The Solid Earth - Chapter 8: Mountain Types Flashcards
Give the four main categories of mountains.
- folded/complex
- volcanic
- fault-block
- upwarped
True or false: there are structures like plateaus that have the topographical expression of mountains, but they lack the structure associated with orogenesis
True
Most orogenesis occurs in ____ environments
compressional
What is evidence that most orogenesis occurs in compressional environments?
the predominance of large thrust faults and folded strata in mountainous area
The mountains that form under tensional stresses are called _______ and are bounded on at least one side by high to moderate angle-normal faults
fault block mountains
Some fault-block mountains form in response to broad uplifting which causes _____ and faulting
elongation
What do some scientists propose as an alternative to the explanation of uplifting?
It was triggered when horizontal oceanic slab was thrust under continent and began to sink. Sinking of the ocean slab allowed the upwelling of hot material from the asthenosphere. This upwarping was a result and caused tension fracturing in the crust.
This type of mountains is produced in association with a broad arching of the crust, or, in some instances, because of vertical displacement along high angle faults
upwarped mountains
Why are the Black Hills in western South Dakota consisting of older igneous and metamorphic bedrock?
Because this was once mantled with sediment, and as the regions were upwarped, erosion removed the veneer of sedimentary strata, leaving behind a core of igneous and metamorphic rocks
The largest and most complex mountain systems are ____
folded or complex
Although folding is often more conspicuous, ____, ___, and ____ activity are always present in varying degrees
igneous activity
metamorphism
faulting
