Chapter-11 Mountain Building Notes

Section 11.1 “Where Mountains Form” 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

Section 11.1 “Where Mountains Form” 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

Compare and contrast Active and Passive Continental Margins: 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

Objective – 4: Compare and Contrast Anticlines and Synclines

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.

A strike-slip fault moves horizontally along a fault line. 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

Fault-block Mountains 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. Type of Crust Where are they found Uplift Mechanism Examples of Plutonic Dome Mountain: Crustal and igneous rock inland Isolated structures in flat lying sedimentary rocks Igneous intrusion Border of the Colorado Rockies Tectonic Dome Mountain Crustal rock inland Uplift force Adirondack Mtns. Folded Mountain Continental Crust Continental – continental plate boundaries Continued plate movement Alps, Appalachians Volcanic Mountain Continental, near Subduction boundary Subduction boundary Volcanic material (magma, ash, etc.) Cascades Fault-block Mountain Continental Western US Uplift forces Sierra Nevada Mountains

Mountains End