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Learn how major mountain belts form along plate boundaries through processes like subduction and compression. Explore the different types of stress that deform rocks and create mountains.
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Objective – 1: Explain how some of earth’s major mountain belts formed. • Section 11.1 “Where Mountains Form” • Mountain – A large mass of rock that rises a great distance above its base • Mountain Belts: • Mountain ranges that follow convergent plate boundaries • NA Cordillera – mountain belt that runs down the western side of NA from Alaska to Mexico • Appalachian Mountains do not lie along a plate boundary
Objective – 1: Explain how some of earth’s major mountain belts formed. • Section 11.1 “Where Mountains Form” • Some mountain belts are formed along active continental margins by the subducted plate pushing up the overriding plate • Therefore most mountain ranges are located along plate boundaries
Objective – 2: Compare and contrast active and passive continental margins. • Define: • Continental margin: is a boundary between continental crust and oceanic crust • Passive continental margin: stable areas that are not located near plate boundaries
Objective – 2: Compare and contrast active and passive continental margins. • Compare and contrast Active and Passive Continental Margins: • Active – located along plate boundaries; both lie along continental margins; • Passive – Not located along any plate boundaries; consists of mainly marine sediments; weathered rock;
Objective – 2: Compare and contrast active and passive continental margins. • Looking at the Plate Boundary Map on pages 712 – 713, there are a number of Active and Passive continental margins: • Active continental margins include west coast of South America; west coast of North America; east coast of Japan; west coast of Indonesia; • Passive continental margins include east coast of N America; east coast of S America; west coast of Africa; south east coast of Africa; etc.
Active continental margins: Passive margins: Active continental margins are along continental/ocean boundaries located at plate boundaries.
Chapter 11 Section 2 How Mountains Form:
Objective – 3: Explain how compression, tension, and shear stress deform rocks. • Types of Stress: • Forces involved in plate interactions produce features such as folds and faults. • Folded Mountains: • Two plates collide, can cause folding of rock • Before two continents can collide the ocean basin between them must close: Subduction • Himalayas formed by the ocean basin between India and Tibet closed due to Subduction.
Objective – 3: Explain how compression, tension, and shear stress deform rocks. • Dome Mountains: • Nearly circular folded mountain • Individual isolated structures • Plutonic dome Mountain: • Formed by overlaying crustal rock pushed up by an igneous intrusion such as a laccolith. • Center rocks (igneous) are younger than the outer rocks • Tectonic Dome Mountains: • Result of uplifting forces that arch rock layers upward • All the rocks were present before the uplift occurred
Objective – 3: Explain how compression, tension, and shear stress deform rocks. • Fault-block Mountains • The crust is stretched (tensional forces) and normal faults are created • Whole blocks are pushed up • Horst and Grabens • Tensional stress and normal faulting cause these • Between tensional faulting, grabens (large blocks) have dropped • When large blocks are thrust upward, between normal faults, it is called a Horst
Objective – 3: Explain how compression, tension, and shear stress deform rocks. • Define: • Anticline – an up-fold in rock layers • Syncline – down-fold in rock layers • Stress Types: • Compression – rock layers are being squeezed together • Tension – rock layers are being stretched or pulled apart • Shear – rock layers are being pushed in two different, opposite directions.
Objective – 3: Explain how compression, tension, and shear stress deform rocks.
Objective – 3: Explain how compression, tension, and shear stress deform rocks. • Draw a sketch of a compression, tension and shear stress:
Objective – 4: Compare and Contrast Anticlines and Synclines • An anticline is an up-fold of the rock layers • A Syncline is a is a down-fold of the rock layers • Both are usually caused by compressional forces
Objective – 4: Compare and Contrast Anticlines and Synclines Syncline
Objective – 4: Compare and Contrast Anticlines and Synclines Anticline
Objective – 5: Distinguish among the three major types of faults – normal, reverse, and strike-slip.
Objective – 5: Distinguish among the three major types of faults – normal, reverse, and strike-slip.
Objective – 5: Distinguish among the three major types of faults – normal, reverse, and strike-slip.
Objective – 5: Distinguish among the three major types of faults – normal, reverse, and strike-slip. • The difference between a normal fault and a reverse fault are the stresses that cause them: • Reverse fault is caused by compressional forces • Normal fault is caused by tensional forces • A strike-slip fault moves horizontally along a fault line.
Chapter 11 Section 3 Types of Mountains
Objective – 6: Classify mountain ranges by their most prominent features. • Folded Mountains: • Two plates collide, can cause folding of rock through compressional stress • Before two continents can collide the ocean basin between them must close: Subduction • Himalayas formed by the ocean basin between India and Tibet closed due to Subduction.
Objective – 6: Classify mountain ranges by their most prominent features. • Dome Mountains: • Nearly circular folded mountain • Individual isolated structures • Plutonic dome Mountain: • Formed by overlaying crustal rock pushed up by an igneous intrusion such as a laccolith. • Center rocks (igneous) are younger than the outer rocks • Tectonic Dome Mountains: • Result of uplifting forces that arch rock layers upward • All the rocks were present before the uplift occurred
Objective – 6: Classify mountain ranges by their most prominent features. • Fault-block Mountains • The crust is stretched (tensional forces) and normal faults are created • Whole blocks are pushed up
Objective – 6: Classify mountain ranges by their most prominent features. • Horst and Grabens • Tensional stress and normal faulting cause these • Between tensional faulting, Grabens (large blocks) have dropped • When large blocks are thrust upward, between normal faults, it is called a Horst
Objective – 6: Classify mountain ranges by their most prominent features. • When two land masses collide, they usually crumple and form folded mountains. • Volcanic mountains tend to form on the overriding plate at a Subduction zone. • Fault Block Mountains form when the earth’s crust is slowly up-lifted. • The uplift has caused the crust to stretch and crack, forming normal faults along the surface. As uplift continues, whole blocks of crust have been pushed up.
Objective – 7: Compare and contrast folded mountains, dome mountains, volcanic mountains, and fault-block mountains.
Mountains End