16 Questions
What is the approximate thickness of tectonic plates?
100-200 km
What is the primary driver of tectonic plate movement?
Convection currents in the Earth's mantle
What type of plate boundary is characterized by the creation of new crust?
Divergent boundaries
What process occurs when denser oceanic crust is pushed beneath lighter continental crust?
Subduction
What is the term for the movement of continents across the Earth's surface?
Continental drift
What is one of the ways in which tectonic plates influence the Earth's surface?
Shaping the Earth's surface, creating mountains, volcanoes, and oceanic trenches
Match the following features with the characteristics of mid-ocean ridges:
Elevated topography = Characteristic of mid-ocean ridges Old ages of rocks = Not a characteristic of mid-ocean ridges Volcanic activity = Characteristic of mid-ocean ridges Low heat flow = Not a characteristic of mid-ocean ridges
Match the following types of evidence with the process they support:
Magnetic striping = Seafloor spreading Fossil evidence = Continental drift Paleomagnetism = Seafloor spreading Continental fit = Continental drift
Match the following fossils with the continents where they were found:
Mesosaurus = Africa and South America Lystrosaurus = Africa and Antarctica Dinosaurs = Not mentioned in the text Trilobites = Not mentioned in the text
Match the following concepts with the process they describe:
Seafloor spreading = Creation of new oceanic crust Continental drift = Movement of continents over time Mid-ocean ridges = Zones of extension Paleomagnetism = Fossil magnetism in rocks
Match the following statements with the type of evidence they describe:
Rocks on either side of mid-ocean ridges increase in age with distance from the ridge. = Age of oceanic crust The continents fit together like a jigsaw puzzle. = Continental fit Fossils of the same age and species found on different continents. = Fossil evidence Alternating magnetic polarities on either side of mid-ocean ridges. = Magnetic striping
Match the following characteristics with the type of plate boundary they describe:
Creation of new crust = Divergent boundary Destruction of crust = Convergent boundary Transform faulting = Transform boundary No characteristic mentioned = Unknown boundary
Match the following features with the process that occurs at mid-ocean ridges:
Elevated topography = Zone of extension Volcanic activity = Zone of extension High heat flow = Zone of extension Destruction of crust = Not a process at mid-ocean ridges
Match the following types of evidence with the theory they support:
Magnetic striping = Seafloor spreading Fossil evidence = Continental drift Paleomagnetism = Seafloor spreading Continental fit = Continental drift
Match the following processes with the type of plate boundary they occur at:
Creation of new crust = Divergent boundary Destruction of crust = Convergent boundary Transform faulting = Transform boundary No process mentioned = Unknown boundary
Match the following observations with the conclusion they support:
Fossils of the same age and species found on different continents. = Continents have moved over time The continents fit together like a jigsaw puzzle. = Continents have moved over time Alternating magnetic polarities on either side of mid-ocean ridges. = Seafloor spreading occurs No observation mentioned = No conclusion mentioned
Study Notes
What are Tectonic Plates?
- Tectonic plates are large, rigid slabs of the Earth's lithosphere (outer layer)
- They fit together like a jigsaw puzzle, covering the entire surface of the Earth
- There are 7 major plates and several smaller ones
Characteristics of Tectonic Plates
- Thickness: 100-200 km
- Composition: oceanic crust (dense, basaltic rock) and continental crust (less dense, granitic rock)
- Movement: slow, about 2-10 cm/yr, driven by convection currents in the Earth's mantle
Types of Plate Boundaries
- Divergent boundaries: plates move apart, new crust forms (e.g., mid-ocean ridges)
- Convergent boundaries: plates move towards each other, resulting in subduction, collision, or mountain building
- Transform boundaries: plates slide past each other horizontally, without creating or destroying crust
Plate Tectonic Processes
- Seafloor spreading: new oceanic crust is created at mid-ocean ridges, pushing older crust apart
- Subduction: denser oceanic crust is pushed beneath lighter continental crust
- Continental drift: continents move across the Earth's surface, resulting in changes in climate, geography, and life
Importance of Tectonic Plates
- Shape the Earth's surface, creating mountains, volcanoes, and oceanic trenches
- Influence global climate, ocean currents, and geological events (e.g., earthquakes, volcanic eruptions)
- Affect the distribution of natural resources, such as minerals and fossil fuels
What are Tectonic Plates?
- Tectonic plates are large, rigid slabs of the Earth's lithosphere, covering the entire surface of the Earth like a jigsaw puzzle
- There are 7 major plates and several smaller ones
Characteristics of Tectonic Plates
- Thickness: 100-200 km
- Composition: oceanic crust (dense, basaltic rock) and continental crust (less dense, granitic rock)
- Movement: slow, about 2-10 cm/yr, driven by convection currents in the Earth's mantle
Types of Plate Boundaries
- Divergent boundaries: plates move apart, new crust forms (e.g., mid-ocean ridges)
- Convergent boundaries: plates move towards each other, resulting in subduction, collision, or mountain building
- Transform boundaries: plates slide past each other horizontally, without creating or destroying crust
Plate Tectonic Processes
- Seafloor spreading: new oceanic crust is created at mid-ocean ridges, pushing older crust apart
- Subduction: denser oceanic crust is pushed beneath lighter continental crust
- Continental drift: continents move across the Earth's surface, resulting in changes in climate, geography, and life
Importance of Tectonic Plates
- Shape the Earth's surface, creating mountains, volcanoes, and oceanic trenches
- Influence global climate, ocean currents, and geological events (e.g., earthquakes, volcanic eruptions)
- Affect the distribution of natural resources, such as minerals and fossil fuels
Evidence of Tectonic Plates
- Seafloor spreading theory proposes that new oceanic crust is created at mid-ocean ridges and destroyed at deep-sea trenches.
- Evidence for seafloor spreading includes:
- Magnetic striping: alternating magnetic polarities on either side of mid-ocean ridges, indicating reversals in Earth's magnetic field.
- Age of oceanic crust: rocks on either side of mid-ocean ridges increase in age with distance from the ridge.
- Paleomagnetism: fossil magnetism in rocks indicates the position of the Earth's magnetic poles in the past.
Mid-ocean Ridges
- Long mountain ranges that run through the center of the oceans.
- Characteristics:
- Elevated topography
- Volcanic activity
- High heat flow
- Young ages of rocks
- Mid-ocean ridges are zones of extension, where tectonic plates are moving apart and new crust is being created.
Fossil Evidence
- Fossils of the same age and species found on different continents, indicating that these continents were once connected.
- Examples:
- Mesosaurus fossils found in both Africa and South America.
- Lystrosaurus fossils found in both Africa and Antarctica.
- Fossil evidence suggests that continents have moved over time and were once connected in a supercontinent.
Continental Fit
- The observation that the continents fit together like a jigsaw puzzle.
- The boundaries of the continents, such as the eastern coast of South America and the western coast of Africa, have a similar shape and fit together perfectly.
- The fit of the continents is strong evidence for continental drift and plate tectonics.
Learn about the characteristics of tectonic plates, including their thickness, composition, and movement. Understand how they fit together and cover the Earth's surface.
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