Geomorphology 07 _ Daily Class Notes.pdf

‭Geography‬ ‭Ch 01: Geomorphology‬ ‭Lecture 07: Plate Tectonics (Part 03)‬ ‭Plate:‬ ‭‬ ‭A‬ ‭plate‬ ‭is‬ ‭a‬ ‭geological‬ ‭structure‬ ‭approximately‬ ‭100‬ ‭km‬ ‭deep...

‭Geography‬ ‭Ch 01: Geomorphology‬ ‭Lecture 07: Plate Tectonics (Part 03)‬ ‭Plate:‬ ‭‬ ‭A‬ ‭plate‬ ‭is‬ ‭a‬ ‭geological‬ ‭structure‬ ‭approximately‬ ‭100‬ ‭km‬ ‭deep,‬‭constituting the uppermost part of the Earth.‬ ‭‬ ‭It‬ ‭comprises‬ ‭both‬ ‭the‬ ‭crust‬ ‭and‬ ‭the‬ ‭upper‬ ‭part‬ ‭of‬ ‭the‬ ‭upper mantle‬‭, collectively known as the‬‭lithospheric‬‭plate.‬ ‭‬ ‭These‬ ‭plates‬ ‭are‬ ‭broken,‬‭interlocked‬‭fragments‬‭that‬‭float‬ ‭over the asthenosphere.‬ ‭‬ ‭They‬ ‭are‬ ‭in‬ ‭constant‬ ‭motion,‬ ‭not‬ ‭stationary,‬ ‭and‬ ‭the‬ ‭study of this movement is known as tectonics study.‬ ‭Types of Plates:‬ ‭‬ ‭Continental Plate:‬‭A continental plate is a type of‬‭lithospheric plate‬ ‭that lies beneath a landmass. In reality, there is‬‭no completely‬ ‭land-based continental plate‬‭. For example, the Eurasian‬‭Plate has the‬ ‭largest landmass‬‭, but it‬‭also contains some water‬‭bodies.‬‭It is approximately 100 km deep. The continental‬ ‭crust is primarily composed of granite rocks.‬ ‭‬ ‭Oceanic Plate:‬‭An oceanic plate is a type of lithospheric‬‭plate that‬‭lies beneath the ocean or sea.‬‭The‬ ‭oceanic crust is primarily composed of basaltic rocks.‬ ‭‬ ‭Continental-Oceanic plate:‬‭A continental-oceanic plate‬‭is a type of lithospheric plate that includes both‬‭land‬ ‭and ocean areas‬‭. The part beneath the‬‭land consists‬‭of granite rocks,‬‭while the‬‭part beneath the ocean‬‭is‬ ‭composed of basaltic rocks.‬‭Most plates are‬‭approximately‬‭100 km deep.‬‭Examples include the‬ ‭Indo-Australian Plate, North American Plate, South American Plate, Antarctic Plate, and Eurasian Plate. The‬ ‭Pacific Plate is the largest plate.‬ ‭There are 7 Major lithospheric Plates and Approximately 20 Minor Plates:‬ ‭PW Web/App:‬‭https://smart.link/7wwosivoicgd4‬ ‭‬ ‭Major Plates:‬ ‭○‬ ‭Eurasian plate (Continental plate),‬ ‭○‬ ‭Pacific plate (oceanic plate)‬ ‭○‬ ‭African plate‬ ‭○‬ ‭Indo Australian plate‬ ‭○‬ ‭North American plate‬ ‭○‬ ‭South American plate‬ ‭○‬ ‭Antarctica plate‬ ‭‬ ‭Minor plates:‬ ‭○‬ ‭Philippine Plate‬ ‭○‬ ‭Burma plate‬ ‭○‬ ‭Caribbean plate‬ ‭○‬ ‭Nazca plate‬ ‭○‬ ‭Juan de Fuca's plate‬ ‭○‬ ‭Cocos plate‬ ‭○‬ ‭Arabian plate‬ ‭○‬ ‭Anatolian Plate‬ ‭○‬ ‭Java Plate‬ ‭Types of Plate Margins:‬ ‭‬ ‭Destructive‬‭Plate‬‭Margins:‬‭Destructive‬‭plate‬‭margins‬‭are‬‭regions‬‭where‬‭tectonic‬ ‭plates‬ ‭are‬ ‭destroyed.