WHAT IS OROGENY? Processes of mtn building Distinctive patterns of deposition eugeocline, miogeocline Deformation Folding 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 volcano Hot Spot Basalt Mauna Loa in Background Kilaeua is Behind Mauna Loa

Kilaeua Newest ground in The world Asthenosphere coming To the surface

Composite Volcano Mt Rainier Compressive forces Subduction zones Andesitic composition

Guagua Pichincha, Ecuador Quito in foreground Composite volcanoes explosive

Normal fault Footwall moves Up relative to Hanging wall Tension forces FOOTWALL HANGING WALL

Tilted fault-block range: Sierra Nevada from east, Steep side of block fault; Ansel Adams photo

Tilted Fault-block Sierra Nevada from west Side, low angle Yosemite valley the result Of glaciation on low-angle relief

Wasatch Range From Salt Lake City Typically fault- Block system

Grand Tetons: Another fault-block system

Alternating normal faults lead to a characteristic pattern called a Horst and Graben system. An area under tension will often have Multiple 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 way From Baja California Sierra Nevada and Wasatch Ranges part of this system

REVERSE FAULTS: Hanging wall moves up relative to footwall Result of compression: plates colliding Two types: low-angle or thrust faults, and high-angle reverse faults Individual layers can move 100’s of kilometers Alps 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 MTS PERSIAN GULF Alternating Anticlines and Synclines

High-angle reverse faults Forms “Sawtooth Mtns” Flatirons classic example Sawtooth effect result of Differential erosion

White Cloud peak SAWTOOTH RANGE, IDAHO Alice Lake

COMPLEX MOUNTAINS Tend to have a little of Everything: volcanoes, Folds, thrust faults, normal faults ALPS HIMALAYAS