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Unit 06 23-24
Plate Tectonics
Term | Definition |
---|---|
Asthenosphere | The solid layer with plasticity in the upper mantle that is located just below the lithosphere; lithospheric plates “float†and move on this layer |
Continental Drift | The theory that continents were once connected but have drifted apart |
Convection Current | A circular movement of fluids caused by the rising of hotter, less dense fluid and the falling of cooler, denser fluid |
Convergent Boundary with Mountain Building | A major geological process; occurs when continental plates of equal density converge, creating mountains |
Convergent Boundary with Subduction | The boundary between two tectonic plates moving toward each other, resulting in volcanic activity when a denser oceanic plate subducts, or moves below, a continental plate or another oceanic plate |
Divergent Boundary | A place where two tectonic plates move away from each other |
Fossils | The mineralized remains of organisms, showing how long-dead organisms lived and how their bodies were structured |
Lithosphere | The cool, rigid, outermost layer of Earth that consists of the crust and the uppermost part of the mantle; broken into pieces or segments called plates |
Ocean Trench | Deep and narrow depression in the seafloor where the subducted plate moves into the asthenosphere |
Plate Tectonics | The theory that the crust is divided into large pieces called tectonic plates that slowly move on top of the mantle |
Seafloor Spreading | A phenomenon by which magma from Earth’s mantle comes up at the mid-ocean ridge and creates new oceanic crust |
Subduction | The process in which a denser plate is pushed downward beneath a less dense plate when plates converge |
Transform Boundary | A place where two tectonic plates slide past each other |
African Plate | A tectonic plate division of the lithosphere that includes the continental crust of Africa and the surrounding oceanic crust |
Antarctic Plate | A tectonic plate division of the lithosphere that includes the continental crust of Antarctica and the surrounding oceanic crust |
Convergent Boundary | A place where two tectonic plates move toward each other and collide |
Density of Plates | Density is the amount of matter in a given space or volume; oceanic crust is thinner but denser than continental crust. |
Divergent Boundary | A place where two tectonic plates move away from each other |
Earthquake | Major geological event that occurs when plates shift suddenly and release stored energy; a frequent occurrence along all types of plate boundaries |
Eurasian Plate | A tectonic plate division of the lithosphere including most of the landmasses of Europe and Asia |
Indo-Australian Plate | A tectonic plate division of the lithosphere that includes the continental crust of India and Australia and the surrounding oceanic crust |
Mountain Building | Major geological event that occurs when continental plates of equal density converge, resulting in mountain chains |
North American Plate | A tectonic plate division of the lithosphere that includes the continental crust of Greenland, North America, and Siberia and the surrounding oceanic crust |
Ocean Basin | A depression of Earth’s surface in which an ocean lies |
Pacific Plate | A tectonic plate division of the lithosphere that is composed entirely of oceanic crust and lies beneath the Pacific Ocean |
Plate Boundary | The place where two different plates have contact |
South American Plate | A tectonic plate that includes the continental crust of South America and the oceanic crust extending to the Mid-Atlantic Ridge |
Spreading Ridges | Ridges formed from new crustal material at diverging oceanic plate boundaries |
Subduction | The process in which a denser plate is pushed downward beneath a less dense plate when plates converge |
Tectonic Plate | Huge piece of crust that slowly moves on the upper, ductile part of the mantle |
Transform Boundary | A place where two tectonic plates slide past each other |
Volcanic Eruption | Event in which molten rock spews out from the mantle to the surface of Earth as ash, lava, and gases |