Lithosphere - Lecture notes 15 PDF

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Chapter 13-14...

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Chapter 13/14: Lithosphere  The Earth’s interior  Crust  Outermost solid layer  Makes 1% of the Earth’s volume  Basalt and felsic minerals like quartz  Mantle  Beneath the crust and surrounding the outer core  84% of volume  Outer core  Liquid shell beneath the mantle that encloses the Earth’s inner core  Inner core  Evidently solid, dense, innermost portion  Iron  Crust and mantle  Lithosphere: crust to uppermost zone of mantle (outermost 100 km of Earth)  Asthenosphere: layer of upper mantle underlying lithosphere  Very hot, weak and easily deformed  Mesosphere: part of the deep mantle  Composition  Compounds  Minerals – the building blocks of rocks  Solid, crystalline  Naturally found  Inorganic  Specific chemical compositions  Sediment: naturally-occurring material that is broken down by natural processes and is transported by the action of fluids  Bedrock: buried layer of the residual rock that has not experiences weathering and/or erosion  Rocks  Aggregate of minerals  Igneous rocks form by solidification of molten magma  Extrusive: molten rock ejected onto Earth’s surface and solidifies in open air  Intrusive: rocks that cool down and solidify beneath Earth’s surface  Sedimentary rocks form by sediment consolidation by pressure and cementation (lithification)  Formation: particles deposited by wind or water, over time builds up (compactions), cementation  Cementing agents include silica, calcium carbonate and iron oxide  Relative abundance of diff types of sed. Rocks  Sandstone: 32%  Shale: 45%  Limestone: 22%

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Metamorphic rocks formed by heating and adding pressure to existing rocks and changing structure of minerals to form new rocks  Oceanic crust mostly basaltic and denser than continental crust  Isostasy: buoyancy and floating of the Earth's less dense continental crust on the mantle  External and internal geomorphic processes  Internal  Plate tectonics  Convection: movement of mass due to changes in its density caused by gain or loss of heat  Responsible for plate movement  Plate boundaries  Divergence (seafloor spreading)  Convergence (collision, volcanic island and mountain formation)  Subduction only occurs with oceanic crust bc dense  Lateral (transform)  Diastrophism: general term referring to the deformation of Earth’s crust  2 types  Folding: more malleable crusts fold with pressure rather than breaking  Monocline (one sided slope connecting two horizontal or gently inclined strata), syncline, anticline…  Faulting: more brittle crusts break with tension rather than folding  Normal: tension stresses, pulled up  Reverse: compression, pushed up  Thrust: compression forces the upthrown block over the downthrown block  Strike-slip: movement is horizontal  Earthquake: vibration of the Earth produced by shock waves resulting from sudden displacement usually along a fault  P waves: fastest moving, alternatively compressing and relaxing the material they pass through  S waves: slower moving, producing both side-to-side and up-down motion  Common scale used to measure magnitude of earthquake: Richter scale  Volcanism  Volcano: a conical shaped landform built by the emission of lava and gases from a constricted vent in the Earth’s surface  Hot spot: volcanic area on the surface of the Earth created by a rising plume of magma  Features of volcanoes  Magma chamber: a huge, subterranean reservoir of molten rock  Central vent: the main conduit through which magma moves toward the surface  Lateral vents: found on the sides of some volcanoes where magma comes out  Crater: sits at the top of a volcano and is where the lava, gas and rock fragments/ash comes out  Lava: magma when it erupts  Tephra: fragments of rock that are ejected from the volcano  Types of volcanoes (classified by magma chemistry, explosiveness, geomorphic form)

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Basalt plateau: extensive continental deposits of basaltic volcanic rock (occur mainly in divergence zones and hot spots)  Cinder cone: small volcano made of tephra blasted out of a central vent at a high velocity, form when large amounts of gas accumulate within rising basalt magma  Composite volcanoes: made from alternate layers of viscous lava flows and tephra  Calderas: volcanoes that had violent such explosions that the central portion of the volcano was DESTROYED  Volcanic neck: volcanic activity subsides and may cool in the central vent, after a long time the overlying cone may erode to expose hardened rock inside  Dike: fin-like ridges created from magma that intruded vertical fractures  Mountain: an area of land that rises abruptly from the surrounding region  Mountain range: succession of many closely spaced mountains covering a particular region of the Earth  Mountain belts: consist of several mountain ranges parallel to each other  External  Weathering  Mass wasting  Erosion  Look to next lecture notes for actual info...