Chapter 16 Mountains and Plate Tectonics what s the connection? Mountain Building Most crustal deformation occurs along plate margins. S.2 Active Margin Passive Margin Mountain Building Factors Affecting Deformation includes temperature, confining pressure, rock type, and time. Deformation - all changes in the original shape and/or size of a rock body. Stress is the force per unit area acting on a solid. Strain is the change in shape or volume of a body of rock as a result of stress. S.3 1
Rock Deformation Types of Stress Types of Stress The three types of stresses are: tensional stress (pulling apart) compressional stress (pushing together) shearing stress (tearing apart) tensional stress compressional stress shearing stress S.4 Rock Deformation Anticlines and Synclines Folds Anticlines Anticlines are most commonly formed by the upfolding, or arching, of rock layers. Synclines Synclines are linear downfolds in sedimentary strata. Monoclines Monoclines are large step-like folds in otherwise horizontal sedimentary strata. syncline anticline S.5a S.5b 2
Monoclines Rock Deformation monocline Faults Normal Faults Normal faults occur when the hanging wall block moves down relative to the footwall block. Reverse Faults and Thrust Faults Reverse faults are faults in which the hanging wall block moves up relative to the footwall block. Thrust faults are reverse faults with dips less than 45 o. S.5c S.6 Rock Deformation Four Types of Faults Faults Strike-Slip Fault Strike-slip faults are faults in which the movement is horizontal and parallel to the trend, or strike, of the fault surface. Joints Joints are fractures along which no appreciable movement has occurred. S.7 S.8a 3
Joints Mountains are classified by the dominant processes that have formed them. Orogenesis or Orogeny is the collection of processes that result in the forming of mountains. S.8b S.9a A. Fold & Thrust Mountains B. Dome Mountains A. Folded Mountains Mountains that are formed primarily by folding are called folded mountains. C. Fault Block Mountains D. Volcanic Mountains (see Chapter 14 notes) S.9b S.10a 4
Folded Mountains B. Domes and Basins When upwarping produces a circular or elongated structure, the feature is called a dome. Uplifted mountains are circular or elongated structures formed by uplifting of the underlying basement rock. S.10b S.10c Domed Mountains C. Fault-Block Mountains Large-scale normal faults are associated with structures called fault-block mountains. Fault-block mountains are formed as large blocks of crust are uplifted and tilted along normal faults. Grabens are formed by the downward displacement of fault-bounded blocks. Horsts are elongated, uplifted blocks of crust bounded by faults. S.10d S.11a 5
Fault-Block Mountains Fault-Block Mountains S.11b S.11c D. Volcanic Mountains Mountains that are formed primarily by eruptions and lava flows. See Chapter 14 notes for details. S.11d Mountain Formation Mountain Building at Convergent Boundaries Most mountain building occurs at convergent plate boundaries. Colliding plates provide the compressional forces that fold, fault, and metamorphose the thick layers of sediments deposited at the edges of landmasses. S.12 6
Mountain Formation Ocean-Ocean Convergence Mountain Building at Convergent Boundaries Ocean-Ocean Convergence mainly produces volcanic mountains. Ocean-Continent Convergence volcanic mountains and folded mountains. Continent-Continent Convergence forms folded mountains. S.13 Ocean-Continent Convergence S.15 S.14 Continent-Continent Convergence S.16 7
Mountain Formation Mountain Building at Divergent Boundaries The mountains that form along ocean ridges at divergent plate boundaries are fault-block mountains. S.17 Mountain Formation Continental Accretion Accretion is a process that occurs when crustal fragments collide with and stay connected to a continental plate. Terranes Terranes are any crustal fragments that have a geologic history distinct from that of the adjoining fragments. Terranes occur along the Pacific Coast. S.18a Continental Accretion Accretion in Western North America S.18b S.18c 8
Exercise 7 Folds and Faults! Complete Worksheet. Plate Tectonics Summary Complete the following slides. (You have 5 minutes!) S.19 Plate Tectonics Summary (1) The Earth is made up of 3 main layers (core, mantle, crust) Tectonic plates move slowly around the globe Plates are made of crust and upper mantle (lithosphere) Convection in the mantle (asthenosphere) moves the plates S.21 Plate Tectonics Summary (2) There are 2 types of plates (continental & oceanic) There are 3 types of plate boundaries (converging or subduction, diverging, sliding or transform) Volcanoes, Earthquakes and Mountain Building are closely linked to the margins of the tectonic plates S.22 9
Plate Tectonics Summary (3) There are 3 main types of volcanoes (shield, cinder, composite or stratovolcano) Volcanic activity includes rift eruptions, calderas, formation of plutons There are 2 main types of lava (felsic & mafic) Plate Tectonics Summary (4) There are 2 main types of seismic waves (surface & body) There are 2 main types of body waves (P & S) There are 4 main types of mountains (folded, fault block, dome and volcanic) S.23 S.24 UNIT TEST - Chapters 13-16 Assignments: Chapter 13 Plate Tectonics Notes & Vocab Chapter 14 Plate Tectonics & Volcanoes Notes & Vocab Chapter 15 Plate Tectonics & Earthquakes Notes & Vocab Chapter 16 Plate Tectonics & Mountain Building Notes & Vocab For Review and Test Prep: Go to esc11.weebly.com Flashcard Library (home page) volcano photo review link to practice quizzes and review PowerPoints Quizlab Chapters 13-16 Practice Test S.20 10