Deck 31: Plate Movement: Causes and Effects

Question 1

The process of upwelling magma at divergent boundaries with subsequent movement away from those boundaries, and the return flow of cooled rock to deep in the mantle form cycles of slowly moving rock may be explained by:

A) the rock cycle
B) convection currents
C) volcanic activity
D) earthquakes

Answer 1

B

Question 2

The higher the mountain, the deeper its root.

Answer 2

True

Question 3

When George Everest took his gravity measurements by dropping a plumb line along the flank of a mountain range, he expected the mountain to attract the plumb line from vertical toward the range due to density differences. Instead, calculations later done by John Pratt showed that the plumb line experienced far less attraction toward the mountain than expected. It was concluded that:

A) The mantle rocks below the mountain range were not as dense as expected.
B) Mountain ranges are very large, dense structures.
C) The rocks under the mountain range have far less density beyond its base than its surrounding rocks.
D) He needed to attach a heavier weight onto his plumb line when suspending it next to a mountain range for it to experience greater attraction.

Answer 3

C

Question 4

The theory that describes the depression and rebound of continental crust due to adding or removing weight is called:

A) continental drift
B) seafloor spreading
C) plate tectonics
D) isostasy

Question 5

Isostasy, the condition of equilibrium between floating landmasses and the denser rock beneath them, can best be explained by:

A) greater crustal thickness extending below sea level
B) a high density root system caused less dense landmass to float
C) a low density root system caused parts of the crust to stand much higher
D) both (a) and (c)

Question 6

What processes explain the thickening of the lithosphere?

A) collision of lithospheric plates
B) subduction of oceanic crust beneath continental crust
C) as time progresses, sediments build up making the lithosphere thicker
D) all of the above
E) both (a) and (b) only

Question 7

The collision of the Indian and Eurasian Plates has led to intense compression and lifting of the Himalayan peaks and the Tibetan Plateau.

Question 8

The following statement provides the best possible explanation as to why many high mountain ranges are found at some distance from plate boundaries, such as the Rocky Mountains of the western United States and Canada that are found some distance away from the San Andreas fault.

A) Uplift is related to stress transmitted from distant collision zones
B) Yet to be discovered plate boundaries actually exist under these mountain ranges
C) Mantle plumes from deep beneath the surface push landmasses upward
D) None of the above. Mountains do not form away from plate boundaries.

Question 9

As mountain ranges, such as the Appalachian Mountains, erode, the:

A) mountain peaks are standing at a lower elevation and will eventually disappear completely
B) mountain peaks are slowly disappearing into a flat land
C) mountain peaks are standing at or near their original elevation
D) mountains will eventually disappear and then grow into a large mountain belt again

Question 10

After studying a region in the Northwestern part of the United States, observations and laboratory studies show that a mountain belt juxtaposed to a low-lying area are compositionally and structurally different and hundreds of thousands of years apart in age from each other. Which statement best explains this anomaly?

A) Foreign mountain ranges are accreted onto continental shields bringing unrelated rock types next to each other
B) Having a mountain belt that is compositionally and structurally unrelated to its neighboring low land is not possible
C) Mountain belts are different from the surrounding low-lying areas by the down drop of continental rock under lower mantle rock
D) both (a) and (c)