Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Plate Tectonics - Duplin County Schools
Document related concepts
Transcript
Plate Tectonics Theory of Plate Tectonics • Plate tectonics – Theory that the lithosphere is made up of plates that float on the asthenosphere and that the plates possibly are moved by convection currents. Types of Lithospheric • Oceanic crust • Continental crust • Lithosphere broken into plates ~30 identified Major Plates 3 types of Plate Boundaries • Divergent – plates move away • Convergent – plates collide • Transform-fault – plates grind past each other Divergent Boundary • Two plates moving away from each other; most found in the ocean; forms rifts valleys • Ex. – Mid-Atlantic Ridge Convergent Boundary • Direct collision of one plate with another • 2 types of crust; 3 types of collision 1. Oceanic – Continental Collision • More dense ocean crust subducted beneath less dense continental crust forming an oceanic trench 2. Oceanic-Oceanic Collision • More dense crust is subducted, melts, rises, forms island arc 3. Continental – Continental collision • Collision forces crust upwards forming mountains (orogeny) ex. Himalayas Transform – Fault Boundary • Plates slide past each other ex. San Andreas Fault, California Convection Currents • The transfer of heat through the movement of heated fluid; convection currents in the asthenosphere may be responsible for lithospheric plate movement. Theory of Suspect Terranes • Theory that continents are a patchwork of pieces of land (lithosphere) that have individual geologic history • Connected to form continents (blocks of terrane are scraped off oceanic crust and on to the continent as the crust is being subducted). Characteristics of Terranes • Differing rock and fossil content • Major faults at boundaries • Differing magnetic properties
