11.2 Types of Mountains
I. General Info
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The combined processes that create a mountain belt is called orogenesis.
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Mountains are classified by the dominant processes that have formed them.
II. Folded Mountains
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Mountains formed primarily by folding are called folded mountains.
– Compressional stress is the major force.
– Thrust faulting also plays a role.
– Ex: Appalachians, northern Rockies, & the Alps
III. Fault-Block Mountains
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Large-scale normal faults are associated with structures called fault-block mountains.
– Large blocks of crust are uplifted & tilted along normal faults
– Tensional stress produces blocks of stretched crust called grabens that drop down into elongated
valleys bordered by relatively uplifted structures called horsts.
– Ex: Teton Range of Wyoming and Sierra Nevada of California
IV. Domes & Basins
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When upwarping produces a circular or elongated structure, the feature is called a dome.
– Rocks get younger from the center out.
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Downwarped structures having a circular shape are called basins.
– Thought to be result of large accumulations of sediment compacting the crust.
– Rocks get older from the center out.