‬ ‭This‬ ‭occurs‬ ‭at‬ ‭convergent‬ ‭boundaries,‬ ‭where‬ ‭two‬ ‭plates‬ ‭collide,‬‭leading‬‭to‬‭one‬‭plate‬‭being‬‭forced‬‭beneath‬‭the‬‭other‬‭in‬‭a‬‭process‬‭known‬ ‭as subduction.‬ ‭‬ ‭Constructive‬‭Plate‬‭Margins:‬‭Constructive‬‭plate‬‭margins‬‭are‬‭regions‬‭where‬ ‭new‬ ‭plates‬ ‭are‬ ‭formed.‬ ‭These‬ ‭margins‬ ‭are‬ ‭typically‬ ‭found‬ ‭in‬ ‭areas‬ ‭of‬ ‭divergence,‬‭w‬‭here‬‭tectonic‬‭plates‬‭are‬‭moving‬‭apart‬‭and‬‭magma‬‭rises‬‭from‬ ‭the mantle to create new oceanic crust.‬ ‭‬ ‭Conservative‬ ‭Margins:‬ ‭Conservative‬ ‭margins‬ ‭are‬ ‭regions‬ ‭where‬ ‭tectonic‬ ‭plates‬ ‭neither‬ ‭diverge‬ ‭nor‬ ‭converge.‬ ‭Instead,‬‭the‬‭plates‬‭slide‬‭past‬‭each‬‭other‬‭along‬‭these‬‭margins‬‭without‬ ‭creating‬‭new‬‭crust‬‭or‬‭destroying‬‭existing‬‭crust.‬‭This‬‭type‬‭of‬‭boundary‬ ‭is‬ ‭known‬ ‭as‬ ‭a‬ ‭transform‬ ‭fault‬ ‭boundary.‬ ‭Conservative‬ ‭margins‬ ‭are‬ ‭associated‬ ‭with‬ ‭intense‬ ‭earthquakes,‬ ‭which‬ ‭can‬ ‭be‬ ‭disastrous,‬ ‭PW Web/App:‬‭https://smart.link/7wwosivoicgd4‬  ‭leading to significant loss of life and damage to infrastructure.‬‭Example‬‭: San Andreas‬‭Fault.‬ ‭Constructive Plate Margins or Divergent Plate Boundaries:‬ ‭‬ ‭Constructive‬ ‭plate‬ ‭margins,‬ ‭also‬ ‭known‬ ‭as‬ ‭divergent‬ ‭plate‬ ‭boundaries,‬ ‭are‬‭characterized‬‭by‬‭the‬‭formation‬‭of‬ ‭mid-ocean ridges. The stages associated with the development of mid-ocean ridges include:‬ ‭○‬ ‭Intra-continental Rifting:‬ ‭‬ ‭Intra-continental‬ ‭rifting‬ ‭begins‬‭when‬‭hot,‬‭less‬‭dense‬‭magma‬‭rises‬‭from‬‭the‬‭mantle,‬‭creating‬‭a‬‭rising‬ ‭limb‬ ‭of‬ ‭the‬ ‭convection‬ ‭cell.‬ ‭As‬ ‭this‬ ‭rising‬ ‭magma‬ ‭reaches‬ ‭the‬ ‭Earth's‬ ‭crust,‬ ‭it‬ ‭causes‬ ‭the‬ ‭crust‬ ‭to‬ ‭crack‬ ‭and‬ ‭results‬ ‭in‬ ‭domal‬ ‭uplift.‬ ‭An‬ ‭example‬ ‭of‬ ‭this‬ ‭process‬ ‭is‬ ‭the‬ ‭Ethiopian‬ ‭Highlands,‬ ‭which exhibit features of domal uplift.‬ ‭‬ ‭As‬ ‭the‬ ‭magma‬ ‭continues‬ ‭to‬ ‭interact‬ ‭with‬‭the‬‭crust,‬‭it‬‭exerts‬‭tensile‬‭forces‬‭that‬‭pull‬‭the‬‭continents‬ ‭apart.