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PLATE TECTONICS
NOTEBOOK CHECK
Term | Definition |
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TECTONIC PLATES | Plate Tectonics is the theory that Earth's outer crust (lithosphere) is divided into several plates that glide over the plastic-like and less ridged asthenosphere (upper mantle). |
OCEANIC CRUST | The relatively thin part of the earth's crust which underlies the ocean basins. It is geologically young compared with the continental crust and consists of basaltic rock overlain by sediments. |
CONTINENTAL CRUST | The relatively thick part of the earth's crust that forms the large landmasses. It is generally older and more complex than the oceanic crust. |
VOLCANIC ISLANDS | Volcanic islands occur in ocean basins also on or near ocean ridges (e.g., St. Paul Rocks and Ascension Island in the Atlantic Ocean) (Figure 1.3). They are large volcanoes erupted on the seafloor whose tops have emerged above sea level. |
MOUNTAIN RANGE | A line of mountains connected by high ground. |
SUBDUCTION ZONE | A geological process in which one edge of a crustal plate is forced sideways and downward into the mantle below another plate |
EARTHQUAKES | shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity |
PLATE BOUNDARIES | Plate boundaries are the edges where two plates meet. Most geologic activities, including volcanoes, earthquakes, and mountain building, take place at plate boundaries. |
TRANSFORM BOUNDARY | Plates slip sideways past each other creating earthquakes. Crust is neither created or destroyed. Many of these boundaries are found on the sea floor. The most famous transform boundary is the San Andreas fault in California. |
CONVERGENT BOUNDARY | Continental/Continental = folded mountains (Himalayas). Continental/Oceanic = volcanoes form (Cascades in Oregon and Washington) Oceanic/Oceanic = Volcanic arc of islands form(Aleutian Islands in Alaska) |
DIVERGENT BOUNDARY | Two continental crusts diverge and create a rift valley. New crust is created. Example is the Great Rift Valley in Africa Over millions of years water will eventually fill the valley. |
HIMALAYAN MOUNTAINS | The Himalayas, or Himalaya, is a mountain range in Asia separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has many of Earth's highest peaks, including the highest, Mount Everest, at the border between Nepal and China. |
SUBDUCTION BOUNDARY | The action or process in plate tectonics of the edge of one crustal plate descending below the edge of another. |
MID-ATLANTIC RIDGE | The Mid-Atlantic Ridge is a mid-ocean ridge, a divergent or constructive plate boundary located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. |
CONVERGING | Converge (colliding or coming together) |
DIVERGING | Diverge (dividing or moving apart) |
TRANSFORMING | Transform (sliding past each other) |
VOLCANO | A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust. |
SEA FLOOR SPREADING | Harry Hess discovered that magma was rising on the sea floor causing it to spread. The hot magma rising in the mantle caused the spreading on the sea floor and the large pieces of crust (tectonic plates) to move. |
RING OF FIRE | A long chain of volcanoes that surround the Pacific Ocean. One of the most geologically active area on Earth. Site of frequent earthquakes and volcanic eruptions. Caused by plate boundaries converging, diverging and transforming. |
CONVECTION CURRENTS | Transfers energy in the mantle Causes the hotter magma in the mantle to rise Causes the cooler magma in the mantle to sink |
TRENCH | Trench: very deep, elongated cavity bordering a continent or an island arc; it forms when one tectonic plate slides beneath another. |
SAN ANDRES FAULT | The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometres through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip. |
CASCADES VOLCANOES | The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles. |
RIFT VALLEY IN AFRICA | A large elongated depression with steep walls formed by the downward displacement of a block of the earth's surface between nearly parallel faults or fault systems. |