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Transcript
HNRS 227 Fall 2005 Chapters 14,15 Earth’s Interior, Surface, Oceans and Air presented by Prof. Geller 1, 3 November 2005 Key Points of Chapter 14 • Minerals • Rocks – Igneous, Sedimentary, Metamorphic • The Rock Cycle • Earth’s Interior – Crust, Mantle, Outer Core, Inner Core • Plate Tectonics Key Points of Chapter 15 • • • • • • • Surface Building Processes Earthquakes Mountains Volcanoes Surface Tearing Down Processes Determining Geologic Time Geologic Time Scale Telling Rocks Apart • How geologists tell apart different minerals and rocks – color, luster, texture – hardness test • scratching one against another – diamond is hardest – acid test • using weak hydrochloric acid to – streak test • form a streak across a ceramic tile Minerals (see Table 14.1) • Characteristics – naturally occurring – inorganic – definite crystalline structure • The natural resources of industry Igneous Rocks • “Rocks formed from hot molten mass of melted rock material” Sedimentary Rocks • “Rocks formed from particles or dissolved materials” • See Table 14.2 and Figure 14.11 in textbook Metamorphic Rocks • “Previously existing rocks that have been changed by heat, pressure, or hot solutions into a distinctly different rock.” • See Figure 14.12 in textbook The Rock Cycle Earth’s Interior and How We Know It Earthquakes Galore Earth’s Inside Story Crustal Rumblings Plate Tectonics • “The theory that the Earth’s crust is made of rigid plates that float on the asthenosphere.” • Consider the scientific evidence for plate tectonics and what forced scientists to accept the theory as fact Fossils Evidence for Plate Tectonics Boundaries Galore Plates are smashing Surface Building Processes • Stress – “stress is a force that tends to compress, pull apart, or deform” – different types of stress • compressive stress • tensional stress • shear stress • Strain – “the adjustment to stress” Stress and Strain Surface Building Processes • Folds – bends in layered bedrock • Anticline • Syncline \/ /\ Surface Building Processes • Faulting – formation of a crack caused by relative movement of rock on either side of a fracture • different types - normal, reverse, thrust Earthquakes • Defined as “quaking, shaking, vibrating, or upheaval of the ground” • Earthquake causes – elastic rebound theory • Intensity measure – Richter Magnitude • not linear Mountains • “elevated parts of the Earth’s crust that rise abruptly above the surrounding surface” • Causes – folding, faulting, volcanic activity Volcanoes • “hill or mountain formed by the extrusion of lava or rock fragments from magma below” • Different types – shield, cinder cone, composite (composite shown) Tear-Down Processes • Weathering – mechanical weathering – chemical weathering • Erosion – mass movement (mass wasting) – running water (floodplain, delta) – glacier – wind (deflation and abrasion) – impact cratering Development of Geologic Time • Fossilization • “Reading the Rocks” – principle of uniformity – principle of original horizontality – principle of superposition – principle of crosscutting relationships – principle of faunal succession – radiometric dating • Geologic Time Scale Geologic Time Scale