plate-tectonics_lesson-2.ppt
Transcript
Prentice Hall EARTH SCIENCE Tarbuck Lutgens Modified by: Ms. Noemie T. Marabella Enhanced Science 10 Teacher S.Y. 2023-2024 9.1 Continental Drift Rejecting the Hypothesis A New...
Prentice Hall EARTH SCIENCE Tarbuck Lutgens Modified by: Ms. Noemie T. Marabella Enhanced Science 10 Teacher S.Y. 2023-2024 9.1 Continental Drift Rejecting the Hypothesis A New Theory Emerges 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 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. Types: Oceanic - Continental Oceanic - Oceanic Continental - Continental 9.3 Actions at Plate Boundaries Convergent Boundaries 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 Andes Mountains, South America 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. Oceanic-Oceanic Convergent Boundary Aleutian Islands, Alaska 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 mountain ranges, such as the Himalayas. 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 Review Questions 1. What are the three types of boundaries? 2. What direction do plates go for each? 3. Which boundary has a subduction zone…what occurs at a subduction zone? QUESTIONS?
