Kobe, Japan

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS DIP-SLIP FAULTS Exhibit vertical movement. Fault blocks move up or down relative to each other.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS DIP-SLIP FAULTS

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS NORMAL DIP-SLIP FAULTS In a NORMAL DIP-SLIP FAULT the hanging wall moves down relative to the foot wall. Produced by tensional stresses. Found at divergent plate boundaries. Mid-oceanic divergence zone is >60,000 km long.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS NORMAL DIP-SLIP FAULTS Can produce steps in the landscape. Steps are called FAULT SCARPS.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS NORMAL DIP-SLIP FAULTS Tension can produce sequences of normal faults. Results in production of HORSTS and GRABENS. Such is the East African Rift Valley and Connecticut River Valley.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS HORSTS AND GRABENS

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS REVERSE DIP-SLIP FAULTS Hanging wall moves up relative to the foot wall. Produced by compressional forces. Found at convergence zones. Carries older rocks up over younger rocks.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS REVERSE DIP-SLIP FAULTS A low-angle reverse fault (<45  ) is called a THRUST FAULT. A very low angle reverse fault (<10  ) is called an OVERTHRUST. Large slabs of rock can move horizontally over large distances.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS REVERSE DIP-SLIP FAULTS OVERTHRUST FAULT. Going to the Sun Mtn. Glacier National Park, MT

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS MOUNTAIN Part of the Earth’s crust that stands > 300 m (1000’) above the surrounding landscape. Has a discernable top or summit. Possesses sloping sides.

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS Every continent has mountains. Every ocean basin has mountains.

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS Some mountains are isolated peaks. Some mountains occur in ranges or systems.

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS Form in a variety of ways Alps Sedimentation and Continental Collision Catskill Mtns., NY Eroded Peaks Mauna Loa, HI Basaltic Outflowing

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS Mountains are being continuously created. Some are young -- Himalaya and Andes Some are old -- Appalachians Some are really old -- CONTINENTAL SHIELD Shield areas generally are so old that they have been eroded flat. Local example includes the Canadian Shield. Forms the core of North America.

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS CONTINENTAL SHIELD (Canadian Shield) Composed of highly deformed and metamorphosed rocks. Shield rocks are eroded flat.

FOLDS, FAULTS & MOUNTAIN BELTS BUILDING MOUNTAINS CONTINENTAL SHIELD (Canadian Shield)

FOLDS, FAULTS & MOUNTAIN BELTS OROGENESIS (Mountain Building) Two main mechanisms 1. Volcanism

FOLDS, FAULTS & MOUNTAIN BELTS OROGENESIS (Mountain Building) 2. Deformation and Uplift A. Fold and Thrust Mountains Produced by plate collisions. Results in high mountain systems. Usually marine sediments that become highly folded and metamorphosed. Commonly have igneous intrusions. Examples include the Alps, the Himalaya, the Urals and the Canadian Rockies.

FOLDS, FAULTS & MOUNTAIN BELTS OROGENESIS (Mountain Building) 2. Deformation and Uplift Fold and Thrust Mountains

FOLDS, FAULTS & MOUNTAIN BELTS OROGENESIS (Mountain Building) 2. Deformation and Uplift B. Fault Block Mountains Bounded by high angle normal faults. Produced by tensional forces. Horsts and grabens common. Examples include the Great Basin of the western United States.

FOLDS, FAULTS & MOUNTAIN BELTS TYPES OF FAULTS HORSTS AND GRABENS

FOLDS, FAULTS & MOUNTAIN BELTS OROGENESIS (Mountain Building) 2. Deformation and Uplift C. Upwarped Mountains Large area of continent is domed up. Very little deformation of rocks. Located far from plate boundaries. Not exactly sure how they form. Example: Adirondack Mountains, NY

FOLDS, FAULTS & MOUNTAIN BELTS OROGENESIS (Mountain Building) C. Upwarped Mountains Adirondack Mountains, NY

EARTHQUAKES EARTHQUAKE A sudden release of energy accumulated in deformed rocks causing the ground to tremble or shake. Causes rupturing or brittle failure of crustal rocks. Energy is released. Movement of fault blocks takes place along a fault plane.

EARTHQUAKES After energy is released, friction between the adjacent fault blocks prevents further movement. Stress resumes and builds up again. Friction between the blocks is overcome. Another earthquake occurs.

EARTHQUAKES FOCUS or HYPOCENTER -- Precise underground spot at which rocks begin to break or move. EPICENTER -- The point on the Earth’s surface directly above the focus.

EARTHQUAKES AFTERSHOCKS are continued shaking of the Earth after an earthquake that results from the rocks trying to find a new equilibrium in new positions.

EARTHQUAKES SEISMIC WAVES When rocks break in an earthquake, energy is released. The energy released has high velocity and moves rapidly though the adjacent rocks. Energy is transmitted via SEISMIC WAVES. These waves are generally low frequency sound waves. Generally they are so low that we can’t hear them.