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 FAULTSIn 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 FAULTSCan produce steps in the landscape.Steps are called FAULT SCARPS.

FOLDS, FAULTS & MOUNTAIN BELTS

TYPES OF FAULTS

NORMAL DIP-SLIP FAULTSTension 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 FAULTSHanging 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 FAULTSA 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

AlpsSedimentation and

Continental Collision

Catskill Mtns., NYEroded Peaks

Mauna Loa, HIBasaltic Outflowing

FOLDS, FAULTS & MOUNTAIN BELTS

BUILDING MOUNTAINS

Mountains are being continuously created.Some are young -- Himalaya and AndesSome are old -- AppalachiansSome 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 BELTSBUILDING MOUNTAINS

CONTINENTAL SHIELD (Canadian Shield)

FOLDS, FAULTS & MOUNTAIN BELTS

OROGENESIS (Mountain Building)

Two main mechanisms1. Volcanism

FOLDS, FAULTS & MOUNTAIN BELTS

OROGENESIS (Mountain Building)

2. Deformation and UpliftA. 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 UpliftFold and Thrust Mountains

FOLDS, FAULTS & MOUNTAIN BELTS

OROGENESIS (Mountain Building)

2. Deformation and UpliftB. 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 UpliftC. 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 MountainsAdirondack Mountains, NY

EARTHQUAKES

EARTHQUAKE

A sudden release of energy accumulated in deformedrocks 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 adjacentfault blocks prevents further movement.

Stress resumes and builds up again.Friction between the blocks is overcome.Another earthquake occurs.

EARTHQUAKES

FOCUS orHYPOCENTER --Precise undergroundspot at which rocksbegin to break or move.

EPICENTER --The point on the Earth’ssurface directly above the focus.

EARTHQUAKES

AFTERSHOCKS are continued shaking of the Earthafter an earthquake that results from the rockstrying 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.