes, volcanic eruptions, diseases, plant evolution, environmental changes (ocean chemistry), and global marine regressions/transgressions are among the contributing causes of mass extinctions.
• Asteroid impacts have also been implicated as a cause of mass extinctions. This is not definitively the only cause.

Extinction

• Extinction is the disappearance of all individuals of a species or group of species.
• Extinction is a natural part of the evolutionary process.
• Extinction rates vary significantly throughout geological time.

Mass Extinction Events

• Specific mass extinction events, like the Ordovician, Devonian, Permian, Triassic, and K-T (Cretaceous-Paleogene) events are detailed, outlining their time periods, possible causes, and effects.

Consequences of Continental Drift

• Formation of Pangaea (a supercontinent) significantly impacted habitats, creating climate changes, and influencing evolution.

Adaptive Radiations

• Adaptive radiation occurs when organisms colonize new environments with little competition.
• The Hawaiian Islands are an example of a showcase for adaptive radiation.
• Different species characteristics can be related to distinct environments.

Evolutionary Relationships

• Evolutionary relationships between species (e.g., reptile, bird) and the importance of fossils for understanding transitional forms are illustrated. A cladistic tree shows relationships. The diagram shows a tree of life illustrating evolutionary relationships.

Microevolution

• Microevolution involves relatively small-scale changes in allele frequencies within populations or species.
• Evolution in characteristics like size, color, or resistance to factors like pesticides or diseases can be examples of microevolution.
• House sparrows in different geographic locations demonstrate microevolution, influenced by environmental factors.

Macroevolution

• Macroevolution is larger-scale evolutionary change.
• It includes the appearance of new species, significant changes in body forms, and the evolution of one species to another (e.g., dinosaurs evolving into birds.)

Darwin, Wallace and Natural Selection

• Darwin and Wallace independently proposed the theory of natural selection as a driver of evolution.
• Natural selection relates to competition for resources, survival, traits, and reproduction.

The Cretaceous Plant Problem

• Differences in plant life between the Cretaceous and the Tertiary periods are addressed.

Ocean Acidification

• Increased atmospheric carbon dioxide lowers ocean pH values.

Increasing Carbon Dioxide and Temperatures

• Increasing CO2 levels correlate with rising global temperatures. Data supports a relationship.

Biological Annihilation

• A global study identifies catastrophic declines in species populations worldwide over the past two decades. This is not related to geological time scales discussed in previous sections.
• Examples like declining populations of cheetahs, giraffes, lions, and orangutans are cited, along with causes for population decline.

Human-Caused Habitat Loss

• Human activities are shown to drive species towards extinction.
• Deforestation and habitat loss are examples of human-caused factors.
• Data shows the decline in habitat over time.

Evolutionary History of Mammals

• An ancestral mammal lineage is displayed.
• Different mammalian groups(monotremes, marsupials, placentals) and their divergence times are shown.

Microevolution and Macroevolution

• The notes differentiate between microevolution and macroevolution.
• Examples of both concepts are displayed.

K-T Impactor

• Details of the asteroid impact in the Yucatan Peninsula & its potential connection to mass extinction are examined. Size, time, and force are discussed as a possible cause of the extinction of dinosaurs.

Tiger Loss

• Data displays the shrinking historical range of the tiger (panthera tigris). Loss of habitat.