Transcript
WHAT IS OROGENY?Processes of mtn building
DeformationFolding and thrust-faulting
Metamorphism
Intrusions: batholiths, etc
Volcanic Activity
TYPES OF MOUNTAINS
• Volcanic: Shield and composite
• Fault-block: normal faulting and tension
• Folded: reverse faults and compression
• Complex: mixture of most of the above
Mauna Kea
Shield volcanoHot SpotBasalt
Mauna Loa inBackground
Kilaeua is Behind MaunaLoa
KilaeuaNewest ground inThe world
Asthenosphere comingTo the surface
Composite VolcanoMt Rainier
Compressive forcesSubduction zonesAndesitic composition
Guagua Pichincha, EcuadorQuito in foregroundComposite volcanoes explosive
Normal fault
Footwall moves Up relative toHanging wall
Tension forces
FOOTWALL
HANGING WALL
Tilted fault-block range: Sierra Nevada from east,Steep side of block fault; Ansel Adams photo
Tilted Fault-blockSierra Nevada from westSide, low angle
Yosemite valley the result Of glaciation on low-anglerelief
Wasatch RangeFrom Salt Lake City
Typically fault-Block system
Grand Tetons: Another fault-block system
Alternating normal faults lead to a characteristic pattern called aHorst and Graben system. An area under tension will often haveMultiple mountain ranges as a result.
Basin and range province: tilted fault-block mountains in Nevada.The results of a horst and graben system. Nevada is under tension Because of rising magma which is unzipping the system, all the wayFrom Baja California
Sierra Nevada and Wasatch Ranges part of this system
REVERSE FAULTS: Hanging wall moves up relative to footwallResult of compression: plates collidingTwo types: low-angle or thrust faults, and high-angle reverse faults
Individual layers can move 100’s of kilometersAlps are a great example
Thrust faults main cause Of folded mountains
Appalachian Mountains of the US
Atlas Mountains, Northern Africa
Classic folded terrain: well-developed anticline
ZAGROS MTSPERSIAN GULF
AlternatingAnticlines andSynclines
High-angle reverse faultsForms “Sawtooth Mtns”
Flatirons classic example
Sawtooth effect result ofDifferential erosion
White Cloud peak
SAWTOOTH RANGE,IDAHO
Alice Lake
COMPLEX MOUNTAINS
Tend to have a little ofEverything: volcanoes,Folds, thrust faults, normalfaults
ALPS
HIMALAYAS
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