‬ ‭This‬ ‭divergence‬ ‭causes‬ ‭the‬ ‭central‬ ‭portion‬ ‭to‬ ‭subside,‬ ‭creating‬ ‭a‬ ‭rift‬ ‭valley.‬ ‭The‬ ‭process‬ ‭of‬ ‭forming‬‭this‬‭rift‬‭valley‬‭is‬‭known‬‭as‬‭faulting.‬‭An‬‭example‬‭of‬‭a‬‭rift‬‭valley‬‭formed‬‭through‬‭this‬‭process‬‭is‬ ‭the‬ ‭Great‬ ‭African‬ ‭Rift‬ ‭Valley,‬ ‭which‬ ‭stretches‬ ‭from‬‭Malawi‬‭to‬‭the‬‭Dead‬‭Sea‬‭along‬‭the‬‭Israel-Jordan‬ ‭border.‬ ‭○‬ ‭Interplate Thinning:‬ ‭‬ ‭During‬ ‭the‬ ‭subsidence‬ ‭of‬ ‭the‬ ‭crust,‬ ‭the‬ ‭two‬ ‭parts‬ ‭of‬ ‭the‬ ‭crust‬ ‭move‬ ‭apart‬‭due‬‭to‬‭divergent‬‭forces.‬ ‭Continued‬ ‭divergence‬ ‭causes‬‭further‬‭subsidence‬‭of‬‭the‬‭continental‬ ‭block.‬ ‭As‬ ‭the‬ ‭block‬ ‭reaches‬ ‭greater‬ ‭depths,‬ ‭it‬ ‭interacts‬ ‭more‬ ‭extensively‬ ‭with‬ ‭the‬ ‭magma,‬ ‭leading‬ ‭to‬ ‭additional‬ ‭melting‬‭.‬ ‭This‬ ‭process‬ ‭makes‬ ‭the‬ ‭plate‬ ‭increasingly‬ ‭thin‬‭.‬ ‭With‬ ‭the‬ ‭increased‬ ‭depth,‬ ‭water‬ ‭from‬ ‭neighboring‬ ‭seas‬ ‭or‬ ‭oceans‬ ‭can‬ ‭penetrate‬ ‭the‬ ‭area,‬‭resulting‬‭in‬‭the‬‭formation‬‭of‬‭a‬‭new‬‭narrow‬‭linear‬‭sea,‬ ‭such‬ ‭as‬‭the‬‭Red‬‭Sea.‬‭Before‬‭20‬‭million‬‭years‬‭ago,‬‭the‬‭Red‬‭Sea‬‭was‬‭part‬ ‭of‬ ‭a‬ ‭rift‬ ‭valley‬ ‭system.‬ ‭The‬ ‭Arabian‬ ‭Plate‬‭is‬‭rifting‬‭away‬‭from‬‭the‬ ‭African‬ ‭Plate‬ ‭along‬ ‭an‬ ‭active‬ ‭divergent‬ ‭ridge‬ ‭system,‬ ‭forming‬ ‭the‬ ‭Red‬‭Sea.‬‭In‬‭the‬‭future,‬‭the‬‭Great‬ ‭African Rift Valley may evolve into a long, narrow sea.‬ ‭○‬ ‭Formation of Oceanic Ridges:‬ ‭‬ ‭As‬ ‭the‬‭continental‬‭block‬‭becomes‬‭increasingly‬‭thin,‬‭magma‬ ‭can‬‭more‬‭easily‬‭intrude‬‭and‬‭emerge‬‭as‬‭lava.‬‭This‬‭process‬‭leads‬ ‭to‬‭the‬‭formation‬‭of‬‭an‬‭oceanic‬‭ridge‬‭in‬‭the‬‭center‬‭of‬‭the‬‭sea.‬ ‭The‬ ‭process‬ ‭continues,‬ ‭expanding‬ ‭the‬ ‭sea‬ ‭floor‬ ‭and‬ ‭creating‬ ‭new‬ ‭ridges.‬ ‭For‬ ‭example,‬ ‭when‬ ‭South‬ ‭America‬ ‭and‬ ‭Africa‬ ‭PW Web/App:‬‭https://smart.link/7wwosivoicgd4‬  ‭drifted‬ ‭apart,‬ ‭the‬ ‭Atlantic‬‭Ocean‬‭was‬‭formed‬‭with‬‭the‬‭Mid-Atlantic‬‭Ridge‬‭emerging‬‭in‬‭the‬‭middle.‬ ‭The lava that forms the Mid-Atlantic Ridge is‬‭basaltic in nature.‬ ‭‬ ‭At divergent boundaries, the lava that erupts is typically‬‭basaltic in composition.‬ ‭PW Web/App:‬‭https://smart.link/7wwosivoicgd4‬