ch 14 mountains

What is the difference between terrane and terrain?

"Terrane" describes a crustal fragment consisting of a distinct and recognizable series of rock formations that has been transported by plate tectonic processes, whereas "terrain" describes the shape of the surface topography.

A divergent boundary will be characterized by what feature?

A rift zone

The Atlantic Coastal Plain is underlain by a portion of which continent?

Africa

The largest of the shields is the ________ shield.

African

What is an accretionary wedge, and how does it form?

An accretionary wedge is an accumulation of deformed, thrust-faulted sediments and scraps of ocean crust. This wedge is plastered against the edge of the overriding plate from the subducting plate.

Which U.S. region is made up of a series of high-angle normal faults producing nearly parallel mountain ranges?

Basin and Range Province

________ contain large quantities of preexisting sedimentary and crystalline rocks that have been faulted and contorted into a series of folds.

Compressional mountains

According to the plate tectonics model, most global mountain ranges are associated with which kind of plate boundary?

Convergent

Why would geologic mapping be difficult in an area dominated by accreted terranes?

Each terrane is geologically distinct, but also highly deformed

T/F: Because North America continues to collide with the Eurasian plate, the Appalachians are still actively forming.

False

How does formation of fault-block mountains differ from the processes that generate most other major mountain belts?

Fault-block mountains form by the lithosphere rising because of hot mantle rock upwelling below that area, whereas most other mountains form by the convergence of two lithospheric plates.

Which mountain range consists of the youngest collisional mountains on Earth?

Himalayas

What is isostasy, and what does it indicate about a floating object that has a weight added or removed?

Isostasy is the concept that Earth's crust is floating within the mantle in gravitational balance. Thus, if weight is added, the crust would sink until it reached a new isostatic balance. Conversely, if weight is removed from the crust, it would rise until it reached a new isostatic balance.

Which orogeny is largely responsible for creating the modern Rocky Mountains?

Laramide Orogeny

Which type of volcanic material will dominate the eruptions along a continental volcanic arc?

Lavas of intermediate or felsic composition

What causes mountain formation in a continental rifting setting?

Lithospheric blocks, bounded by normal faults, tilt and rise.

What are fault-block mountains?

Mountains formed through crustal extension and normal faulting

How do mountainous regions experience gravitational collapse?

Mountains that have risen to extreme heights experience ductile spreading at depth and normal faulting as well as subsidence in the upper, brittle portion of Earth's crust.

Which best describes the unique and varied bedrock geologic history of the northwest coast of North America?

Multiple terranes accreted onto the continental crust.

Notice the part of this image labeled "continued trench rollback." What is happening in "trench rollback"?

Old, dense lithosphere sinks, creating slab suction that pulls the upper plate toward the trench.

Which of the following statements best characterizes the geology and structure of the Appalachian Mountains?

Sedimentary strata folded at in the late Paleozoic Era

What is an accretionary wedge?

Sediments and ocean crust fragments being scraped off of a subducting plate

Which of the following is believed to be responsible for uplifting southern Africa 1,500 meters higher than what would be expected for a stable continental platform?

Superplume

Which factor(s) will most influence the depth of deep-ocean trenches?

Temperature and density of the plate

How do back-arc basins form?

Tensional stresses resulting from slab suction stretch this part of the crust, causing it to thin vertically.

A ________ is a crustal fragment that has been transported by plate tectonics and has adhered to an overriding plate.

Terrane

In what ways are the Sierra Nevada and the Andes ranges similar?

The Sierra Nevada range exhibits evidence of Andean-type mountain building with the range's placement along an active continental margin, the Sierra Nevada Batholith that is a remnant of a continental volcanic arc, and the Coast ranges that represent either an accretionary wedge or a past island arc offshore. Submit

A mountain range with peaks as high as 14,000 feet above sea level has formed. As time passes, erosion wears down the mountains. How will isostacy affect the crust?

The mountain range will rise

Why is the Hudson Bay region slowly uplifting?

The region is experiencing isostatic uplift after being covered by thick glaciers.

What is a suture?

The zone where two continents are welded together Submit

The Cascadia subduction zone off the coast of Washington and Oregon famously lacks a well-defined deep-ocean trench. Why might this be the case?

There is a shallow angle of plate subduction, as well as large quantities of sediment infill.

As India is colliding with Asia, the margin of Asia is experiencing significant deformation. What is happening to the rocks that are being deformed?

They are being displaced to the southeast to make up Southeast Asia Submit

Which of the following best explains why some fault-block mountains have an elevated topography?

Thinning of the lithosphere resulted in upwelling of hot mantle rock and greater lithospheric buoyancy

T/F: While lithosphere is being created at the mid-ocean ridge, it is also being destroyed at the subduction zone, thus Earth remains the same size.

True

What composition of magma is initially generated in a subduction zone?

basaltic

Fold-and-thrust belts are the result of ________ stress whereas fault-block mountains are the result of ________ stress.

compressional; tensional

In oceanic-continental convergence, a volcanic arc is created on the ________ and is the result of ________ rising up from a subducting plate.

continental plate; magma

Which type of plate boundaries is most directly associated with Earth's major mountain belts?

convergent boundary

A ________ will form as sediment collects between the accretionary wedge and the volcanic arc.

forearc basin

Part A: Rank the density of the lithosphere at points A, B, and C.

highest -> lowest A; C; B

Which type of subduction would result in tensional forces at a subduction zone?

subduction of an old, dense plate

What kind of stress would be affecting the marked region in this image?

tension

What is orogenesis?

the collection of processes that produce a mountain belt

What are the four major features of a subduction zone?

volcanic arc, deep-ocean trench, forearc, back-arc